Journal articles on the topic 'Photoelectrochemical water-Oxidation (OER)'
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Jozwiak, Lukasz, Jacek Balcerzak, and Jacek Tyczkowski. "Plasma-Deposited Ru-Based Thin Films for Photoelectrochemical Water Splitting." Catalysts 10, no. 3 (March 1, 2020): 278. http://dx.doi.org/10.3390/catal10030278.
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Plasma-enhanced chemical vapor deposition (PECVD) was used to produce new Ru-based thin catalytic films. The surface molecular structure of the films was examined by X-ray photoelectron spectroscopy (XPS). To determine the electro- and photoelectrochemical properties, the oxygen evolution reaction (OER) process was investigated by linear sweep voltammetry (LSV) at pH = 13.6. It was found that Ru atoms were mainly in the metallic state (Ru0) in the as-deposited films, whereas after the electrochemical stabilization, higher oxidation states, mainly Ru+4 (RuO2), were formed. The stabilized films exhibited high catalytic activity in OER—for the electrochemical process, the onset and η10 overpotentials were approx. 220 and 350 mV, respectively, while for the photoelectrochemical process, the pure photocurrent density of about 160 mA/cm2 mg was achieved at 1.6 V (vs. reversible hydrogen electrode (RHE)). The plasma-deposited RuOX catalyst appears to be an interesting candidate for photoanode material for photoelectrochemical (PEC) water splitting.
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Shaddad, Maged N., Prabhakarn Arunachalam, Mahmoud Hezam, and Abdullah M. Al-Mayouf. "Cooperative Catalytic Behavior of SnO2 and NiWO4 over BiVO4 Photoanodes for Enhanced Photoelectrochemical Water Splitting Performance." Catalysts 9, no. 11 (October 23, 2019): 879. http://dx.doi.org/10.3390/catal9110879.
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n-BiVO4 is a favorable photoelectrode candidate for a photoelectrochemical (PEC) water splitting reaction owing to its suitable energy level edge locations for an oxygen evolution reaction. On the other hand, the sluggish water oxidation kinetics of BiVO4 photoanodes when used individually make it necessary to use a hole blocking layer as well as water oxidation catalysts to overcome the high kinetic barrier for the PEC water oxidation reaction. Here, we describe a very simple synthetic strategy to fabricate nanocomposite photoanodes that synergistically address both of these critical limitations. In particular, we examine the effect of a SnO2 buffer layer over BiVO4 films and further modify the photoanode surface with a crystalline nickel tungstate (NiWO4) nanoparticle film to boost PEC water oxidation. When NiWO4 is incorporated over BiVO4/SnO2 films, the PEC performance of the resultant triple-layer NiWO4/BiVO4/SnO2 films for the oxygen evolution reaction (OER) is further improved. The enhanced performance for the PEC OER is credited to the synergetic effect of the individual layers and the introduction of a SnO2 buffer layer over the BiVO4 film. The optimized NiWO4/BiVO4/SnO2 electrode demonstrated both enriched visible light absorption and achieves charge separation and transfer efficiencies of 23% and 30%, respectively. The photoanodic current density for the OER on optimized NiWO4/BiVO4/SnO2 photoanode shows a maximum photocurrent of 0.93 mA/cm2 at 1.23 V vs. RHE in a phosphate buffer solution (pH~7.5) under an AM1.5G solar simulator, which is an incredible five-fold and two-fold enhancement compared to its parent BiVO4 photoanode and BiVO4/SnO2 photoanodes, respectively. Further, the incorporation of the NiWO4 co-catalyst over the BiVO4/SnO2 film increases the interfacial electron transfer rate across the composite/solution interface.
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Abdullah Rashid Albalushi, Reem, and Mohd Asmadi Mohammed Yussuf. "A short review on graphene derivatives towards photoelectrochemical water splitting." E3S Web of Conferences 516 (2024): 01003. http://dx.doi.org/10.1051/e3sconf/202451601003.
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Graphene oxide is vital in photoelectrochemical (PEC) water splitting, serving as an essential photoanode material. Its semiconducting nature allows for the generation of photocurrents, promoting water oxidation at the anode and contributing to hydrogen production efficiency. Additionally, graphene is a two-dimensional carbon allotrope that has quickly emerged as a highly promising material in PEC water splitting, potentially transforming renewable energy and sustainable hydrogen generation. Graphene improves PEC water-splitting efficiency by facilitating efficient charge transport, rapid electron transfer, and effective redox reactions at the electrode-electrolyte interface. It possesses high electrical conductivity, a large specific surface area, and excellent charge carrier mobility. Its unique band structure enables efficient light absorption across a broad spectrum, including visible light, resulting in better light-to-electricity conversion. Furthermore, the inherent catalytic activity of graphene speeds up the oxygen evolution process (OER), increasing water oxidation and aiding hydrogen gas production.
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LIU, Chang, Jian Liu, and Robert Godin. "NiO Modified CN Film As Photoanodes for Photoelectrochemical Water Oxidation." ECS Meeting Abstracts MA2022-01, no. 36 (July 7, 2022): 1592. http://dx.doi.org/10.1149/ma2022-01361592mtgabs.
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The utilization of solar energy, by far the most promising renewable energy resource, remains one of the hottest topics in the 21st century. Metal-free carbon nitride (CN) material emerged as a promising water splitting photocatalyst in 2009 due to its appropriate visible light absorption, suitable optical band gap energy (2.7 eV), and facile synthesis. Though CN is one of the leading materials for solar energy conversion, this material is limited by light absorption, rapid charge recombination, and low charge carrier mobility. Metal oxide are thus investigated for counterbalancing CN’s inherent drawbacks. Interfacial CN/metal oxide heterostructures facilitate charge transportation, resulting in improved sunlight-driven water splitting process. In this work, low-cost NiO transition-metal oxide material was applied to speed up the sluggish kinetics of the oxygen evolution reaction (OER). Typically, CN modification is achieved by traditional hydrothermal approach, while its disadvantages such as uneven coating particle size and heterogenous distribution are becoming increasingly apparent. Aiming at a conformal morphology, atomic layer deposition (ALD) is developed as the state-of-the-art technique. It has boosted the depositing accuracy by achieving precisely depositing thickness and extremely homogenous surface. In our process, a uniform CN film was deposited on FTO substrates using a dipping-drying technique with a hot saturated thiourea aqueous solution followed by a thermal treatment. Then plasma-enhanced atomic layer deposition (PEALD) was used to modify the CN film with a thin layer of NiO. PEALD controls the NiO modification on a fine-scale, allowing to with deposit a nanoscale NiO layer on the CN surface while exposing adequate CN photoreactive sites. According to our results, the modified NiO/CN heterostructure has the potential to improve photoelectrochemical water oxidation as a photoanode in alkaline solution. From the morphology side, the NiO loaded flake-like CN creates relatively high specific area for OER. Then we investigated the photo-process kinetic using a series of optical and spectroelectrochemcial techniques. Optical absorption is enhanced, showing stronger visible light absorption up to 700 nm. Fast charge separation is suggested in photoluminescence (PL) characterization. Superior (photo)electrochemical (PEC) activity is foreseen through PEC and EC measurements. To conclude, this is the first time we succeed to modify the CN film with the ALD technique for solar-driven water oxidation, and has the highly possibility of reaching the photo(electro)chemical performance new level.
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Xi, Lifei, and Kathrin Lange. "Surface Modification of Hematite Photoanodes for Improvement of Photoelectrochemical Performance." Catalysts 8, no. 11 (October 26, 2018): 497. http://dx.doi.org/10.3390/catal8110497.
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Solar water splitting is a promising method for producing renewable fuels. Thermodynamically, the overall water splitting reaction is an uphill reaction involving a multiple electron transfer process. The oxygen evolution reaction (OER) has been identified as the bottleneck process. Hematite (α-Fe2O3) is one of the best photoanode material candidates due to its band gap properties and stability in aqueous solution. However, the reported efficiencies of hematite are notoriously lower than the theoretically predicted value mainly due to poor charge transfer and separation ability, short hole diffusion length as well as slow water oxidation kinetics. In this Review Article, several emerging surface modification strategies to reduce the oxygen evolution overpotential and thus to enhance the water oxidation reaction kinetics will be presented. These strategies include co-catalysts loading, photoabsorption enhancing (surface plasmonic metal and rare earth metal decoration), surface passivation layer deposition, surface chemical etching and surface doping. These methods are found to reduce charge recombination happening at surface trapping states, promote charge separation and diffusion, and accelerate water oxidation kinetics. The detailed surface modification methods, surface layer materials, the photoelectrochemical (PEC) performances including photocurrent and onset potential shift as well as the related proposed mechanisms will be reviewed.
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Peng, Ben, Mengyang Xia, Chao Li, Changshen Yue, and Peng Diao. "Network Structured CuWO4/BiVO4/Co-Pi Nanocomposite for Solar Water Splitting." Catalysts 8, no. 12 (December 17, 2018): 663. http://dx.doi.org/10.3390/catal8120663.
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A network structured CuWO4/BiVO4 nanocomposite with a high specific surface area was prepared from CuWO4 nanoflake (NF) arrays via a method that combined drop-casting and thermal annealing. The obtained CuWO4/BiVO4 exhibited high catalytic activity toward photoelectrochemical (PEC) water oxidation. When cobalt phosphate (Co-Pi) was coupled with CuWO4/BiVO4, the activity of the resulting CuWO4/BiVO4/Co-Pi composite for the oxygen evolution reaction (OER) was further improved. The photocurrent density (Jph) for OER on CuWO4/BiVO4/Co-Pi is among the highest reported on a CuWO4-based photoanode in a neutral solution. The high activity for the PEC OER was attributed to the high specific surface area of the composite, the formation of a CuWO4/BiVO4 heterojunction that accelerated electron–hole separation, and the coupling of the Co-Pi co-catalyst with CuWO4/BiVO4, which improved the charge transfer rate across composite/solution interface.
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Li, Chao, and Peng Diao. "Boosting the Activity and Stability of Copper Tungsten Nanoflakes toward Solar Water Oxidation by Iridium-Cobalt Phosphates Modification." Catalysts 10, no. 8 (August 10, 2020): 913. http://dx.doi.org/10.3390/catal10080913.
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Severe interfacial electron–hole recombination greatly limits the performance of CuWO4 photoanode towards the photoelectrochemical (PEC) oxygen evolution reaction (OER). Surface modification with an OER cocatalyst can reduce electron–hole recombination and thus improve the PEC OER performance of CuWO4. Herein, we coupled CuWO4 nanoflakes (NFs) with Iridium–cobalt phosphates (IrCo-Pi) and greatly improved the photoactivity of CuWO4. The optimized photocurrent density for CuWO4/IrCo-Pi at 1.23 V vs. reversible hydrogen electrode (RHE) rose to 0.54 mA∙cm−2, a ca. 70% increase over that of bare CuWO4 (0.32 mA∙cm−2). Such improved photoactivity was attributed to the enhanced hole collection efficiency, which resulted from the reduced charge-transfer resistance via IrCo-Pi modification. Moreover, the as-deposited IrCo-Pi layer well coated the inner CuWO4 NFs and effectively prevented the photoinduced corrosion of CuWO4 in neutral potassium phosphate (KPi) buffer solution, eventually leading to a superior stability over the bare CuWO4. The facile preparation of IrCo-Pi and its great improvement in the photoactivity make it possible to design an efficient CuWO4/cocatalyst system towards PEC water oxidation.
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Xing, Zhuo, Hengyi Wu, Liang Wu, Xuening Wang, Huizhou Zhong, Feng Li, Jinchao Shi, et al. "A multifunctional vanadium-doped cobalt oxide layer on silicon photoanodes for efficient and stable photoelectrochemical water oxidation." Journal of Materials Chemistry A 6, no. 42 (2018): 21167–77. http://dx.doi.org/10.1039/c8ta07552b.
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Streibel, Verena, Johanna Leonie Schönecker, Laura Idoya Wagner, Thomas Maier, Teodor Apetrei, Johanna Eichhorn, Saswati Santra, and Ian D. Sharp. "Zirconium (Oxy)Nitrides for (Photo)Electrochemical Applications." ECS Meeting Abstracts MA2023-02, no. 47 (December 22, 2023): 2303. http://dx.doi.org/10.1149/ma2023-02472303mtgabs.
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Transition metal (TM) nitrides are an emerging class of (photo)electrocatalytic materials that have recently received growing research interest.1,2 In general, nitrogen-poor TM nitrides are usually refractory materials with metallic character while nitrogen-rich nitrides often possess semiconducting character.3 Hence, while the former are potential electrocatalyst candidates, the latter may qualify as photoelectrode absorber materials. For example, ZrN has recently been proposed as an electrocatalyst for both the electrochemical nitrogen4 and oxygen5 reduction reactions (ORR and NRR), while Zr3N4 and also Zr2N2O have been suggested as potential photoanode materials in photoelectrochemical water oxidation.2 In this contribution, we test these hypotheses regarding the (photo)electrochemical characteristics of Zr-based (oxy)nitrides by experiment. To this end, we investigate reactively sputtered thin films for the electrochemical NRR/ORR and the photoelectrochemical oxygen evolution reaction (OER). Previous experiments on Ta-based nitrides have shown that addition of oxygen during the reactive sputter process is necessary to access higher metal oxidation states.6 As we introduce controlled amounts of oxygen at otherwise fixed deposition conditions, we observe a transition from metallic ZrN to a disordered nitrogen-rich ZrxNy to a crystalline bixbyite-type Zr2N2O to nitrogen-doped cubic ZrO2. Crystalline Zr3N4 was not accessible under the used experimental conditions. In our experiments, we observe a lack of electrocatalytic activity for ZrN in NRR and ORR and instabilities of the disordered nitrogen-rich ZrxNy in the photoelectrochemical OER. Introducing more oxygen into the structure, however, leads to a more stable crystalline structure (Zr2N2O), the opening of a band gap in the visible range, and the emergence of photoelectrochemical activity for oxidation reactions. Based on chopped linear sweep voltammetry measurements, we show that Zr2N2O films are photoactive for the OER in alkaline electrolyte with low onset potentials, indicating an overall favorable band alignment of the material with respect to the water oxidation and reduction potentials. While the observed photocurrents are still about one order of magnitude lower than for the benchmark oxynitride photoanode TaON, further material optimization could potentially close this gap and provide a materials system functioning as sustainable photoanode. References 1 W. Sun, C.J. Bartel, E. Arca, S.R. Bauers, B. Matthews, B. Orvañanos, B.R. Chen, M.F. Toney, L.T. Schelhas, W. Tumas, J. Tate, A. Zakutayev, S. Lany, A.M. Holder, and G. Ceder, Nat. Mater. 18, 732 (2019). 2 Y. Wu, P. Lazic, G. Hautier, K. Persson, and G. Ceder, Energy Environ. Sci. 6, 157 (2013). 3 A. Salamat, A.L. Hector, P. Kroll, and P.F. McMillan, Coord. Chem. Rev. 257, 2063 (2013). 4 Y. Abghoui, A.L. Garden, J.G. Howalt, T. Vegge, and E. Skúlason, ACS Catal. 6, 635 (2016). 5 Y. Yuan, J. Wang, S. Adimi, H. Shen, T. Thomas, R. Ma, J.P. Attfield, and M. Yang, Nat. Mater. 19, (2019). 6 C.M. Jiang, L.I. Wagner, M.K. Horton, J. Eichhorn, T. Rieth, V.F. Kunzelmann, M. Kraut, Y. Li, K.A. Persson, and I.D. Sharp, Mater. Horizons 8, 1744 (2021).
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Nath, Narayan Chandra Deb, Hyunwoong Park, and Jae-Joon Lee. "(Invited) Electrodeposition of CuxCo3-XO4 As Highly Efficient Oxygen Evolution Catalyst." ECS Meeting Abstracts MA2018-01, no. 31 (April 13, 2018): 1881. http://dx.doi.org/10.1149/ma2018-01/31/1881.
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The oxygen evolution reaction (OER) plays an important role in many energy conversion devices including photoelectrochemical cells, fuel cells and rechargeable metal air batteries. It proceeds through a four electron transfer water oxidation process and it is kinetically sluggish. It requires considerable high electrochemical overpotential to fill the significant losses in the energy conversion efficiency. The efficient and stable electrocatalyst can facilitate the sluggish kinetics of the OER. Earth-limited and expensive metal oxides such as RuO2, IrO2, PtO2 are considered as most active OER electrocatalysts. However, their high-cost and low-availability limits their large-scale applications. Therefore, there is a great interest in developing OER catalysts based on earth-abundant metals such as copper (Cu) and cobalt (Co). Recently, the spinel-type CuCo2O4 exhibited promising OER activities and corrosion stability in alkaline media. However, preparation of the CuCo2O4 by the traditional solid-phase method involves high-temperature sintering and grinding. It gives the particles with limited electroactive surface area and inadequate electron transport property between the CuCo2O4 particles and collecting substrate. In the present study, we prepared a series of flower-like nanostructured CuxCo3-xO4 with high electroactive surface area via very simple and straightforward electrochemical deposition method and applied as catalysts for OER activity. They showed very promising OER activities and stabilities at low overpotentials due to their high electroactive surface area and high intrinsic electrical conductivity.
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García-Tecedor, Miguel, Alejandro García-Eguizábal, Mariam Barawi Moran, Miguel Gomez‐Mendoza, Imdea Energy, Ignacio J. Villar-Garcia, Marta Liras, and Victor A. de la Peña O'Shea. "Transition Metal Doped BiVO4 Photoanodes: A Mechanistic Study." ECS Meeting Abstracts MA2023-02, no. 47 (December 22, 2023): 2279. http://dx.doi.org/10.1149/ma2023-02472279mtgabs.
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BiVO4 has emerged as one of the most promising materials to fabricate efficient photoanodes for photoelectrochemical (PEC) solar water splitting. BiVO4 is an n-type semiconductor, with a 2.4 eV bandgap and a theoretical solar to hydrogen (STH) efficiency of 9.2% with a maximum photocurrent of 7.5 mA cm2 under AM 1.5 G illumination, low overpotential and favourable band-edge positions towards the Oxygen Evolution Reaction (OER).1 However, BiVO4 also presents poor electron transport, high surface recombination and slow water oxidation kinetics. Hence, enormous efforts have been made in the past few years to mitigate these drawbacks through different approaches such as nanostructuring,2 doping,3 heterostructuring,4 and the use of efficient co-catalysts.5 The present study proposes a transition metal doping (Ni, Fe and Co) of BiVO4 photoelectrodes that boosts their water oxidation performance. The origin of this enhanced performance towards Oxygen Evolution Reaction (OER) was studied by a combination of a suite of structural, chemical, and mechanistic advanced characterization techniques including X-Ray Photocurrent Spectroscopy, Electrochemical Impedance Spectroscopy and Transient Absorption Spectroscopy, among others. [1] J. Li and N. Wu, Catal. Sci. Technol., 2015, 5, 1360–1384. [2] S. P. Berglund, D. W. Flaherty, N. T. Hahn, A. J. Bard and C. B. Mullins, J. Phys. Chem. C, 2011, 115, 3794–3802. [3] S. K. Pilli, T. E. Furtak, L. D. Brown, T. G. Deutsch, J. A. Turner and A. M. Herring, Energy Environ. Sci., 2011, 4, 5028–5034. [4] J. Su, L. Guo, N. Bao and C. A. Grimes, Nano Lett., 2011, 11, 1928–1933. [5] D. K. Lee and K.-S. Choi, Nat. Energy, 2018, 3, 53–60.
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Niu, Yakun, Yi Zhou, Ping Niu, Haiyan Shen, and Ying Ma. "Effects of Ti Doping on Hematite Photoanodes: More Surface States." Journal of Nanoscience and Nanotechnology 19, no. 6 (June 1, 2019): 3437–46. http://dx.doi.org/10.1166/jnn.2019.16091.
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Ti doped hematite photoanodes have been intensively investigated due to their excellent activity for photoelectrochemical water oxidation. However, little attention has been paid to the doping effect on the photocurrent onset potential of hematite and the underlying mechanism. In this paper, Ti doped hematite nanorod arrays were successfully prepared through a facile treatment of hematite with TiCl3 solution. The photocurrent of the Ti doped hematite photoanode increases by three times, and its onset potential shifts more positively as compared with that of the undoped one. Electrochemical analyses were employed to unravel the mechanism of anodic shift of the onset potential. Cyclic voltammograms and electrochemical impedance spectra confirmed that more surface states were formed in Ti doped hematite than the undoped one. As a result, lower activity towards oxygen evolution reaction (OER) and increased electron–hole recombination after light on/off in low potential region were observed in Ti doped hematite. It is concluded that these doping induced surface states may be a hindrance to charge transfer and the onset potential of Ti doped hematite shifts anodically.
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Balu, Sridharan, Harikrishnan Venkatesvaran, Kuo-Wei Lan, and Thomas C.-K. Yang. "Synthesis of Highly Efficient (0D/1D) Z-Scheme CdS-NPs@ZnO-NRs Visible-Light-Driven Photo(electro)catalyst for PEC Oxygen Evolution Reaction and Removal of Tetracycline." Catalysts 12, no. 12 (December 7, 2022): 1601. http://dx.doi.org/10.3390/catal12121601.
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Herein, we synthesized the cadmium sulfide nanoparticles (CdS-NPs) coated zinc oxide nanorods (ZnO-NRs) core-shell like CdS-NPs@ZnO-NRs heterojunction for photo(electro)chemical applications. The CdS-NPs and ZnO-NRs were synthesized through a simple hydrothermal path. The physicochemical and optoelectronic properties of the as-prepared catalysts are characterized by various spectroscopy techniques, such as FTIR, XRD, SEM, TEM, EDX, VB-XPS, DRS, and PL. The photocatalytic performances of the CdS-NPs@ZnO-NRs catalyst were evaluated by photodegradation of tetracycline (TC) in aqueous media under visible-light irradiation, which demonstrated 94.07 % of removal (k’ = 0.0307 min−1) within 90 min. On the other hand, the photoelectrochemical (PEC) water-oxidation/oxygen-evolution reaction (OER) was performed, which resulted in the photocurrent density of 3.002 mA/cm2 and overpotential (at 2 mA/cm2) of 171 mV (vs RHE) in 1.0 M KOH under AM 1.5G illumination. The reactive species scavenging experiment demonstrates the significant contributions of photogenerated holes towards TC removal. Furthermore, the Z-scheme CdS-NPs@ZnO-NRs core-shell heterojunction exhibits high efficiency, recyclability, and photostability, demonstrating that the CdS-NPs@ZnO-NRs is a robust photo(electro)catalyst for visible-light PEC applications.
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Stettner, Jochim, Tim Wiegmann, Canrong Qiu, Finn Reikowski, Mathilde Bouvier, Ivan Pacheco, Manon Bertram, et al. "Operando Surface X-Ray Diffraction Studies of Co Oxide Catalyst Films for Electrochemical Water Splitting." ECS Meeting Abstracts MA2023-02, no. 55 (December 22, 2023): 2697. http://dx.doi.org/10.1149/ma2023-02552697mtgabs.
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The need for environmental friendly and sustainable energy conversion has triggered renewed interest into the electrochemical and photoelectrochemical splitting of water. A key challenge in this field is the development of economically viable electrocatalyst materials for the oxygen evolution reaction (OER). Transition-metal oxide catalysts, in particular the cobalt (hydr)oxide materials, have been found as promising candidates, since they are earth-abundant, efficient and scalable over a wide range of electrochemical conditions [1]. They present good catalytic properties and stability in alkaline solution under ambient conditions. Although a wide variety of different catalysts with rather diverse nanoscale morphologies have been synthesized and studied, the atomic scale surface structure usually is still unknown or poorly defined. This makes it difficult to compare their electrocatalytic activity and correlate it with ab initio theoretical studies, which hinders the development of clear structure-reactivity relationships and unambiguous determination of the OER reaction mechanism. We presentsystematic comparative studiesof structurally well-defined, 18-35nm thick Co3O4 films, prepared by electrodeposition or physical vapor deposition (PVD) on Au(111), Au(100) and Ir(100) single crystals. In all cases a well ordered epitaxial Co3O4(111) arrangement results, but the film morphology differs substantially, as shown by AFM and surface X-ray diffraction (SXRD). In order to elucidate the quantitative relationship between the catalyst surface structure and the OER reactivity, synchrotron-based operando SXRD and electrochemical measurements were performed simultaneously under reaction conditions, using a dedicated operando cell which allows massive gas evolution and current densities of up to 150 mA/cm2 [2,3]. We find that the Co3O4(111) layers prepared by PVD on Ir(100) stay perfectly stable in the pre-OER and OER potential regime, whereas all electrodeposited films exhibit reversible changes in the oxide structure and oxidation state, in agreement with a previous study of Co3O4 catalysts [2]. Specifically, we observe the reverse formation of an ultrathin X-ray-amorphous CoOx(OH)y skin layer above 1 V vs. RHE and the gradual buildup of tensile lattice strain in the underneath, remaining Co3O4 layer with increasing potential. These structural changes occur for all electrodeposited samples, albeit to a different extent, depending on the film morphology [3]. Studying the relationship between the effective thickness of this skin layer and the OER reactivity, we found clear evidence that the entire skin layer is a three dimensional OER zone, which strongly exceeds one monolayer. Our results suggest that even subtle changes of the surface morphology have large influence on the OER activity of the Co3O4 catalyst, which may be expected also for other spinel-type transition metal oxides. On the one hand, this reveals that great care as to be taken in comparing the OER activity of differently prepared catalysts. On the other hand, these observations may provide a base for targeted preparation of highly reactive oxide catalysts. [1] C. C. L. McCrory et al., Journal of the American Chemical Society 2015, 137, 4347. [2] F. Reikowski, et al., ACS Catalysis, 2019, 9, 3811. [3] T. Wiegmann, et al., ACS Catalysis, 2022, 12, 256.
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Solarska, Renata Anna, Krzysztof Bienkowski, and Monika Arasimowicz. "(Invited) Development and Integration of Heterojunctions for Enhanced Solar Energy Conversion." ECS Meeting Abstracts MA2018-01, no. 31 (April 13, 2018): 1841. http://dx.doi.org/10.1149/ma2018-01/31/1841.
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Photoelectrochemical applications of semiconducting metal oxides are continuously growing and gaining a considerable interest in view of enhanced production of renewable energy. However, overcoming intrinsic limitations of well-known and recognized towards specific action semiconducting oxides such as iron oxide, titanium oxide, tungsten oxide or copper oxide requires development of new nanoarchitectures. Given the band edges positions are not always suitable for a desired solar driven process, of primary importance is to enhance the intrinsic properties of the building materials and couple them with a catalytic modification of the surface. Therefore, efforts including development of new hetero-nanostructures and their implementation to the different type of junctions employed in solar arrangements, are continuously devoted to minimization of the required bias voltage, improvement of light capture or charge separation and collection. Recently, these approaches allowed to develop a highly active catalytic system consisting of a mesoporous semiconducting metal oxide (tungsten trioxide, titanium dioxide or iron oxide) and attached thereto polyoxometalate based WOC. The stable and reproducible water splitting photocurrents reached 4.5 mA cm-2 for WO3 based working system and were attained at standard conditions. In this scenario, incorporated in small amount polyoxometalates act as highly effective molecular OER catalysts leading to very large enhancement of water oxidation photocurrents [1]. These findings have also been transferred to other semiconducting systems relying onto engineered low sub-stoichiometric disorder in TiO2 or hexagonal WO3 conjugated to copper (I) oxide, enhanced and stabilized by the presence of heterojunction [2]. A special attention will be paid to their stabilization, intentional modification, as well as optimization of experimental conditions, permitting control and diversification of the reaction products. [1] M. Sarnowska, K. Bienkowski, P. J. Barczuk, R. Solarska, J. Augustynski, Adv. Energy Mater. (2016), 1600526 [2] E. Szaniawska, K. Bienkowski, I. Rutkowska, P. Kulesza, R. Solarska, Cat. Today (2017) doi.org/10.1016/j.cattod.2017.05.099
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Sunkara, Mahendra Kumar, and Sonia Calero. "(Invited) Novel Band-Gap Engineered III-V Alloys for Unassisted Water Photoelectrolysis." ECS Meeting Abstracts MA2018-01, no. 31 (April 13, 2018): 1885. http://dx.doi.org/10.1149/ma2018-01/31/1885.
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Photoelectrochemical water splitting cells comprising the alloys of III-V semiconductors hold record solar-to-hydrogen efficiencies. However, the performance of state-of-the art III-V alloy-based single absorber devices, particularly of InGaP2, InGaAs, GaPN, and GaAsN, comes short of unassisted water due to a) inadequate alignment of band edges with respect to the HER and OER redox potentials, b) insufficient photovoltage to favor charge separation at the solid electrolyte liquid junction, and/or iii) recombination. In order to circumvent these limitations considerable research efforts have been directed at creating more complex architectures involving e.g. tandem cells, nanostructures, and buried junctions to correctly position the bands and provide enough driving force to surmount overpotentials and the 1.23 eV energetic barrier of the water splitting reactions. Therefore, developing novel III-V photoabsorbers with adequate band energetics is key to conceiving simpler, yet efficient single semiconductor PEC cells for production of solar fuels at a competitive cost. First-principles DFT+U calculations incorporating the local density approximation and generalized gradient approximation have shown that incorporation of Sb narrows the band gap in Ga(Sbx)N1-x and changes the electronic band gap from indirect to direct in GaSbP. Theoretical computations predict that, with band gaps in the order of 2 eV, these materials straddle the potential window for water oxidation and proton reduction in acidic solution. Single crystalline films of these two materials have been deposited by halide/hydride vapor phase epitaxy and metalorganic chemical vapor deposition systems, in a wide range of Sb incorporation without phase segregation. Experimental results corroborate the significant band gap reduction in GaSbN from 3.4 to 1.5 eV(Fig 1a) and suggest the conversion of excitonic transitions in the electronic band structure of GaSbP (Fig 1b) as determined by Tauc plot analysis of diffuse reflectance data and low temperature photoluminescence spectroscopy. Electrodes comprising Ga(Sbx)N1-x and Ga(Sbx)P1-x have been benchmarked employing 2- and 3-electrode standard methods for assessment of their characteristic attributes, i.e. flat-band and onset potentials, photovoltage, zero-bias photocurrent density, fill factors, carrier concentrations, and most importantly, their ability for gas evolution by in situ fluorescence probing. This presentation will highlight recent advances in the understanding of the inter-relationship of processing/synthesis, material structure and photoelectrochemical properties of this new class of materials. Also, preliminary data on un-assisted photoactivity involving p-Si cathode and n-type GaSbP anode will be presented. Acknowledgements: Financial support from US Department of Energy (DE-FG02-07ER46375) and NSF (DMS1125909). Collaborations with Dr. Todd Deutsch & Dr. James Young of NREL, and Dr. Madhu Menon of Univ. of Kentucky are acknowledged. Also acknowledge contributions of prior PhD students (Alejandro Garcia and Swathi Sunkara). References: R.M. Sheetz, E. Richter, A.N. Andriotis, C. Pendyala, M.K. Sunkara and M. Menon, “Visible light absorption and large band gap bowing in dilute alloys of gallium nitride with antimony”, Phys. Rev. B, 84, 075304 (2011) S. Sunkara, V.K. Vendra, J.B. Jasinski, T. Deutsch, A.N. Andriotis, K. Rajan, M. Menon and M.K. Sunkara, "New Visible Light Absorbing Materials for Solar Fuels, Ga(Sbx)N1-x”, Adv. Mater., 26 (18), 2878-2882 (2014) H. Russell et al., “Direct Band Gap Gallium Antimony Phosphide GaSbxP1-x Alloys”, Scientific Reports 6, (2016).
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Fominski, Vyacheslav, Roman Romanov, Dmitry Fominski, Alexey Soloviev, Oxana Rubinkovskaya, Maxim Demin, Ksenia Maksimova, Pavel Shvets, and Aleksandr Goikhman. "Performance and Mechanism of Photoelectrocatalytic Activity of MoSx/WO3 Heterostructures Obtained by Reactive Pulsed Laser Deposition for Water Splitting." Nanomaterials 10, no. 5 (April 30, 2020): 871. http://dx.doi.org/10.3390/nano10050871.
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This work studies the factors that affect the efficiency of the photoelectrochemical hydrogen evolution reaction (HER) using MoSx/WO3 nano-heterostructures obtained by reactive pulsed laser deposition (RPLD) on glass substrates covered with fluorinated tin oxide (FTO). Another focus of the research is the potential of MoSx nanofilms as a precursor for MoOz(S) nanofilms, which enhance the efficiency of the photo-activated oxygen evolution reaction (OER) using the MoOz(S)/WO3/FTO heterostructures. The nanocrystalline WO3 film was created by laser ablation of a W target in dry air at a substrate temperature of 420 °C. Amorphous MoSx nanofilms (2 ≤ x ≤ 12) were obtained by laser ablation of an Mo target in H2S gas of varied pressure at room temperature of the substrate. Studies of the energy band structures showed that for all MoSx/WO3/FTO samples, photo-activated HER in an acid solution proceeded through the Z-scheme. The highest photoelectrochemical HER efficiency (a photocurrent density ~1 mA/cm2 at a potential of ~0 V under Xe lamp illumination (~100 mW/cm2)) was found for porous MoS4.5 films containing the highest concentration of catalytically active sites attributed to S ligands. During the anodic posttreatment of porous MoSx nanofilms, MoOz(S) films with a narrow energy band gap were formed. The highest OER efficiency (a photocurrent density ~5.3 mA/cm2 at 1.6 V) was detected for MoOz(S)/WO3/FTO photoanodes that were prepared by posttreatment of the MoSx~3.2 precursor. The MoOz(S) film contributed to the effective photogeneration of electron–hole pairs that was followed by the transport of photoelectrons from MoOz(S) into the WO3 film and the effective participation of holes possessing strong oxidation ability in the OER on the surface of the MoOz(S) film.
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Lee, Dong Ki, and Kyoung-Shin Choi. "(Invited) A New Strategy to Enhance Long-Term Photostability of BiVO4 Photoanodes for Solar Water Splitting." ECS Meeting Abstracts MA2018-01, no. 31 (April 13, 2018): 1847. http://dx.doi.org/10.1149/ma2018-01/31/1847.
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As the performance of photoelectrodes used in in a photoelectrochemical cell (PEC) for water splitting continues to improve, concurrently improving their photostabilities has become an important issue. In this presentation, we report a new strategy to suppress photocorrosion of photoelectrodes using a BiVO4 photoanode as an example. BiVO4 has been recently identified as a promising oxide-based photoanodes for solar water splitting owing to many of its uniquely advantageous features. Anodic photocorrosion of BiVO4 photoanodes involves the loss of V5+ from the BiVO4 lattice by dissolution. Any composition change caused by the anodic photocorrosion of BiVO4 must be coupled with the oxidation of one or more of the elements present in BiVO4. Since V5+ in the BiVO4 lattice cannot be further oxidized, the dissolution of V5+ must be linked with the photooxidation of Bi3+ and/or lattice O2- ions. We show that the use of a V5+-saturated electrolyte, which inhibits the photooxidation-coupled dissolution of BiVO4, can slow down the rate of photocorrosion considerably and serve as a simple yet effective method to suppress anodic photocorrosion of BiVO4. We also discovered that the V5+ species in the solution can incorporate into the oxygen evolution catalyst (OEC) layer present on the BiVO4 surface during water oxidation, further enhancing water oxidation kinetics. The effect of the V5+ species in the electrolyte on both the long-term photostability of BiVO4 and the performance of the OEC layer will be discussed in detail.
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Alqahtani, M., S. Ben-Jabar, M. Ebaid, S. Sathasivam, P. Jurczak, X. Xia, A. Alromaeh, et al. "Gallium Phosphide photoanode coated with TiO2 and CoOx for stable photoelectrochemical water oxidation." Optics Express 27, no. 8 (March 18, 2019): A364. http://dx.doi.org/10.1364/oe.27.00a364.
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Wang, Meng, Lan Wu, Feng Zhang, Lili Gao, Lei Geng, Jiabao Ge, Kaige Tian, et al. "Doping with Rare Earth Elements and Loading Cocatalysts to Improve the Solar Water Splitting Performance of BiVO4." Inorganics 11, no. 5 (May 7, 2023): 203. http://dx.doi.org/10.3390/inorganics11050203.
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BiVO4 is a highly promising material for Photoelectrochemical (PEC) water splitting photoanodes due to its narrow band gap value (~2.4 eV) and its ability to efficiently absorb visible light. However, the short hole migration distance, severe surface complexation, and low carrier separation efficiency limit its application. Therefore, in this paper, BiVO4 was modified by loading CoOOH cocatalyst on the rare earth element Nd-doped BiVO4 (Nd-BiVO4) photoanode. The physical characterization and electrochemical test results showed that Nd doping will cause lattice distortion of BiVO4 and introduce impurity energy levels to capture electrons to increase carrier concentration, thereby improving carrier separation efficiency. Further loading of surface CoOOH cocatalyst can accelerate charge separation and inhibit electron–hole recombination. Ultimately, the prepared target photoanode (CoOOH-Nd-BiVO4) exhibits an excellent photocurrent density (2.4 mAcm−2) at 1.23 V versus reversible hydrogen electrode potential (vs. RHE), which is 2.67 times higher than that of pure BiVO4 (0.9 mA cm−2), and the onset potential is negatively shifted by 214 mV. The formation of the internal energy states of rare earth metal elements can reduce the photoexcited electron–hole pair recombination, so as to achieve efficient photochemical water decomposition ability. CoOOH is an efficient and suitable oxygen evolution cocatalyst (OEC), and OEC decoration of BiVO4 surface is of great significance for inhibiting surface charge recombination. This work provides a new strategy for achieving effective PEC water oxidation of BiVO4.
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Klahan, Kanokwan, Gabriel Loget, and Pichaya Pattanasattayavong. "Copper‐Nickel Alloy Modified‐Silicon Photoanodes for Photoelectrochemical Water Oxidation and Urea Oxidation." ChemNanoMat, May 14, 2024. http://dx.doi.org/10.1002/cnma.202400036.
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The development of silicon (Si) photoanodes for photoelectrochemical (PEC) oxidation is highly crucial for the progress of solar‐driven hydrogen production. Apart from the typical water oxidation reaction or oxygen evolution reaction (OER), the urea oxidation reaction (UOR) is gaining more attention due to favorable thermodynamics. In this work, we study Si photoanodes modified with electrodeposited copper‐nickel (CuNi) alloy for OER and UOR. The optimized photoanodes exhibit a low onset potential of 1.15 V vs reversible hydrogen electrode (RHE) and a current density of 6 mA cm‐2 at 1.23 V vs RHE (the thermodynamic potential for water oxidation) for OER. Further, CuNi alloy‐modified photoanodes can drive the UOR at a lower onset potential (1.05 V vs RHE) and generate a higher current density of 31 mA cm‐2 at 1.23 V vs RHE. Importantly, the CuNi alloy can extend the stability for UOR under PEC conditions when compared to a planar Ni film deposited by a vacuum‐based process. This work demonstrates that CuNi alloy can further improve the properties of inhomogeneous metal‐insulator‐semiconductor Si photoanodes which can be efficiently utilized for both OER and UOR.
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Chen, Biyi, Dan Li, Xiaojie Wu, Shuang Deng, Longhua Li, and Weidong Shi. "Ultrathin black phosphorus as pivotal hole extraction layer and oxidation evolution co-catalyst boosting solar water oxidation." Inorganic Chemistry Frontiers, 2022. http://dx.doi.org/10.1039/d2qi00120a.
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Inefficient minority carrier extraction and sluggish oxygen evolution reaction (OER) kinetics are two principal contradictions restricting photoelectrochemical water oxidation. Here, the aforementioned restrictions could be simultaneously alleviated by coupling ultrathin...
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Ahmed, Amira Y., Dattatray Sadashiv Dhawale, and Tarek Kandiel. "Transparent Iron-incorporated Nickel Hydroxide Electrocatalyst for Efficient Water Oxidation." Sustainable Energy & Fuels, 2023. http://dx.doi.org/10.1039/d3se00527e.
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Developing transparent electrocatalyst electrodes for oxygen evolution reaction (OER) is indispensable for fabricating a tandem photoelectrochemical device for solar hydrogen production. Herein, we developed a facile solution-based method for depositing...
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Amano, Fumiaki, Shimpei Nomura, Chihiro Tateishi, and Satoshi Nakayama. "Clarification of Photoelectrochemical Oxygen Evolution Sites in TiO2 Nanotube Array Electrodes by PbO2 Deposition Method." Journal of The Electrochemical Society, January 19, 2023. http://dx.doi.org/10.1149/1945-7111/acb4be.
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Abstract TiO2 nanotube (TNT) photoanodes exhibit activity and stability for the oxygen evolution reaction (OER) by photoelectrochemical water oxidation. However, the location of the OER site by the photogenerated holes has not been clarified for the TNT photoanodes, unlike well-studied macrocrystalline photocatalysts. In this study, we performed reactions of TNT photoanodes in a 0.1 M Pb(NO3)2 under UV irradiation. The photoelectrochemically deposited PbO2 particles were observed through scanning electron microscopy in the backscattered electron mode. We found that β-PbO2 was deposited on the nanotubes with photocurrent decay and that the reaction site was located on the upper part (~1 µm) of the TNT array with ~3 µm length. The photocurrent decay implies the selective deposition of PbO2 on the catalytic site for water oxidation. The PbO2 nanoparticles were deposited on the inner and outer surfaces of the tube walls. This result is consistent with the mechanism of charge separation at the space charge layers formed on both surfaces of the walls. We also confirmed that the OER site changes depending on the wavelength of the incident light due to the change in the light penetration depth.
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Nie, Zhiwei, Boyang Zhang, Jifang Zhang, Kejing Hu, Guijun Ma, and Nan Yang. "The Role of Cobalt‐Based Cocatalysts on BiVO4 for Photoelectrochemical Water Oxidation." ChemCatChem, February 29, 2024. http://dx.doi.org/10.1002/cctc.202301683.
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Cocatalysts play a key role in enhancing activity of photoelectrodes while the study of their interaction remains a challenge. Here, we decoupled the relationship between oxygen evolution reaction (OER) performance and photoelectrochemical (PEC) water oxidation performance by modifying an identical BiVO4 with different cobalt‐based OER catalysts including Co, CoO, Co3O4, and Co4N. The electrochemical OER activities of these cobalt specimens were quite similar. Their anodic photocurrent density followed an order of: Co4N > Co > Co3O4 > CoO after loading on the BiVO4 electrode. The kinetics process and energy band diagram were analyzed, revealing that the interface between different cobalt specimens and BiVO4 electrode influenced the charge recombination and transfer. Accordingly, we propose a corresponding structural model, which shows that the cocatalysts consist of inner part for interface modulation and the outer layer for catalysis. The present work reveals the vital role of contact interface between cocatalysts and semiconductors, and more attention should be paid when selecting the cocatalysts
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Choi, Sungkyun, Sol A. Lee, Jin Wook Yang, Woonbae Sohn, Jaehyun Kim, Woo Seok Cheon, Jaemin Park, et al. "Boosted Charge Transport through Au-modified NiFe Layered Double Hydroxide on Silicon for Efficient Photoelectrochemical Water Oxidation." Journal of Materials Chemistry A, 2023. http://dx.doi.org/10.1039/d3ta03075j.
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Designing an appropriate oxygen evolution reaction (OER) catalyst for photoelectrochemical (PEC) water splitting is an urgent issue for providing high-efficiency solar to hydrogen energy production. Transition metals have been central...
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Yin, Zhuocheng, Kaini Zhang, Yuchuan Shi, Yiqing Wang, and Shaohua Shen. "An Interface‐cascading Silicon Photoanode with Strengthened Built‐in Electric Field and Enriched Surface Oxygen Vacancies for Efficient Photoelectrochemical Water Splitting." Chemistry – A European Journal, January 10, 2024. http://dx.doi.org/10.1002/chem.202303895.
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To promote interfacial charge transfer process and accelerate surface water oxidation reaction kinetics for photoelectrochemical (PEC) water splitting over n‐type Silicon (n‐Si) based photoanodes, herein, starting with surface stabilized n‐Si/CoOx, a NiOx/NiFeOOH composite overlayer was coated by atomic layer deposition and spray coating to fabricate the multilayer structured n‐Si/CoOx/NiOx/NiFeOOH photoanode. Encouragingly, the obtained n‐Si/CoOx/NiOx/NiFeOOH photoanode exhibits much increased PEC activity for water splitting, with onset potential cathodically shifted to ~0.96 V vs. RHE and photocurrent density increased to 22.6 mA cm‐2 at 1.23 V vs. RHE for OER, as compared to n‐Si/CoOx, even significantly surpassing the counterpart n‐Si/CoOx/NiOx/FeOOH and n‐Si/CoOx/NiOx/NiOOH photoanodes. Photophysical and electrochemical characterizations evidence that the deposited CoOx/NiOx/NiFeOOH composite overlayer would create large band bending and strong built‐in electric field at the introduced cascading interfaces, thereby producing a large photovoltage of 650 mV to efficiently accelerate charge transfer from the n‐Si substrate to the electrolyte for water oxidation. Furthermore, the surface oxygen vacancy enriched NiFeOOH overlayer could effectively catalyze the water oxidation reaction by thermodynamically reducing the energy barrier of rate determining step for OER.
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Matsumoto, Yoshiyasu, Kengo Nagatsuka, Yuichi Yamaguchi, and Akihiko Kudo. "Understanding the reaction mechanism and kinetics of photocatalytic oxygen evolution on CoOx-loaded bismuth vanadate." Journal of Chemical Physics 159, no. 21 (December 4, 2023). http://dx.doi.org/10.1063/5.0177506.
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Photocatalytic water splitting for green hydrogen production is hindered by the sluggish kinetics of oxygen evolution reaction (OER). Loading a co-catalyst is essential for accelerating the kinetics, but the detailed reaction mechanism and role of the co-catalyst are still obscure. Here, we focus on cobalt oxide (CoOx) loaded on bismuth vanadate (BiVO4) to investigate the impact of CoOx on the OER mechanism. We employ photoelectrochemical impedance spectroscopy and simultaneous measurements of photoinduced absorption and photocurrent. The reduction of V5+ in BiVO4 promotes the formation of a surface state on CoOx that plays a crucial role in the OER. The third-order reaction rate with respect to photohole charge density indicates that reaction intermediate species accumulate in the surface state through a three-electron oxidation process prior to the rate-determining step. Increasing the excitation light intensity onto the CoOx-loaded anode improves the photoconversion efficiency significantly, suggesting that the OER reaction at dual sites in an amorphous CoOx(OH)y layer dominates over single sites. Therefore, CoOx is directly involved in the OER by providing effective reaction sites, stabilizing reaction intermediates, and improving the charge transfer rate. These insights help advance our understanding of co-catalyst-assisted OER to achieve efficient water splitting.
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Pal, Debashish, Debayan Mondal, Dipanjan Maity, Debasis De, Mukhesh K. G., Ashutosh K. Singh, and Gobinda Gopal Khan. "Single-Atomic Ruthenium Dispersion Promoting Photoelectrochemical Water Oxidation Activity of CeOx Catalyst on Doped TiO2 Nanorods Photoanode." Journal of Materials Chemistry A, 2024. http://dx.doi.org/10.1039/d3ta05922g.
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Recently, various single-atom (SA) catalyst-coupled TiO2 nanostructures have been designed for photocatalytic hydrogen evolution. However, TiO2 is a well-established photoanode capable of solar-driven oxygen evolution reaction (OER). Selection and design...
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Shao, Bo, Linxing Meng, Fang Chen, Jianyuan Wang, Wei Zhai, and Liang Li. "Ultrasound Induces Local Disorder of FeOOH on CdIn2S4 Photoanode for High Efficiency Photoelectrochemical Water Oxidation." Small, March 27, 2024. http://dx.doi.org/10.1002/smll.202401143.
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AbstractThe regulation of the crystal structure of oxygen evolution cocatalyst (OEC) is a promising strategy for enhancing the photoelectrochemical efficiency of photoanodes. However, the prevailing regulating approach typically requires a multistep procedure, presenting a significant challenge for maintaining the structural integrity and performance of the photoanode. Herein, FeOOH with a local disordered structure is directly grown on a CdIn2S4 (CIS) photoanode via a simple and mild sonochemical approach. By modulating the localized supersaturation of Ni ions, ultrasonic cavitation induces Ni ions to participate in the nucleation and growth of FeOOH clusters to cause local disorder of FeOOH. Consequently, the local disordered FeOOH facilitates the exposure of additional active sites, boosting OER kinetics and extending charge carrier lifetimes. Finally, the optimal photoanode reaches 4.52 mA cm−2 at 1.23 VRHE, and the onset potential shifts negatively by 330 mV, exhibiting excellent performance compared with that of other metal sulfide‐based photoelectrodes reported thus far. This work provides a mild and controllable sonochemical method for regulating the phase structure of OECs to construct high‐performance photoanodes.
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Cao, Guangming, Yanjie Liu, Jundie Hu, Jiafu Qu, Zhichao Zhang, Xianqiang Xiong, Wei Sun, Xiaogang Yang, and Chang Ming Li. "Alternating 3rd‐ to 2nd‐order charge reaction kinetics on bismuth vanadate photoanodes with ultrathin bismuth metal‐organic‐frameworks." ChemPhysChem, March 10, 2024. http://dx.doi.org/10.1002/cphc.202400141.
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The most challenging obstacle for photocatalysts to efficiently harvest solar energy is the sluggish surface redox reaction (e.g., oxygen evolution reaction, OER) kinetics, which is believed to originate from interface catalysis rather than the semiconductor photophysics. In this work, we developed a light‐modulated transient photocurrent (LMTPC) method for investigating surface charge accumulation and reaction on the W‐doped bismuth vanadate (W:BiVO4) photoanodes during photoelectrochemical water oxidation. Under illuminating conditions, the steady photocurrent corresponds to the charge transfer rate/kinetics, while the integration of photocurrent (I~t) spikes during the dark period is regarded as the charge density under illumination. Quantitative analysis of the surface hole densities and photocurrents at 0.6 V vs. reversible hydrogen electrode results in an interesting rate‐law kinetics switch: a 3rd‐order charge reaction behavior appeared on W:BiVO4, but a 2nd‐order charge reaction occurred on W:BiVO4 surface modified with ultrathin Bi metal‐organic‐framework (Bi‐MOF). Consequently, the photocurrent for water oxidation on W:BiVO4/Bi‐MOF displayed a 50% increment. The reaction kinetics alternation with new interface reconstruction is proposed for new mechanism understanding and/or high‐performance photocatalytic applications.
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Dadashi Radvar, Sahand, Amin Yourdkhani, and Reza Poursalehi. "A facile route for decoration of hematite photoanodes by transition metal hydroxide co‐catalysts." Journal of the American Ceramic Society, April 21, 2024. http://dx.doi.org/10.1111/jace.19826.
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AbstractEarth‐abundant α‐Fe2O3 (hematite) is a convincing photoanode for photoelectrochemical (PEC) water splitting; however, its intrinsic properties of inferior charge transfer and sluggish water oxidation kinetics limit its performance. Here, we report a straightforward decoration method for transition metal hydroxides to accelerate the oxygen evolution reaction (OER) of hematite photoanodes grown by electric field‐assisted liquid phase deposition (EA‐LPD). The investigations revealed that Co(OH)2 acts as a superior co‐catalyst compared with hydroxides of Mn, Fe, Co, Ni, and Zn. EA‐LPD‐grown hematite photoanode loaded with cobalt hydroxide exhibited an excellent PEC performance. A photocurrent density of 0.93 mA.cm−2 at 1.23 V versus reversible hydrogen electrode was achieved for the modified hematite, ∼3 times more than that of pristine hematite, and a cathodic shift of 100 mV for the onset potential was observed. The proposed simple and cost‐effective co‐catalyst loading strategy provides a high degree of freedom in the design of co‐catalysts with a complex chemical composition comprising transition metal oxyhydroxides and hydroxides on different photoanodes for more efficient charge carrier separation for the PEC applications.
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Singh, Harish, Taishi Higuchi-Roos, Fabrice Roncoroni, David Prendergast, and Manashi Nath. "Solar enhanced oxygen evolution reaction with transition metal telluride." Frontiers in Chemistry 12 (April 26, 2024). http://dx.doi.org/10.3389/fchem.2024.1381144.
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The photo-enhanced electrocatalytic method of oxygen evolution reaction (OER) shows promise for enhancing the effectiveness of clear energy generation through water splitting by using renewable and sustainable source of energy. However, despite benefits of photoelectrocatalytic (PEC) water splitting, its uses are constrained by its low efficiency as a result of charge carrier recombination, a large overpotential, and sluggish reaction kinetics. Here, we illustrate that Nickel telluride (NiTe) synthesized by hydrothermal methods can function as an extremely effective photo-coupled electrochemical oxygen evolution reaction (POER) catalyst. In this study, NiTe was synthesized by hydrothermal method at 145°C within just an hour of reaction time. In dark conditions, the NiTe deposited on carbon cloth substrate shows a small oxygen evolution reaction overpotential (261 mV) at a current density of 10 mA cm–2, a reduced Tafel slope (65.4 mV dec−1), and negligible activity decay after 12 h of chronoamperometry. By virtue of its enhanced photo response, excellent light harvesting ability, and increased interfacial kinetics of charge separation, the NiTe electrode under simulated solar illumination displays exceptional photoelectrochemical performance exhibiting overpotential of 165 mV at current density of 10 mA cm-2, which is about 96 mV less than on dark conditions. In addition, Density Functional Theory investigations have been carried out on the NiTe surface, the results of which demonstrated a greater adsorption energy for intermediate -OH on the catalyst site. Since the -OH adsorption on the catalyst site correlates to catalyst activation, it indicates the facile electrocatalytic activity of NiTe owing to favorable catalyst activation. DFT calculations also revealed the facile charge density redistribution following intermediate -OH adsorption on the NiTe surface. This work demonstrates that arrays of NiTe elongated nanostructure are a promising option for both electrochemical and photoelectrocatalytic water oxidation and offers broad suggestions for developing effective PEC devices.
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Park, Youngsun, Xiaoyan Jin, Jeiwan Tan, Hyungsoo Lee, Juwon Yun, Sun Ihl Ma, Gyumin Jang, et al. "High-Performance Sb2S3 Photoanode Enabling Iodide Oxidation Reaction for Unbiased Photoelectrochemical Solar Fuel Production." Energy & Environmental Science, 2022. http://dx.doi.org/10.1039/d1ee02940a.
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The traditional photoelectrochemical (PEC) tandem configuration of hydrogen evolution reaction and oxygen evolution reaction (OER) demands a considerable potential of 1.8 V due to theoretical water splitting potential as well...
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Chen, Runyu, Linxing Meng, Changda Wang, Weiwei Xu, Yulong Huang, Li Song, and Liang Li. "Nonstoichiometric In–S group yielding efficient carrier transfer pathway in In2S3 photoanode for solar water oxidation." SusMat, February 4, 2024. http://dx.doi.org/10.1002/sus2.185.
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AbstractThe construction of high‐efficiency photoanodes is essential for developing outstanding photoelectrochemical (PEC) water splitting cells. Furthermore, insufficient carrier transport capabilities and sluggish surface water oxidation kinetics limit its application. Using a solvothermal annealing strategy, we prepared a nonstoichiometric In–S (NS) group on the surface of an In2S3 photoanode in situ and unexpectedly formed a type II transfer path of carrier, thereby reducing the interfacial recombination and promoting the bulk separation. First‐principles calculations and comprehensive characterizations demonstrated NS group as an excellent oxygen evolution cocatalyst (OEC) that effectively facilitated carrier transport, lowered the surface overpotential, increased the surface active site, and accelerated the surface oxygen evolution reaction kinetics by precisely altering the rate‐determining steps of * to *OH and *O to *OOH. These synergistic effects remarkably enhanced the PEC performance, with a high photocurrent density of 5.02 mA cm−2 at 1.23 V versus reversible hydrogen electrode and a negative shift in the onset potential by 310 mV. This work provides a new strategy for the in situ preparation of high‐efficiency OECs and provides ideas for constructing excellent carrier transfer and transport channels.
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Wang, Taotao, Hongyun Cao, Jinbao Wu, Mohsen Golbon Haghighi, Roya Sedghi, and Pingwu Du. "Boosting Photoelectrochemical Water Oxidation Performance of Nanoporous BiVO4 via Dual Cocatalysts Cobaloxime and Ni-OEC Modification." Journal of Physical Chemistry C, June 28, 2022. http://dx.doi.org/10.1021/acs.jpcc.2c03482.
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