Artykuły w czasopismach: „Co3O4 Morphology”

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Zhang, Ruili, Yuntao Yang i Ping Yang. "Three-Dimensional Precursor-Derived Synthesis of Co3O4 Towards High Electrochemical Performance". Nanoscience and Nanotechnology Letters 11, nr 10 (1.10.2019): 1375–86. http://dx.doi.org/10.1166/nnl.2019.3024.

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Three-dimensional (3D) cobalt oxide (Co3O4) flowers with different shapes were prepared by a facile hydrothermal synthesis. The morphology of Co3O4 precursors has adjusted obviously from acicular shapes to acicular-sheet-like flowers and then to sheet-like flowers by changing reaction temperature and solution concentration. After annealing, as-prepared precursors were converted into 3D flower-like Co3O4 samples and their morphology and sizes were well preserved. The effect of experimental conditions on growth of Co3O4 precursors was explored and the growth mechanism was proposed. Moreover, the electrochemical properties of various Co3O4 with different shapes were tested. The result of electrochemical investigation indicates that 3D flower-like Co3O4 assembled by sheets exhibited high capacitance and excellent cycling performance.

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Tan, Hui Yun, i Zhao Yu Ren. "Facile Synthesis of Co₃O₄/Nitrogen-Doped Graphene Composite with Enhanced Electrochemical Performance". Materials Science Forum 847 (marzec 2016): 14–21. http://dx.doi.org/10.4028/www.scientific.net/msf.847.14.

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Co3O4 nanoflakes/N-doped graphene (NG) was synthesized through a facile two-step synthesis route. The phase composition and morphology of the products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS). It has been found that introduction of NG has effects on the morphology of Co3O4 and leads to a well distribution of Co3O4 nanoflakes. The electrochemical properties of as-synthesized materials were measured by cyclic voltammetry (CV), galvanostatic charge/discharge tests and electrochemical impedance spectroscopy (EIS). The composite presents an enhanced supercapacitor performance than the pristine Co3O4 nanoflakes, mainly due to the strong synergistic effect of the NG and Co3O4.

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Li, Zhengsheng, Ruitang Guo, Zhidong Lin, Xiangyin Ji, Ye Yuan, Longfei Hong i Weiguo Pan. "Facile synthesis of Co₃O₄ nanoparticles with different morphology for efficient water oxidation in alkaline media". Journal of Physics: Conference Series 2263, nr 1 (1.04.2022): 012013. http://dx.doi.org/10.1088/1742-6596/2263/1/012013.

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Abstract Hydrogen production from water electrolysis is an important measure to achieve clean and sustainable energy in the future. Oxygen evolution reaction is a half-reaction of water electrolysis process, and its efficiency has a great influence on the overall reaction. The morphology of the catalyst has a great influence on the catalytic performance of the catalyst for oxygen evolution, but the mechanism of the effect of the morphology on the activity is still unclear. Therefore, the influence of the catalyst morphology on the catalytic activity needs to be studied urgently. Co3O4 is widely used in oxygen evolution reactions. Therefore, we took three Co3O4 with different morphologies as the research objects to study the effect of morphology on the oxygen evolution activity of Co3O4. The results show that among the three different morphologies of cobalt tetroxide, the Co3O4 with porous sheet morphology exhibits the best oxygen evolution activity (η10 = 1.54 V in 1 M KOH). The reason for the better activity of cobalt tetroxide with the morphology of the hollow sheet may be due to its larger specific surface area and more active sites, which reduces the reaction electron transfer barrier. Our work sheds new light on the design of novel oxygen evolution electrocatalysts.

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Kong, Linglong, Lu Wang, Deye Sun, Su Meng, Dandan Xu, Zaixin He, Xiaoying Dong, Yongfeng Li i Yongcheng Jin. "Aggregation-Morphology-Dependent Electrochemical Performance of Co3O4 Anode Materials for Lithium-Ion Batteries". Molecules 24, nr 17 (29.08.2019): 3149. http://dx.doi.org/10.3390/molecules24173149.

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The aggregation morphology of anode materials plays a vital role in achieving high performance lithium-ion batteries. Herein, Co3O4 anode materials with different aggregation morphologies were successfully prepared by modulating the morphology of precursors with different cobalt sources by the mild coprecipitation method. The fabricated Co3O4 can be flower-like, spherical, irregular, and urchin-like. Detailed investigation on the electrochemical performance demonstrated that flower-like Co3O4 consisting of nanorods exhibited superior performance. The reversible capacity maintained 910.7 mAh·g−1 at 500 mA·g−1 and 717 mAh·g−1 at 1000 mA·g−1 after 500 cycles. The cyclic stability was greatly enhanced, with a capacity retention rate of 92.7% at 500 mA·g−1 and 78.27% at 1000 mA·g−1 after 500 cycles. Electrochemical performance in long-term storage and high temperature conditions was still excellent. The unique aggregation morphology of flower-like Co3O4 yielded a reduction of charge-transfer resistance and stabilization of electrode structure compared with other aggregation morphologies.

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Zia, Adeel, Abdul Basit Naveed, Aftab Javaid, Muhammad Fahad Ehsan i Azhar Mahmood. "Facile Synthesis of ZnSe/Co3O4 Heterostructure Nanocomposites for the Photocatalytic Degradation of Congo Red Dye". Catalysts 12, nr 10 (7.10.2022): 1184. http://dx.doi.org/10.3390/catal12101184.

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In the present paper, simple hydrothermal and solid-state methods are reported for the synthesis of metal chalcogenide (ZnSe), metal oxide (Co3O4) and their nano-heterostructure (ZnSe/Co3O4 3:1, 1:1 and 1:3 ratios by weight), while their photocatalytic efficiencies are also investigated. The X-ray diffraction results corroborate the good crystallinity and purity of all synthesized products, i.e., ZnSe, Co3O4 and their nanocomposites. The scanning electron micro-images of ZnSe show a mixed morphology of nanoparticles (≈16 nm), including spherical and distorted cubes, while Co3O4 has a worm-like morphology (≈20 × 50 nm). The EDX results show that all the elements are present in accordance with their anticipated amounts in the products. The UV/visible absorption spectrum of ZnSe depicts a sharp absorption at around 480 nm, while Co3O4 demonstrates two prominent peaks, 510 nm and 684 nm. The prepared samples were employed for the photocatalytic degradation of Congo red dye and the nano-heterostructure (ZnSe/Co3O4 3:1) shows an exceptional photocatalytic degradation efficiency of 96%. This enhanced photocatalytic activity was due to the synergic effect of ZnSe and Co3O4 that reduced the electron/hole recombination and caused suitable bandgap alignment.

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Yulizar, Yoki, Dewangga Oky Bagus Apriandanu i Yessi Pratiwi. "Formation of Co₃O₄ Nanoparticles Using Moringa oleifera Leaves Extract through Two Phases System of Hexane-Water and their Photocatalytic Activity". Materials Science Forum 982 (marzec 2020): 9–13. http://dx.doi.org/10.4028/www.scientific.net/msf.982.9.

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Co3O4 nanoparticles (NP) have been successfully formed using Moringa oleifera leaves extract (MLE) through two phases’s system of hexane–water. Co3O4 NP was further characterized using UV-Vis DRS, FT-IR, TEM, SEM-EDX, XRD and UV-Vis spectrophotometer. FTIR spectra of Co3O4 NP had strong absorption bands at wavenumbers of 538 and 670 cm-1. The bandgap energy value of Co3O4 NP was 1.43 eV. In addition, the characterization of SEM and TEM showed that the morphology of Co3O4 NP was in the spheres form with particle sizes around 73 nm. The photocatalytic activity of Co3O4 NP was carried out for methylene blue (MB) photodegradation. Co3O4 NP had photodegradation activity against MB under visible light irradiation of 91% for 120 min.

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Wang, Chao, Wenchao Hua, Guangtao Chai, Chuanhui Zhang i Yanglong Guo. "Insights into the Morphological Effect of Co3O4 Crystallite on Catalytic Oxidation of Vinyl Chloride". Catalysts 9, nr 5 (30.04.2019): 408. http://dx.doi.org/10.3390/catal9050408.

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Co3O4 catalysts of cube and sphere shapes were prepared by one-step hydrothermal synthesis with different controlled amounts of Co(NO3)2·6H2O and NaOH. The morphological effects on both physicochemical properties and catalytic activities of vinyl chloride oxidation were investigated by material characterization and performance evaluation. The obtained results showed that the morphology, resulting in the exposure difference of crystal planes, significantly affected the catalytic property. The catalytic activity for vinyl chloride oxidation followed a descending order of Co3O4 cube (Co3O4-c) > Co3O4 sphere (Co3O4-s) > Co3O4 commercial (Co3O4-com). The cube-shaped Co3O4 presented higher catalytic activity and stability than Co3O4 spheres despite their similar crystallographic structures as well as physicochemical and redox properties. Accordingly, the different catalytic behaviors should be attributed to a morphological effect. The Co3O4 cube with a preferential exposure of (001) plane presented higher abundance of surface Co2+ cations and adsorbed oxygen species, which acted as the active sites responsible for the improvement of its catalytic activity.

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Абдуллин, Х. А., С. К. Жумагулов, Г. А. Исмаилова, Ж. К. Калкозова, В. В. Кудряшов i А. С. Серикканов. "Синтез гетерогенных наноструктур ZnO/Co-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=- методом химического осаждения из растворов". Журнал технической физики 90, nr 7 (2020): 1184. http://dx.doi.org/10.21883/jtf.2020.07.49454.317-19.

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Nanocrystalline cobalt oxide Co3O4 and the ZnO / Co3O4 composite were obtained by the chemical bath deposition method followed by thermal annealing. It has been shown that the growth mechanism of cobalt carbonates changes dramatically in the presence of zinc oxide particles during synthesis, as a result, the phase composition, morphology, and material properties change. The conductive layers formed from the ZnO / Co3O4 composite have an electrical resistance at room temperature that is more than three orders of magnitude lower than the resistance of the Co3O4 layers, and ZnO / Co3O4 composite gas sensors showed significantly higher gas sensitivity at room temperature than that of control cobalt oxide sensors.

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Wei, Xuejiao, Sami Barkaoui, Jingwen Chen, Guiping Cao, Zeying Wu, Fei Wang i Gao Li. "Investigation of Au/Co3O4 nanocomposites in glycol oxidation by tailoring Co3O4 morphology". Nanoscale Advances 3, nr 6 (2021): 1741–46. http://dx.doi.org/10.1039/d1na00053e.

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Kumar, Yedluri Anil, Himadri Tanaya Das, Phaneendra Reddy Guddeti, Ramesh Reddy Nallapureddy, Mohan Reddy Pallavolu, Salem Alzahmi i Ihab M. Obaidat. "Self-Supported Co3O4@Mo-Co3O4 Needle-like Nanosheet Heterostructured Architectures of Battery-Type Electrodes for High-Performance Asymmetric Supercapacitors". Nanomaterials 12, nr 14 (7.07.2022): 2330. http://dx.doi.org/10.3390/nano12142330.

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Herein, this report uses Co3O4 nanoneedles to decorate Mo-Co3O4 nanosheets over Ni foam, which were fabricated by the hydrothermal route, in order to create a supercapacitor material which is compared with its counterparts. The surface morphology of the developed material was investigated through scanning electron microscopy and the structural properties were evaluated using XRD. The charging storage activities of the electrode materials were evaluated mainly by cyclic voltammetry and galvanostatic charge-discharge investigations. In comparison to binary metal oxides, the specific capacities for the composite Co3O4@Mo-Co3O4 nanosheets and Co3O4 nano-needles were calculated to be 814, and 615 C g−1 at a current density of 1 A g−1, respectively. The electrode of the composite Co3O4@Mo-Co3O4 nanosheets displayed superior stability during 4000 cycles, with a capacity of around 90%. The asymmetric Co3O4@Mo-Co3O4//AC device achieved a maximum specific energy of 51.35 Wh Kg−1 and power density of 790 W kg−1. The Co3O4@Mo-Co3O4//AC device capacity decreased by only 12.1% after 4000 long GCD cycles, which is considerably higher than that of similar electrodes. All these results reveal that the Co3O4@Mo-Co3O4 nanocomposite is a very promising electrode material and a stabled supercapacitor.

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Gholamrezaei, Sousan, Masoud Salavati-Niasari, Hassan Hadadzadeh i Mohammad Taghi Behnamfar. "Preparation of Co3O4 Nanostructures via a Hydrothermal- Assisted Thermal Treatment Method by Using of New Precursors". High Temperature Materials and Processes 36, nr 2 (1.02.2017): 107–12. http://dx.doi.org/10.1515/htmp-2015-0158.

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AbstractCo3O4 nanostructures have been synthesized via a hydrothermal-assisted thermal treatment process. A new complex formulated as [Co(py)2(H2O)2(NO3)2] was synthesized, and then used to prepare Co3O4 nanostructures. Cubic phase of spinel Co3O4 nanostructures with particle size of about 39 nm could be produced after calcination of the Co(OH)2 materials prepared with hydrothermal method at 160 °C for 15 h. Using of inorganic precursors decreased the time and temperature of Co3O4 preparation. The effect of pH on the morphology of the product s synthesized by hydrothermal reactions was investigated. It was found that the best morphology was achieved on pH=8, where was not prepared any precipitation. In this method, we could decrease the reaction temperature in synthetic rout to fabricate Co3O4 nanostructures. Nanostructures were characterized by SEM, TEM, X-ray diffraction (XRD), UV–visible, Fourier transformed infrared (FT-IR) spectroscopy and Nuclear magnetic resonance (1H-NMR).

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Pang, Wei Qiang, Xiao Bing Shi i Yang Li. "Preparation, Characterization of Co₃O₄ Nano-Particles and its Catalytic Effect on the Combustion of Fuel Rich Propellants". Advanced Materials Research 560-561 (sierpień 2012): 284–88. http://dx.doi.org/10.4028/www.scientific.net/amr.560-561.284.

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The mono-dispersed Co3O4 nano-particles were prepared by means of solid phase synthetical method. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by laser particle size analysis, x-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The catalytic effects of nano-particles on the combustion of fuel rich propellant were investigated. The results show that the Co3O4 nano-particles prepared are uniform and with relatively wide size distribution curve. The catalytic effect of Co3O4 nano-particles on the fuel rich propellant is stronger than those of micro-sized Co3O4 particles and CuO nano-particles.

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Wang, Jian, Yan Zhao, Yucai Li i Shiwei Song. "Morphology and Structure Induced Co3O4 Nanowires High-Performance Supercapacitor Electrode Material". Journal of Nanoelectronics and Optoelectronics 16, nr 6 (1.06.2021): 1005–10. http://dx.doi.org/10.1166/jno.2021.3044.

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The electrochemical performance of the material depends heavily on the morphologies and structural characteristics of the material. Co3O4 samples show the remarkable electrochemical performance owing to the high porosity, appropriate pore size distribution and novel architecture and the effect of NH4F for morphology. Co3O4 nanowires grown on Ni foam have been synthesized through a facile hydrothermal approach, revealing large capacitance of 2178.4 mF cm−2 at the current density of 2 mA cm−2 and superior cycling stability.

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Adimule, Vinayak, Basappa C. Yallur, Sheetal R. Batakurki i Santosh S. Nandi. "Synthesis, Morphology and Enhanced Optical Properties of Novel GdxCo<sub>3</sub>O<sub>4</sub> Nanostructures". Advanced Materials Research 1173 (25.08.2022): 71–82. http://dx.doi.org/10.4028/p-3pkhf6.

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Abstract: In the present studies, gadolinium doped cobalt oxide nanostructures (1 wt. %, 5 wt. % and 10 wt. %) were synthesized by co-precipitation method. The samples were characterized by SEM (scanning electron microscopy), XRD (X-ray diffraction spectroscopy), UV-Visible spectroscopy. UV-Visible exhibited maximum absorption at 440.81 nm for Gd(10% wt)Co3O4 Band gap energy was calculated using Tauc plots and it was observed that band gap energy decreased from 7.74 eV to 2.64 eV upon increasing the doping percentage of Gd to Co3O4. The crystallinity of the Gd(10% wt) Co3O4 NS increased as compared with Gd(1% wt)Co3O4 NS. SEM morphology revealed average particle size were between 95 nm to 78 nm uniformly distributed over Co3O4 NS.

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Chang, Abdul Sattar, Aneela Tahira, Fouzia Chang, Abdul Ghaffar Solangi, Muhammad Ali Bhatti, Brigitte Vigolo, Ayman Nafady i Zafar Hussain Ibupoto. "Highly Heterogeneous Morphology of Cobalt Oxide Nanostructures for the Development of Sensitive and Selective Ascorbic Acid Non-Enzymatic Sensor". Biosensors 13, nr 1 (16.01.2023): 147. http://dx.doi.org/10.3390/bios13010147.

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The surface tailored metal oxide nanostructures for the development of non-enzymatic sensors are highly demanded, but it is a big task due to the wide range of complexities during the growth process. The presented study focused on the surface modification of the heterogeneous morphology of cobalt oxide (Co3O4) prepared by the hydrothermal method. Further surface modification was conducted with the use of sodium citrate as a reducing and surface modifying agent for the Co3O4 nanostructures through the high density of oxygenated terminal groups from the citrate ions. The citrate ions enabled a significant surface modification of the Co3O4 nanostructures, which further improved the electrochemical properties of the Co3O4 material toward the design of the non-enzymatic ascorbic acid sensor in a phosphate buffer solution of pH 7.4. The morphology and crystal arrays of the Co3O4 nanostructures were studied by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) techniques. These physical characterizations showed the highly tailored surface features of Co3O4 nanostructures and a significant impact on the crystal properties. The electrochemical activity of Co3O4 was studied by chronoamperometry, linear sweep voltammetry, and cyclic voltammetry (CV) for the detection of ascorbic acid. The linear range of the proposed sensor was measured from 0.5 mM to 6.5 mM and a low limit of detection of 0.001 mM was also estimated. The presented Co3O4 nanostructures exhibited significant surface roughness and surface area, consequently playing a vital role toward the selective, sensitive, and stable detection of ascorbic acid. The use of a low cost surface modifying agent such as sodium citrate could be of great interest for the surface roughness and high surface area of nanostructured materials for the improved electrochemical properties for the biomedical, energy storage, and conversion systems.

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Serga, Vera, Aija Krūmiņa, Mara Lubane, Gundega Heidemane i Mikhail Maiorov. "Production of Nano-Sized Co₃O₄ by Pyrolysis of Organic Extracts". Key Engineering Materials 721 (grudzień 2016): 102–7. http://dx.doi.org/10.4028/www.scientific.net/kem.721.102.

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The most promising application field of materials based on nano-sized Co3O4 is catalysis. The method of production is one of the factors, which greatly affects the catalytic activity of Co3O4 catalysts. The aim of this research is to study possibilities of a new promising extractive-pyrolytic method (EPM) for the production of Co3O4 nanopowders and silica- and ceria-supported Co3O4 nanocomposites. Solutions of cobalt hexanoate in hexanoic acid and trioctylammonium tetrachlorocobaltate in toluene preliminary produced by solvent extraction were used as precursors. The precursors’ thermal stability, phase composition, morphology and the magnetic properties of the final products of pyrolysis were studied. The performed investigations have shown that the mean size of the Co3O4 crystallites in the materials produced by the EPM varies from amorphous to 55 nm due to the production conditions.

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Shaikh, Zaffar Ahmed, Nikita Moiseev, Alexey Mikhaylov i Serhat Yüksel. "Facile Synthesis of Copper Oxide-Cobalt Oxide/Nitrogen-Doped Carbon (Cu2O-Co3O4/CN) Composite for Efficient Water Splitting". Applied Sciences 11, nr 21 (25.10.2021): 9974. http://dx.doi.org/10.3390/app11219974.

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Herein, we report a copper oxide-cobalt oxide/nitrogen-doped carbon hybrid (Cu2O-Co3O4/CN) composite for electrochemical water splitting. Cu2O-Co3O4/CN is synthesized by an easy two-step reaction of melamine with Cu2O-Co3O4/CN composite. The designed composite is aimed to solve energy challenges by producing hydrogen and oxygen via electrochemical catalysis. The proposed composite offers some unique advantages in water splitting. Carbon imparts superior conductivity, while the water oxidation abilities of Cu2O and Co3O4 are considered to constitute a catalyst. The synthesized composite (Cu2O-Co3O4/CN) is characterized by SEM, EDS, FTIR, TEM, and AFM in terms of the size, morphology, shape, and elemental composition of the catalyst. The designed catalyst’s electrochemical performance is evaluated via linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The Cu2O-Co3O4/CN composite shows significant electrocatalytic activity, which is further improved by introducing nitrogen doped carbon (current density 10 mA cm−2, onset potential 91 mV, and overpotential 396 mV).

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Xu, Yang, Ji Chun Huang, Lin Cheng, Dian Xue Cao i Gui Ling Wang. "Ag Doped Co₃O₄ Nanowire Arrays as an Electrode Material for Electrochemical Capacitors". Applied Mechanics and Materials 268-270 (grudzień 2012): 157–63. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.157.

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Co3O4 nanowire arrays freely standing on nickel foam are prepared via a template-free growth method，and it is doped by Ag via electrodeposition method (denoted as NWA-Ag/Co3O4，NWA represents Nanowire Arrays). The morphology of NWA-Ag/Co3O4 is examined by scanning electron microscopy. The phase structure of the NWA-Ag/Co3O4 electrode is characterized by X-ray diffraction spectroscopy. The supercapacitance behavior of the NWA-Ag/Co3O4 electrodes is investigated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The results show that the nanowire arrays densely cover the nickel foam substrate and have diameters around 250 nm. The NWA-Ag/Co3O4 electrodes exhibit a specific capacitance of 1009 F g−1 at a current density of 5 mA cm-2 in 6.0 mol dm-3 KOH electrolyte. The capacitance loss is less than 6.5% after 500 charge/discharge cycles at 10 mA cm-2 and with columbic efficiency higher than 97.5%.

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Guo, Yi-Xuan, Chia-Hung Huang, Yasser Ashraf Gandomi, Chien-Te Hsieh i Wei-Ren Liu. "Synthesis and Electrochemical Properties of Co3O4@Reduced Graphene Oxides Derived from MOF as Anodes for Lithium-Ion Battery Applications". Sustainability 15, nr 6 (10.03.2023): 4988. http://dx.doi.org/10.3390/su15064988.

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In this study, we utilized nano-sized Co3O4 and reduced graphene oxides (rGOs) as composite anode materials for Li-ion batteries. The Co3O4/C composite anode was derived from ZIF67 (Zeolitic Imidazolate Framework-67) and was wrapped in rGOs through precipitation. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to identify the crystal structure, phase purity, and surface morphology of the composite. The composition-optimized Co3O4/rGO/C composite anode exhibited a reversible capacity of 1326 mAh/g in the first cycle, which was higher than that of the Co3O4/C composite anode with a capacity of 900 mAh/g at a current density of 200 mA/g. Moreover, after 80 cycles, Co3O4/rGO/C maintained a capacity of 1251 mAh/g at the same current density, which was also higher than the bare Co3O4/C composite (595 mAh/g). Additionally, the Co3O4/rGO/C composite exhibited a good capacity retention of 98% after 90 cycles, indicating its excellent cycling stability and high capacity. Therefore, the Co3O4/rGO/C electrode has great potential as a promising anode material for Li-ion batteries.

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Yurchenko, Olena, Hans-Fridtjof Pernau, Laura Engel, Benedikt Bierer, Martin Jägle i Jürgen Wöllenstein. "Impact of particle size and morphology of cobalt oxide on the thermal response to methane examined by thermal analysis". Journal of Sensors and Sensor Systems 10, nr 1 (24.02.2021): 37–42. http://dx.doi.org/10.5194/jsss-10-37-2021.

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Abstract. Differential thermal analysis (DTA) was used to examine the effect of the particle size and morphology of cobalt (III/IV) oxide (Co3O4) on its thermal response under exposure to methane (1 vol % in dry synthetic air), which is a relevant gas for the detection of combustible gases. The DTA response results from the catalytic oxidation of methane, and its characteristics should correlate with the pellistor response. Co3O4 samples differing in particle size and morphology were produced by ball milling (top-down technique) or were synthesized from precursor molecules by precipitation (bottom-up technique). The investigations carried out in dry air and a temperature range between 250 and 450 ∘C reveal that both particle size and particle shape have a considerable effect on thermal response, since the resulting layer structures and the associated surface area available for gas interaction differ. The Co3O4 catalyst, with small particles and an irregular shape, exhibits significantly higher response than milled Co3O4 samples. Comparison of DTA with the mass spectroscopy signal of CO2 evolved by the reaction verified a certain analogy between DTA measurements and the response produced by a pellistor.

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Fan, Xiao, Per Ohlckers i Xuyuan Chen. "Tunable Synthesis of Hollow Co3O4 Nanoboxes and Their Application in Supercapacitors". Applied Sciences 10, nr 4 (11.02.2020): 1208. http://dx.doi.org/10.3390/app10041208.

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Hollow Co3O4 nanoboxes constructed by numerous nanoparticles were prepared by using a facile method consisting of precipitation, solvothermal and annealing reactions. The desirable hollow structure as well as a highly porous morphology led to synergistically determined and enhanced supercapacitor performances. In particular, the hollow Co3O4 nanoboxes were comprehensively investigated to achieve further optimization by tuning the sizes of the nanoboxes, which were well controlled by initial precipitation reaction. The systematical electrochemical measurements show that the optimized Co3O4 electrode delivers large specific capacitances of 1832.7 and 1324.5 F/g at current densities of 1 and 20 A/g, and only 14.1% capacitance decay after 5000 cycles. The tunable synthesis paves a new pathway to get the utmost out of Co3O4 with a hollow architecture for supercapacitors application.

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WANG, YAN, JING HUANG, JIANLIANG CAO, GAOJIE LI i ZHANYING ZHANG. "COBALT OXIDE DECORATED FLOWER-LIKE g-C3N4 HYBRID NANOMATERIALS FOR CARBON MONOXIDE OXIDATION". Surface Review and Letters 24, nr 05 (30.09.2016): 1750058. http://dx.doi.org/10.1142/s0218625x17500585.

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Co3O4 decorated flower-like g-C3N4 hybrid nanocatalysts were successfully synthesized and prepared via a facial hydrothermal method. The composition and morphology of the as-synthesized Co3O4/g-C3N4 nanocatalysts were characterized by the techniques of XRD, FT-IR, SEM, TEM, XPS and N2-sorption. The analysis results indicated that the as-synthesized samples possess the flower-like structure, which consisted of g-C3N4 nanosheets and Co3O4 nanoparticles with the size about 25[Formula: see text]nm. The as-prepared Co3O4/g-C3N4 catalysts possess high catalytic activity and excellent stability for carbon monoxide (CO) oxidation. The total conversion of Co can be kept for more than 48[Formula: see text]h under the reaction temperature of 120[Formula: see text]C.

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Makhlouf, M. Th, B. M. Abu-Zied i T. H. Mansoure. "Direct Fabrication of Cobalt Oxide Nanoparticles Employing Sucrose as a Combustion Fuel". Journal of Nanoparticles 2013 (6.03.2013): 1–7. http://dx.doi.org/10.1155/2013/384350.

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Combustion method has been used as a fast and facile method to prepare nanocrystalline Co3O4 spinel employing sucrose as a combustion fuel. The products were characterized by thermal analyses (TGA and DTA), X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. Experimental results revealed that the molar ratio of fuel/oxidizer (F/O) plays an important role in controlling the crystallite size of Co3O4 nanoparticles. Transmission electron microscopy indicated that the crystallite size of Co3O4 nanocrystals was in the range of 13–32 nm. X-ray diffraction confirmed the formation of CoO phase with spinel Co3O4. The effect of calcination temperature on crystallite size and morphology has been, also, discussed.

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Ratchagar, V., M. Muralidharan, M. Silambarasan, K. Jagannathan, P. Kamaraj, Suresh Kumar Subbiah, P. A. Vivekanand i in. "Coprecipitation Methodology Synthesis of Cobalt-Oxide Nanomaterials Influenced by pH Conditions: Opportunities in Optoelectronic Applications". International Journal of Photoenergy 2023 (11.07.2023): 1–9. http://dx.doi.org/10.1155/2023/2493231.

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The cobalt oxide (Co3O4) nanomaterials were prepared by coprecipitation synthesis technique by maintaining the pH of the mother solution at 7, 8, and 9. The prepared nanomaterials were subjected to structural and optical characterizations, and the results were examined. The optical absorption spectral studies reveal that the two absorption bands indicate ligand–metal coordination. The photoluminescence spectra contain emission peak at 488 and 745 nm due to size and shape of the synthesized materials. The magnetic nature of the samples was identified from the hysteresis loop traced by vibrating sample magnetometry (VSM). The Fourier transform infrared (FT-IR) spectrum of Co3O4 nanomaterials reveals two sharp bands absorbed in 584 and 666 cm-1. This ascribes to the Co-O and O-Co-O stretching, respectively. As the pH of the solution varied from 7 to 10, the SEM image authenticates the transformation of Co3O4 nanomaterials morphology from spherical to cubic to agglomerated shape. From the UV-Vis spectra, two absorption bands around 473 nm and 762 nm are observed for the materials prepared at pH 7 and 8. But at pH 9, these two peaks were shifted towards higher wavelengths 515 nm and 777 nm. The observed ferromagnetic nature of Co3O4 nanomaterials clearly show the role of surface spins and surface morphology on the magnetic properties of Co3O4 nanomaterials. The cyclic voltammetry (CV) curves show the rectangular type of voltammogram. This is an indication of good charge propagation with the electrodes. The Nyquist plots of Co3O4 nanomaterials have a semicircle in the high frequency region and a vertical line in the low frequency region. The results suggest that Co3O4 is found to be a promising material for the fabrication of light-emitting diodes, solar cells, and optoelectronic devices.

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Shaheen, A., Shahid Hussain, G. J. Qiao, Mohamed H. Mahmoud, Hassan Fouad i M. S. Akhtar. "Nanosheets Assembled Co₃O₄ Nanoflowers for Supercapacitor Applications". Journal of Nanoelectronics and Optoelectronics 16, nr 9 (1.09.2021): 1357–62. http://dx.doi.org/10.1166/jno.2021.3113.

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The energy storage has become universal concern with increasing global economy and population. Therefore, it becomes a great challenge to develop renewable energy sources to meet the increasing energy demand. We have successfully synthesized Co3O4 nanoflowers by a simple hydrothermal method for supercapacitor applications. The morphology and structure were analyzed by SEM/TEM and XRD. The electrochemical properties of the Co3O4 nanoflowers of the Co3O4 nanoflowers were measured by CV, GCD, and EIS. The resulting material exhibited a specific capacitance of 3491 mF/cm2 at a current density of 20 mA/cm2 with good cyclic stability in 6 M KOH solution. Furthermore, the asymmetric supercapacitor assembled with Co3O4 nanoflowers as a positive electrode and activated carbon as a negative electrode showed high energy storage capacity (2102 mF/cm2) and good cyclic stability. Therefore, this work shows great potential of Co3O4 nanoflowers as a supercapacitor cathode material.

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Lykaki, Maria, Eleni Papista, Nikolaos Kaklidis, Sόnia Carabineiro i Michalis Konsolakis. "Ceria Nanoparticles’ Morphological Effects on the N2O Decomposition Performance of Co3O4/CeO2 Mixed Oxides". Catalysts 9, nr 3 (3.03.2019): 233. http://dx.doi.org/10.3390/catal9030233.

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Ceria-based oxides have been widely explored recently in the direct decomposition of N2O (deN2O) due to their unique redox/surface properties and lower cost as compared to noble metal-based catalysts. Cobalt oxide dispersed on ceria is among the most active mixed oxides with its efficiency strongly affected by counterpart features, such as particle size and morphology. In this work, the morphological effect of ceria nanostructures (nanorods (ΝR), nanocubes (NC), nanopolyhedra (NP)) on the solid-state properties and the deN2O performance of the Co3O4/CeO2 binary system is investigated. Several characterization methods involving N2 adsorption at −196 °C, X-ray diffraction (XRD), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (ΤΕΜ) were carried out to disclose structure–property relationships. The results revealed the importance of support morphology on the physicochemical properties and the N2O conversion performance of bare ceria samples, following the order nanorods (NR) > nanopolyhedra (NP) > nanocubes (NC). More importantly, Co3O4 impregnation to different carriers towards the formation of Co3O4/CeO2 mixed oxides greatly enhanced the deN2O performance as compared to bare ceria samples, without, however, affecting the conversion sequence, implying the pivotal role of ceria support. The Co3O4/CeO2 sample with the rod-like morphology exhibited the best deN2O performance (100% N2O conversion at 500 °C) due to its abundance in Co2+ active sites and Ce3+ species in conjunction to its improved reducibility, oxygen kinetics and surface area.

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Lyu, Xuemeng, Olena Yurchenko, Patrick Diehle, Frank Altmann, Jürgen Wöllenstein i Katrin Schmitt. "Accelerated Deactivation of Mesoporous Co3O4-Supported Au–Pd Catalyst through Gas Sensor Operation". Chemosensors 11, nr 5 (2.05.2023): 271. http://dx.doi.org/10.3390/chemosensors11050271.

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High activity of a catalyst and its thermal stability over a lifetime are essential for catalytic applications, including catalytic gas sensors. Highly porous materials are attractive to support metal catalysts because they can carry a large quantity of well-dispersed metal nanoparticles, which are well-accessible for reactants. The present work investigates the long-term stability of mesoporous Co3O4-supported Au–Pd catalyst (Au–Pd@meso-Co3O4), with a metal loading of 7.5 wt% and catalytically active mesoporous Co3O4 (meso-Co3O4) for use in catalytic gas sensors. Both catalysts were characterized concerning their sensor response towards different concentrations of methane and propane (0.05–1%) at operating temperatures ranging from 200 °C to 400 °C for a duration of 400 h. The initially high sensor response of Au–Pd@meso-Co3O4 to methane and propane decreased significantly after a long-term operation, while the sensor response of meso-Co3O4 without metallic catalyst was less affected. Electron microscopy studies revealed that the hollow mesoporous structure of the Co3O4 support is lost in the presence of Au–Pd particles. Additionally, Ostwald ripening of Au–Pd nanoparticles was observed. The morphology of pure meso-Co3O4 was less altered. The low thermodynamical stability of mesoporous structure and low phase transformation temperature of Co3O4, as well as high metal loading, are parameters influencing the accelerated sintering and deactivation of Au–Pd@meso-Co3O4 catalyst. Despite its high catalytic activity, Au–Pd@meso-Co3O4 is not long-term stable at increased operating temperatures and is thus not well-suited for gas sensors.

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Dmitriev, A. V., E. V. Vladimirova, A. P. Esaulkov, V. D. Zhuravlev, M. V. Kuznetsov i S. A. Uporov. "Morphology and Magnetic Properties of Hollow Co3O4 Spheres". Physics of the Solid State 62, nr 12 (grudzień 2020): 2332–39. http://dx.doi.org/10.1134/s1063783420120082.

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Khasu, Motlokoa, Thulani Nyathi, David J. Morgan, Graham J. Hutchings, Michael Claeys i Nico Fischer. "Co3O4 morphology in the preferential oxidation of CO". Catal. Sci. Technol. 7, nr 20 (2017): 4806–17. http://dx.doi.org/10.1039/c7cy01194f.

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Different morphologies of Co₃O₄ were synthesized and tested for their performance in the preferential oxidation (PrOx) of carbon monoxide to investigate the effect of preferentially exposed crystal planes.

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Hu, Hanmei, Junchan Xu, Weifei Wu, Dongdong Liu, Lili Zhang i Zhengxiang Hou. "Morphology Control of CoC2O4•4H2O and Co3O4 Microspheres". Asian Journal of Chemistry 25, nr 10 (2013): 5513–15. http://dx.doi.org/10.14233/ajchem.2013.oh4.

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Wang, Yangang, Yanqin Wang, Jiawen Ren, Yan Mi, Fengyuan Zhang, Changlin Li, Xiaohui Liu, Yun Guo, Yanglong Guo i Guanzhong Lu. "Synthesis of morphology-controllable mesoporous Co3O4 and CeO2". Journal of Solid State Chemistry 183, nr 2 (luty 2010): 277–84. http://dx.doi.org/10.1016/j.jssc.2009.11.009.

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Iqbal, Javed, Arshid Numan, Mohammad Omaish Ansari, Rashida Jafer, Priyanka R. Jagadish, Shahid Bashir, P. M. Z. Hasan i in. "Cobalt Oxide Nanograins and Silver Nanoparticles Decorated Fibrous Polyaniline Nanocomposite as Battery-Type Electrode for High Performance Supercapattery". Polymers 12, nr 12 (27.11.2020): 2816. http://dx.doi.org/10.3390/polym12122816.

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In this study, silver (Ag) and cobalt oxide (Co3O4) decorated polyaniline (PANI) fibers were prepared by the combination of in-situ aniline oxidative polymerization and the hydrothermal methodology. The morphology of the prepared Ag/Co3O4@PANI ternary nanocomposite was studied by scanning electron microscopy and transmission electron microscopy, while the structural studies were carried out by X-ray diffraction and X-ray photoelectron spectroscopy. The morphological characterization revealed fibrous shaped PANI, coated with Ag and Co3O4 nanograins, while the structural studies revealed high purity, good crystallinity, and slight interactions among the constituents of the Ag/Co3O4@PANI ternary nanocomposite. The electrochemical performance studies revealed the enhanced performance of the Ag/Co3O4@PANI nanocomposite due to the synergistic/additional effect of Ag, Co3O4 and PANI compared to pure PANI and Co3O4@PANI. The addition of the Ag and Co3O4 provided an extended site for faradaic reactions leading to the high specific capacity. The Ag/Co3O4@PANI ternary nanocomposite exhibited an excellent specific capacity of 262.62 C g−1 at a scan rate of 3 mV s−1. The maximum energy and power density were found to be 14.01 Wh kg−1 and 165.00 W kg−1, respectively. The cyclic stability of supercapattery (Ag/Co3O4@PANI//activated carbon) consisting of a battery type electrode demonstrated a gradual increase in specific capacity with a continuous charge–discharge cycle until ~1000 cycles, then remained stable until 2500 cycles and later started decreasing, thereby showing the cyclic stability of 121.03% of its initial value after 3500 cycles.

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Guragain, D., C. Zequine, T. Poudel, D. Neupane, R. K. Gupta i S. R. Mishra. "Facile Synthesis of Bio-Templated Tubular Co3O4 Microstructure and Its Electrochemical Performance in Aqueous Electrolytes". Journal of Nanoscience and Nanotechnology 20, nr 5 (1.05.2020): 3182–94. http://dx.doi.org/10.1166/jnn.2020.17414.

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Template-assisted facile synthesis of tubular Co3O4 microstructures and its electrochemical performance was studied to understand its use as a potential electrode material for supercapacitors. Tubular porous Co3O4 microstructures were synthesized using cotton fibers as bio-template. The as-obtained templated Co3O4 structure inherits the morphology and microstructure of cotton fiber. The electrochemical performance of the electrode made up of tubular Co3O4 structure was evaluated in 3 M KOH, NaOH, and LiOH aqueous electrolytes. The large-surface-area of tubular Co3O4 microstructure has a noticeable pseudocapacitive performance with a capacitance of 401 F/g at 1 A/g and 828 F/g at 2 mV/s, a Coulombic efficiency averaging ~100%, and excellent cycling stability with capacitance retention of about 80% after 5,000 cycles. Overall, the tubular Co3O4 microstructure displayed superior electrochemical performance in 3 M KOH electrolyte with peak power density reaching 5,500 W/kg and energy density exceeding 22 Wh/kg. The superior performance of tubular Co3O4 microstructure electrode is attributed to its high surface area and adequate pore volume distribution, which allows effective redox reaction and diffusion of hydrated ions. The facile synthesis method can be adapted for preparing various metal oxide microstructures for possible applications in catalysis, electrochemical, sensors, and fuel cells applications.

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Buizon, Lance Patrick M., i Menandro C. Marquez. "Supercapacitive Performance of Electrochemically Synthesized Samarium Cobalt Oxide Nanosheets and Nanoflowers". Materials Science Forum 1053 (17.02.2022): 125–30. http://dx.doi.org/10.4028/p-v6063a.

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High energy and power density, good life cycle are highly sought in fabricating supercapacitors. In this study, Co3O4 was successfully deposited on nickel foam via electrochemical route. The nucleation of cobalt hydroxide and its transformation to oxide were monitored using chronoamperometry and cyclic voltammetry. Changes in current density and detected redox peaks suggest the electrochemical activity of Co3O4 in an alkaline media. A specific capacitance 1291 F/g at current density of 2.5 mA/cm was achieved showing the supercapacitive property of the synthesized Co3O4. EDX results confirms the incorporation of samarium to cobalt oxide. Furthermore, scanning electron microscopy (SEM) reveals the evolution of nanosheets to nanoflowers as the electrochemical synthesis parameters were varied. The effect of morphology on the electrochemical activity and performance of Co3O4 with Samarium could pave way in developing high energy and power density electrode for supercapacitors.

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Zhao, Yan, Yucai Li, Dong Zhang, Shiwei Song, Jian Wang, Yunjie Ke, Rui Guo, Yanbo Ding i Xiandong Zhu. "Effect of Reaction Time on the Performance of Co3O4 Electrode Materials for High Performance Supercapacitors". Journal of Nanoelectronics and Optoelectronics 15, nr 12 (1.12.2020): 1429–35. http://dx.doi.org/10.1166/jno.2020.2883.

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Electrochemical performance of the material depends on the morphology and structural characteristics of the material. Co3O4 samples shows the remarkable electrochemical performance owing to the high porosity, appropriate pore size distribution and novel architecture and reaction time effect of morphology. In this work, Co3O4 nanowires grown on Ni foam have been synthesized through a facile hydrothermal approach, revealing large capacitance of 2178.4 mF cm-2 at the current density of 2 mA cm-2 and cycling stability with 79.6% capacitance retention after 6000 cycles. The as-assembled device delivers excellent electrochemical performance for high specific capacitance of 356 mF cm-2 at the current density of 2 mA cm-2 and high cycle stability.

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Custodio, Cyron L., John Lemuel G. Untalasco i Menandro C. Marquez. "Preparation of Cuprous Oxide/Cobaltous Oxide Nanostructured Composite with the Aid of Polyethylene Glycol and Ultrasonic Sound". Materials Science Forum 916 (marzec 2018): 50–54. http://dx.doi.org/10.4028/www.scientific.net/msf.916.50.

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Metal oxide semiconductors such as cobaltous oxide (Co3O4) and cuprous oxide (Cu2O) have caught the attention of many researchers due to their wide variety of applications. The attachment of Cu2O to Co3O4 was assisted by polyethylene glycol and the nanostructuring by ultrasonic sound. X-ray Diffraction (XRD) analysis of the fabricated composite reported characteristic peaks for crystalline Co3O4 and Cu2O. Results from Energy Dispersive X-ray (EDX) Spectroscopy showed the presence of cobalt, copper, and oxygen atoms which supports the result obtained in XRD. Cauliflower to nearly spherical shaped Cu2O - Co3O4 nanostructures were formed as observed in the Scanning Electron Micrographs (SEM) with a mean diameter of 0.5-1.0 μm. the shape of the composite and its surface morphology was altered with the use of different precursor materials for the synthesis of the Co3O4 seed. A blue shift in the UV-vis was observed upon the use of nitrate based precursor indicating the presence of smaller and finer particles in the composite. Overall results prove that Cu2O and Co3O4 can be synthesized using a facile solution approach with the aid of PEG and ultrasonic sound its application in the field of photocatalysis is probable.

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Untalasco, John Lemuel G., Abdul Rahman Mariscal i Menandro C. Marquez. "Morphology Induced Effect on the Electrochemical Activity of Cobaltous Oxide Nanostructures in Potassium Hydroxide and Phosphoric Acid Media". Materials Science Forum 916 (marzec 2018): 96–100. http://dx.doi.org/10.4028/www.scientific.net/msf.916.96.

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The morphology of cobalt oxide / cobaltous oxide (Co3O4) nanostructures was controlled using different seed layer concentrations and deposition time. Co3O4nanostructures were deposited on ITO glass synthesized using two step solution route. The morphological evolution of the Co3O4nanostructures has been investigated using scanning electron microscopy (SEM). This has been correlated to the electrochemical activity of the material using cyclic voltammetry (CV) in a potassium hydroxide (KOH) and phosphoric acid (H3PO4) media. Other characterization technique such as x-ray diffraction analysis (XRD) was used to verify the crystal structures of the Co3O4nanostructures. The Co3O4nanostructures revealed pronounced redox peaks in a 1M KOH electrolyte which proved its high electrochemical activity. Also the redox peaks increases with the increase in scan rate which demonstrated good reversibility of a fast charge-discharge response. Varying CV curves have been observed in a 1M H3PO4electrolyte which denotes the instability of Co3O4. The change in the morphology of Co3O4certainly affects the electrochemical property of the Co3O4. This leads to an advance study for its promising electrochemical applications for a cleaner energy.

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BOUREGUIG, K. M. E., H. TABET-DERRAZ, T. SEDDIK i M. A. BENALI. "SYNTHESIS AND CHARACTERIZATION OF (ZNO)–(CO3O4) NANOCOMPOSITE VIA SPRAY PYROLYSIS PROCESS: THE USE OF THE BRUGGEMAN MODEL ON OPTICAL PROPERTIES PREVISION". Surface Review and Letters 28, nr 07 (26.04.2021): 2150066. http://dx.doi.org/10.1142/s0218625x21500669.

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In the present paper, (ZnO)–(Co3O4) nanocomposite thin films have been prepared by using spray pyrolysis deposition on a glass substrate at 350∘C. After that, the as-obtained films have been characterized and analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the double beam UV-visible (UV-vis) spectrophotometer. Furthermore, the Bruggeman model is used to predict the evolution of the optical dielectric constant (real and imaginary parts: [Formula: see text] and [Formula: see text] to compare them with those obtained from the experimental results. The XRD pattern reveals that the nanocomposite film has diffraction peaks 2[Formula: see text], 36.95∘ corresponding respectively to the (220), (311) planes of cubic Co3O4 and another about of 2[Formula: see text] corresponding to the (101) plane of Wurtzite ZnO. Using the Debye Scherrer formula, the crystallite size of (ZnO)[Formula: see text]–(Co3O[Formula: see text] nanocomposite is found about 32[Formula: see text]nm, while the obtained thickness of this nanocomposite is about 780[Formula: see text]nm using the DekTak Stylus profilometer. Besides, the morphology analysis shows that the nanocomposite sample is well covered without holes and/or cracks and it has uniform dense grains. The evaluation of the transmittance, reflectance, refraction index, extinction coefficient, real and imaginary parts of dielectric constant as function of wavelength illustrates that the optical response of nanocomposite thin film (ZnO)[Formula: see text]–(Co3O[Formula: see text] depends on the influence of two mediums of pure materials ZnO and Co3O4 and their interaction. In addition, the direct band gap vs incident photon energy obtained from the Tauc plot equation shows that this nanocomposite has three values of band gap energy which are [Formula: see text][Formula: see text]eV, [Formula: see text][Formula: see text]eV (correspond to pure Co3O4 film) and [Formula: see text][Formula: see text]eV (correspond to pure ZnO film). Besides, the application of the Bruggeman equation indicates that the influence of the values of volume concentration and optical dielectric constant of the ingredient nanomaterials (ZnO and Co3O[Formula: see text] is significant on the value of the effective dielectric constant of nanocomposite thin film. The specific result of this study is the similarity between the spectra obtained from the Bruggeman model and the measured one, which proves that the application of this model is useful for the prediction of the optical properties of the composite.

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Ma, Maixia, Lei Wei i Fang Jin. "Porous Co3O4 nanoplatelets as efficient catalyst precursor for hydrogen generation from the hydrolysis of alkaline sodium borohydride solution". Functional Materials Letters 12, nr 01 (21.01.2019): 1850109. http://dx.doi.org/10.1142/s1793604718501096.

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For hydrogen generation from sodium borohydride hydrolysis, high-efficient catalyst precursor of porous Co3O4 nanoplatelets was successfully achieved by a combined process of hydrothermal synthesis and calcination treatment. Effects of calcination temperature on catalyst morphology and activity were mainly investigated, and the optimal condition was established. Using a reaction solution comprising 10[Formula: see text]wt.% NaBH4 and 2[Formula: see text]wt.% NaOH, the porous Co3O4 nanoplatelets exhibited a maximum hydrogen generation rate up to 19.52[Formula: see text]L[Formula: see text]min[Formula: see text] g[Formula: see text] at the temperature of 25[Formula: see text]C, which was much higher than similar Co3O4 catalyst precursors and noble metal catalysts in literature.

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Luo, Jiankang, Jun Wu, Zheng Liu, Zenghe Li i Li Deng. "Controlled Synthesis of Porous Co3O4 Nanostructures for Efficient Electrochemical Sensing of Glucose". Journal of Nanomaterials 2019 (16.09.2019): 1–7. http://dx.doi.org/10.1155/2019/8346251.

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A shape-controlled strategy was developed to synthesize porous Co3O4 nanoparticles, and the delicate morphology including nanourchins, nanowires, nanoflowers, and nanoplates could be well adjusted by adopting different anion precursors. The Co3O4 nanomaterials were further applied as the electrocatalysts for glucose detection, and the effect of nanostructure on the electrochemical performance was investigated. Results show that Co3O4 nanourchins illustrate the highest glucose sensitivity of 565 mA mM-1 cm-2 and a good linear detection ranging from 20 μM to 0.25 mM. The improved performance of obtained products was originally from the large surface area and high pore volume, which leads to a significantly increased accessibility of reactant and decreased Faradic electron transfer resistance, making it a promising candidate for glucose sensing.

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Liu, Huili, Xinglong Gou, Yi Wang, Xuan Du, Can Quan i Tao Qi. "Cauliflower-Like Co3O4/Three-Dimensional Graphene Composite for High Performance Supercapacitor Applications". Journal of Nanomaterials 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/874245.

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Cauliflower-like Co3O4/three-dimensional (3D) graphene nanocomposite material was synthesized by a facile two-step synthesis route (heat reduction of graphite oxide (GO) and hydrothermal synthesis of Co3O4). The phase composition, morphology, and structure of the as-obtained products were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). Electrochemical properties as supercapacitor electrode materials were systematically investigated by cyclic voltammetry (CV) and constant current charge-discharge tests. It was found that the Co3O4/3D graphene composite showed a maximum specific capacitance of 863 F g−1, which was obtained by means of CVs at a scan rate of 1 mV s−1in 6 M KOH aqueous solution. Moreover, the composite exhibited improved cycling stability after 1,000 cycles. The good supercapacitor performance is ascribed to the combination of 3D graphene and cauliflower-like Co3O4, which leads to a strong synergistic effect to remarkably boost the utilization ratio of Co3O4and graphene for high capacitance.

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Yang, Caiqin, Weiwei Li, Xiaowei Liu, Xiumei Song, Hongpeng Li i Lichao Tan. "Preparation of MoFs-Derived Cobalt Oxide/Carbon Nanotubes Composites for High-Performance Asymmetric Supercapacitor". Molecules 28, nr 7 (3.04.2023): 3177. http://dx.doi.org/10.3390/molecules28073177.

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Metal–organic frameworks (MOFs)-derived metallic oxide compounds exhibit a tunable structure and intriguing activity and have received intensive investigation in recent years. Herein, this work reports metal–organic frameworks (MOFs)-derived cobalt oxide/carbon nanotubes (MWCNTx@Co3O4) composites by calcining the MWCNTx@ZIF-67 precursor in one step. The morphology and structure of the composite were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) characterization. The compositions and valence states of the compounds were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Benefiting from the structurally stable MOFs-derived porous cobalt oxide frameworks and the homogeneous conductive carbon nanotubes, the synthesized MWCNTx@Co3O4 composites display a maximum specific capacitance of 206.89 F·g−1 at 1.0 A·g−1. In addition, the specific capacitance of the MWCNT3@Co3O4//activated carbon (AC) asymmetric capacitor reaches 50 F·g−1, and has an excellent electrochemical performance. These results suggest that the MWCNTx@Co3O4 composites can be a potential candidate for electrochemical energy storage devices.

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Beitollahi, Hadi, Fraiba Garkani Nejad, Somayeh Tajik i Antonio Di Bartolomeo. "Screen-Printed Graphite Electrode Modified with Graphene-Co3O4 Nanocomposite: Voltammetric Assay of Morphine in the Presence of Diclofenac in Pharmaceutical and Biological Samples". Nanomaterials 12, nr 19 (3.10.2022): 3454. http://dx.doi.org/10.3390/nano12193454.

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This work focuses on the development of a novel electrochemical sensor for the determination of morphine in the presence of diclofenac. The facile synthesis of graphene-Co3O4 nanocomposite was performed. The prepared material (graphene-Co3O4 nanocomposite) was analyzed by diverse microscopic and spectroscopic approaches for its crystallinity, composition, and morphology. Concerning the electrochemical determinations, after drop-casting the as-fabricated graphene-Co3O4 nanocomposite on the surface of a screen-printed graphite electrode (SPGE), their electrochemical performance was scrutinized towards the morphine detection. It was also found that an SPGE modified by a graphene-Co3O4 nanocomposite exhibited better electrocatalytic activity for morphine oxidation than unmodified electrode. Under optimal conditions, the differential pulse voltammetry (DPV) was employed to explore the present sensor (graphene-Co3O4/SPGE), the findings of which revealed a linear dynamic range as broad as 0.02–575.0 µM and a limit of detection (LOD) as narrow as 0.007 μM. The sensitivity was estimated to be 0.4 µM/(µA cm2). Furthermore, the graphene-Co3O4/SPGE sensor demonstrated good analytical efficiency for sensing morphine in the presence of diclofenac in well-spaced anodic peaks. According to the DPV results, this sensor displayed two distinct peaks for the oxidation of morphine and diclofenac with 350 mV potential difference. In addition, the graphene-Co3O4/SPGE was explored for voltammetric determination of diclofenac and morphine in pharmaceutical and biological specimens of morphine ampoule, diclofenac tablet, and urine, where recovery rates close to 100% were recorded for all of the samples.

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Adesuji, Elijah T., Esther Guardado-Villegas, Keyla M. Fuentes, Margarita Sánchez-Domínguez i Marcelo Videa. "Pt-Co3O4 Superstructures by One-Pot Reduction/Precipitation in Bicontinuous Microemulsion for Electrocatalytic Oxygen Evolution Reaction". Catalysts 10, nr 11 (12.11.2020): 1311. http://dx.doi.org/10.3390/catal10111311.

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Bicontinuous microemulsions (BCME) were used to synthesize hierarchical superstructures (HSs) of Pt-Co3O4 by reduction/precipitation. BCMEs possess water and oil nanochannels, and therefore, both hydrophilic and lipophilic precursors can be used. Thus, PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi were prepared (where Aq and Oi stand for the precursor present in aqueous or oily phase, respectively). The characterization of the Pt-Co3O4-HS confirmed the formation of metallic Pt and Co3O4 whose composition and morphology are controlled by the initial pH and precursor combination, determining the presence of the reducing/precipitant species in the reaction media. The electrocatalytic activity of the Pt-Co3O4-HSs for oxygen evolution reaction (OER) was investigated using linear sweep voltammetry in 0.1 M KOH and compared with Pt-HS. The lowest onset overpotentials for Pt-Co3O4-Hs were achieved with PtOi-CoOi (1.46 V vs. RHE), while the lowest overpotential at a current density of 10 mA cm−2 (η10) was obtained for the PtAq-CoAq (381 mV). Tafel slopes were 102, 89, 157 and 92 mV dec−1, for PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi, respectively. The Pt-Co3O4-HSs showed a better performance than Pt-HS. Our work shows that the properties and performance of metal–metal oxide HSs obtained in BCMEs depend on the phases in which the precursors are present.

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Sun, Guanliang, Ning Li, Dan Wang, Guanchen Xu, Xingshuang Zhang, Hongyu Gong, Dongwei Li i in. "A Novel 3D Hierarchical Plasmonic Functional Cu@Co3O4@Ag Array as Intelligent SERS Sensing Platform with Trace Droplet Rapid Detection Ability for Pesticide Residue Detection on Fruits and Vegetables". Nanomaterials 11, nr 12 (20.12.2021): 3460. http://dx.doi.org/10.3390/nano11123460.

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Rapid and effective detection of pesticide residues from complex surfaces of fruits and vegetables has important significance. Herein, we report a novel three-dimensional (3D) hierarchical porous functional surface-enhanced Raman scattering (SERS) substrate, which is fabricated by successive two-step hydrothermal synthesis strategy of silver nanoparticles (Ag NPs) and cobalt oxide nanowires (Co3O4 NWs) on the 3D copper foam framework as Cu@Co3O4@Ag-H. The strategy offers a new avenue for localized plasmonic materials distribution and construction, which exhibits better morphology regulation ability and SERS activity (or hotspots engineering) than physical spurring obtained Cu@Co3O4@Ag-S. The developed Cu@Co3O4@Ag-H possesses large surface area and rich hotspots, which contributes to the excellent SERS performance, including homogeneity (RSD of 7.8%), sensitivity (enhancement factor, EF of 2.24 × 108) and stability. The Cu@Co3O4@Ag-H not only provides plenty of Electromagnetic enhancement (EM) hotspots but also the trace detection capability for droplet rapid sensing within 2 s. Cu@Co3O4@Ag-H substrate is further developed as an effective SERS sensing platform for pesticide residues detection on the surfaces of fruits and vegetables with excellent LOD of 0.1 ppm, which is lower than the most similar reported works. This work offers new potential for bioassay, disease POCT diagnosis, national security, wearable flexible devices, energy storage and other related fields.

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Lozhkomoev, Aleksandr S., Alexander V. Pervikov, Sergey O. Kazantsev, Konstantin V. Suliz, Roman V. Veselovskiy, Andrey A. Miller i Marat I. Lerner. "Controlled Oxidation of Cobalt Nanoparticles to Obtain Co/CoO/Co3O4 Composites with Different Co Content". Nanomaterials 12, nr 15 (22.07.2022): 2523. http://dx.doi.org/10.3390/nano12152523.

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The paper studies patterns of interaction of electroexplosive Co nanoparticles with air oxygen during heating. The characteristics of Co nanoparticles and composite Co/CoO/Co3O4 nanoparticles formed as a result of oxidation were studied using transmission electron microscopy, X-ray phase analysis, thermogravimetric analysis, differential scanning calorimetry, and vibrating sample magnetometry. It was established that nanoparticles with similar morphology in the form of hollow spheres with different content of Co, CoO, and Co3O4 can be produced by varying oxidation temperatures. The influence of the composition of composite nanoparticles on their magnetic characteristics is shown.

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Nivas, Bharath, Aleena Rose, B. Shunmugapriya i T. Vijayakumar. "Investigation on Spinel Co₃O₄ Nanoparticles through Mechanochemical Technique". IOP Conference Series: Materials Science and Engineering 1219, nr 1 (1.01.2022): 012022. http://dx.doi.org/10.1088/1757-899x/1219/1/012022.

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Abstract The spinel type Cobalt Oxide (Co3O4) nanoparticles were synthesized through simple mechanochemical method. The synthesized nanoparticles were characterized through X-Ray Diffraction (XRD), Field Effect Scanning Electron Microscope (FE-SEM), Energy Dispersive spectroscopy (EDS) and Raman spectroscopy respectively. The Crystallite structure of the prepared sample was analyzed through X-Ray diffractograms. The surface morphology and the presence of elements were investigated through energy dispersive spectrum. Raman spectroscopy was utilized for recording the vibrational pattern of the sample. The cyclic voltammetry and electrochemical impedance spectroscopy reveals the good electrochemical performance of the Co3O4 nanomaterials.

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Gao, S., X. D. Li i M. Zhang. "Bionspired slippery surfaces by cluster-like ZnO@Co3O4 and its anti-corrosion performance". Digest Journal of Nanomaterials and Biostructures 16, nr 4 (grudzień 2021): 1565–73. http://dx.doi.org/10.15251/djnb.2021.164.1565.

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Herein, the super slippery surface composed of cluster-like ZnO@Co3O4 was prepared on the surface of Al alloy by a hydrothermal method. The morphology and composition of the film were characterized by SEM, XRD and XPS. In addition, electrochemical measurement results show that the impedance modulus at low frequency of cluster-like ZnO@Co3O4 SLIPS coatings was 6 orders of magnitude higher than that of the blank sample, and still 3 orders of magnitude towered over even after 28 days of immersion, which proves that the good storage capacity and long-term corrosion resistance.

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Bedair, Tarek M., Il Jae Min, Wooram Park, Yoon Ki Joung i Dong Keun Han. "Sustained drug release using cobalt oxide nanowires for the preparation of polymer-free drug-eluting stents". Journal of Biomaterials Applications 33, nr 3 (wrzesień 2018): 352–62. http://dx.doi.org/10.1177/0885328218792141.

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Polymer-based drug-eluting stents (DESs) represented attractive application for the treatment of cardiovascular diseases; however, polymer coating has caused serious adverse responses to tissues such as chronic inflammation due to acidic by-products. Therefore, polymer-free DESs have recently emerged as promising candidates for the treatment; however, burst release of drug(s) from the surface limited its applications. In this study, we focused on delivery of therapeutic drug from polymer-free (or -less) DESs through surface modification using cobalt oxide nanowires (Co3O4 NWs) to improve and control the drug release. The results demonstrated that Co3O4 NWs could be simply fabricated on cobalt–chromium substrate by ammonia-evaporation-induced method. The Co3O4 NWs were uniformly arrayed with diameters of 50–100 nm and lengths of 10 µm. It was found that Co3O4 NWs were comparatively stable without any delamination or change of the morphology under in vitro long-term stability using circulating system. Sirolimus was used as a model drug for studying in vitro release behavior under physiological conditions. The sirolimus release behavior from flat cobalt–chromium showed an initial burst (over 90%) after one day. On the other hand, Co3O4 NWs presented a sustained sirolimus release rate for up to seven days. Similarly, the polymer-less specimens on Co3O4 NWs substrates sustained sirolimus release for a longer-period of time when compared to flat Co–Cr substrates. In summary, the current approach of using Co3O4 NWs-based substrates might have a great potential to sustain drug release for drug-eluting implants and medical devices including stents.

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Tamiru Mengistu, Mintesinot, Tadele Hunde Wondimu, Dinsefa Mensur Andoshe, Jung Yong Kim, Osman Ahmed Zelekew, Fekadu Gashaw Hone, Newaymedhin Aberra Tegene, Noto Susanto Gultom i Ho Won Jang. "g -C3N4–Co3O4 Z-Scheme Junction with Green-Synthesized ZnO Photocatalyst for Efficient Degradation of Methylene Blue in Aqueous Solution". Bioinorganic Chemistry and Applications 2023 (5.06.2023): 1–14. http://dx.doi.org/10.1155/2023/2948342.

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A simple wet chemical ultrasonic-assisted synthesis method was employed to prepare visible light-driven g-C3N4-ZnO-Co3O4 (GZC) heterojunction photocatalysts. X-ray diffraction (XRD), scanning electromicroscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), ultraviolet (UV), and electrochemical impedance spectroscopy (EIS) are used to characterize the prepared catalysts. XRD confirms the homogenous phase formation of g-C3N4, ZnO, and Co3O4, and the heterogeneous phase for the composites. The synthesized ZnO and Co3O4 by using cellulose as a template show a rod-like morphology. The specific surface area of the catalytic samples increases due to the cellulose template. The measurements of the energy band gap of a g-C3N4-ZnO-Co3O4 composite showed red-shifted optical absorption to the visible range. The photoluminescence (PL) intensity decreases due to the formation of heterojunction. The PL quenching and EIS result shows that the reduction of the recombination rate and interfacial resistance result in charge carrier kinetic improvement in the catalyst. The photocatalytic performance in the degradation of MB dye of the GZC-3 composite was about 8.2-, 3.3-, and 2.5-fold more than that of the g-C3N4, g-C3N4-ZnO, and g-C3N4-Co3O4 samples. The Mott–Schottky plots of the flat band edge position of g-C3N4, ZnO, Co3O4, and Z-scheme g-C3N4-ZnO-Co3O4 photocatalysts may be created. Based on the stability experiment, GZC-3 shows greater photocatalytic activity after four recycling cycles. As a result, the GZC composite is environmentally friendly and efficient photocatalyst and has the potential to consider in the treatment of dye-contaminated wastewater.

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