Literatura académica sobre el tema "Mott-Schottky Catalyst"

Metal-supported catalyst with high activity and relatively simple preparation method is given priority to industrial production. In this work, this study reported an easily accessible synthesis strategy to prepare Mott-Schottky-type N-doped carbon encapsulated metallic Co (Co@Np+gC) catalyst by high-temperature pyrolysis method in which carbon nitride (g-C3N4) and dopamine were used as support and nitrogen source. The prepared Co@Np+gC presented a Mott-Schottky effect; that is, a strong electronic interaction of metallic Co and N-doped carbon shell was constructed to lead to the generation of Mott-Schottky contact. The metallic Co, due to high work function as compared to that of N-doped carbon, transferred electrons to the N-doped outer shell, forming a new contact interface. In this interface area, the positive and negative charges were redistributed, and the catalytic hydrogenation mainly occurred in the area of active charges. The Co@Np+gC catalyst showed excellent catalytic activity in the hydrogenation of phenylacetylene to styrene, and the selectivity of styrene reached 82.4%, much higher than those of reference catalysts. The reason for the promoted semi-hydrogenation of phenylacetylene was attributed to the electron transfer of metallic Co, as it was caused by N doping on carbon.

At present, the selective hydrogenation of α, β-unsaturated aldehydes remains a challenge due to competition between unsaturated functional groups (C=C and C=O). In this study, N-doped carbon deposited on silica-supported nickel Mott–Schottky type catalysts (Ni/SiO2@NxC) was prepared for the selective hydrogenation of cinnamaldehyde (CAL) by using the respective hydrothermal method and high-temperature carbonization method. The prepared optimal Ni/SiO2@N7C catalyst achieved 98.9% conversion and 83.1% selectivity for 3-phenylpropionaldehyde (HCAL) in the selective hydrogenation reaction of CAL. By constructing the Mott–Schottky effect, the electron transfer from metallic Ni to N-doped carbon at their contact interface was promoted, and the electron transfer was demonstrated by XPS and UPS. Experimental results indicated that by modulating the electron density of metallic Ni, the catalytic hydrogenation of C=C bonds was preferentially performed to obtain higher HCAL selectivity. Meanwhile, this work also provides an effective way to design electronically adjustable type catalysts for more selective hydrogenation reactions.

A new catalyst for green Suzuki–Miyaura cross-coupling and Mott-Schottky nitrobenzene reduction processes was prepared by thermolysis of palladium (II) poly-5-vinyltetrazolate. Heterogeneous catalyst includes Pd-nanoparticles supported on polymeric matrix. It presents recoverable and recyclable catalyst and the catalyzed reactions proceed in aqueous media at room temperature in aerobic conditions.

We demonstrate Ru nanoparticles confined on a N-doped hollow carbon matrix as a wide pH hydrogen evolution electrocatalyst. The formation of a Mott–Schottky heterojunction at the strongly coupled Ru/N-doped C interface enhances the catalysis.

Electrochemical water splitting, composed of two half reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is under intensive research to the development of H2 fuels to replace fossil fuels. Since both reactions are sluggish, catalysts are usually required to boost them. The state-of-the-art catalysts for both reactions are based on noble metals, such as Pt-based catalysts for HER and Ir or Ru-based catalysts for OER. Unfortunately, the high price and scarcity of these noble metals suppress the widespread application of water splitting. Hence, it is imperative to develop active, durable, low-cost and earth-abundant non-noble-metal electrocatalysts.[1] Among them, molybdenum carbide (Mo2C) has garnered tremendous attention as HER/OER catalysts owing to its Pt-like electronic structure and wide-pH-range catalytic performance. [2] Unfortunately, the catalytic activity of Mo2C towards HER or OER is still inferior to most advanced catalysts. One effective strategy to enhance electrocatalytic performance involves coupling and doping of Mo2C with late transition metals, e.g., Fe, Co, and Ni, which modifies electronic structure and adds active sites, metal-Mo2C interfaces. Unfortunately, similar to Mo2C, metal nanoparticles also tend to aggregate during preparation and operation. A semiconductive carbon catalyst support alleviating aggregation is usually the solution by not only conformally dispersing nanocatalysts but also providing heteroatom dopants and forming metal-semiconductor Mott-Schottky interface for further enhancing catalytic activity.[3] Besides the selection of catalysts with optimized structure and composition at the material level, the structure of electrodes derived from assembled catalysts at the device level also have a crucial influence on the water electrolyzer. Compared with powdery electrocatalysts with relatively large overpotential and easier peeling off from the electrode, self-supported hierarchical nanoarrayed electrodes are more promising for water electrolyzer because these electrodes facilitate transportation of charges and matter and thus reaction kinetics during HER/OER due to binder-free feature, catalysts-substrate seamless contact and highly exposed surface area.[4] We develop here the making of nickel-molybdenum carbide heterostructures embedded in large-area (100 cm2) hierarchically assembled nitrogen-enriched carbon, forming Mott-Schottky array on nickel foam (Ni-Mo2C/NC@NF).[5] The Ni-Mo2C/NC array is directly applied as the bifunctional catalyst with high activity and durability in alkaline electrolyte. Particularly, an extremely low overpotential of 40 mV is needed to generate hydrogen. Density functional theory calculation revealed that the formation of Ni-Mo2C Mott/NC Schottky interfaces enables favorable electronic structures for electrocatalytic water splitting. Besides, 3D hierarchical structure provides exposed active sites, facilitates mass and charge transfer, graphitic shells enhance stability. A symmetric electrolyzer using Ni-Mo2C/NC@NF generates 10 mA cm-2 at 1.59 V and operates steadily for 150 h, which even outperforms the noble metal couple, Pt/C//RuO2 for water electrolysis. The scalability, activity and durability renders Ni-Mo2C/NC@NF potential industrial application. Reference 1. M. Walter, N. Lewis et al, Chem. Rev. 2010, 110, 11, 6446. 2. M. Miao, B. Y. Xia, X. Wang et al, Chem. Eur. J. 2017, 23, 10947. 3. F. Yu, Y. Li et al Nanoscale, 2018,10, 6080. 4. H. Sun, F. Cheng., J. Chen et al. Adv. Mater. 2020, 32, 1806326. 5. Z. Xu, S. Jin, M. H. Seo, X. Wang, Appl. Catal. B: Environ. 2021, 292, 120168

This paper reports the photocatalytic decomposition of methylene blue (MB) over titania doped copper ferrite, CuFe2O4/TiO2 with 50 wt% loading, synthesized via sol-gel method. The synthesized photocatalyst was characterized by X-ray diffraction, UV-vis diffuse reflectance, and photoluminescence, Mott-Schottky (MS) analysis and linear sweep voltammetry (LSV). The catalyst loadings were varied from 0.25 – 1.0 g/L and the optimum catalyst loading found to be 0.5 g/L. At the optimum loading, the conversion achieved was 83.7%. The other loadings produced slightly lower conversions at 82.7%, 80.6% and 80.0%, corresponding to 0.25, 1 and 0.75 g/L after 3 hours of irradiation. The study on the effect of initial concentration indicated that 20 ppm as the optimum concentration, tested with 0.5 g/L catalyst loading. The spent catalyst was used for the recyclability test and demonstrated a high longevity with a degradation efficiency less than 6 % for each time interval. The novelty of this study lies on the new application of photocatalytic material, CuFe2O4/TiO2 on thiazine dye that shows remarkable activity and reusability performance under visible light irradiation. Copyright © 2019 BCREC Group. All rights reservedReceived: 15th November 2018; Revised: 14th January 2019; Accepted: 17th January 2019; Available online: 25th January 2019; Published regularly: April 2019How to Cite: Arifin, M.N., Karim, K.M.R., Abdullah, H., Khan, M.R. (2019). Synthesis of Titania Doped Copper Ferrite Photocatalyst and Its Photoactivity towards Methylene Blue Degradation under Visible Light Irradiation. Bulletin of Chemical Reaction Engineering & Catalysis, 14 (1): 219-227 (doi:10.9767/bcrec.14.1.3616.219-227) Permalink/DOI: https://doi.org/10.9767/bcrec.14.1.3616.219-227

The development of a highly efficient, visible-light responsive catalyst for environment purification has been a long-standing exploit, with obstacles to overcome, including inefficient capture of near-infrared photons, undesirable recombination of photo-generated carriers, and insufficient accessible reaction sites. Hence, novel carbon quantum dots (CQDs) modified PbBiO2I photocatalyst were synthesized for the first time through an in-situ ionic liquid-induced method. The bridging function of 1-butyl-3-methylimidazolium iodide ([Bmim]I) guarantees the even dispersion of CQDs around PbBiO2I surface, for synchronically overcoming the above drawbacks and markedly promoting the degradation efficiency of organic contaminants: (i) CQDs decoration harness solar photons in the near-infrared region; (ii) particular delocalized conjugated construction of CQDs strength via the utilization of photo-induced carriers; (iii) π–π interactions increase the contact between catalyst and organic molecules. Benefiting from these distinguished features, the optimized CQDs/PbBiO2I nanocomposite displays significantly enhanced photocatalytic performance towards the elimination of rhodamine B and ciprofloxacin under visible/near-infrared light irradiation. The spin-trapping ESR analysis demonstrates that CQDs modification can boost the concentration of reactive oxygen species (O2•−). Combined with radicals trapping tests, valence-band spectra, and Mott–Schottky results, a possible photocatalytic mechanism is proposed. This work establishes a significant milestone in constructing CQDs-modified, bismuth-based catalysts for solar energy conversion applications.

In this work, p-type CuFe2O4 was synthesized by sol gel method. The prepared CuFe2O4 was used as photocathode catalyst for photoelectrochemical (PEC) CO2 reduction. The XRD, UV-Visible Spectroscopy (UV-Vis), and Mott-Schottky (MS) experiments were done to characterize the catalyst. Linear sweep voltammetry (LSV) was employed to evaluate the visible light (λ>400 nm) effect of this catalyst for CO2 reduction. The band gap energy of the catalyst was calculated from the UV-Vis and was found 1.30 eV. Flat band potential of the prepared CuFe2O4 was also calculated and found 0.27 V versus Ag/AgCl. Under light irradiation in the CO2-saturated NaHCO3 solution, a remarkable current development associated with CO2 reduction was found during LSV for the prepared electrode from onset potential -0.89 V with a peak current emerged at -1.01 V (vs Ag/AgCl) representing the occurrence of CO2 reduction reaction. In addition, the mechanism of PEC was proposed for the photocathode where the necessity of a bias potential in the range of 0.27 to ~ -1.0 V vs Ag/AgCl was identified which could effectively inhibit the electron-hole (e-/h+) recombination process leading to an enhancement of CO2 reduction reactions. Copyright © 2018 BCREC Group. All rights reservedReceived: 4th July 2017; Revised: 5th November 2017; Accepted: 15th November 2017; Available online: 11st June 2018; Published regularly: 1st August 2018How to Cite: Karim, K.M.R., Ong, H.R., Abdullah, H., Yousuf, A., Cheng, C.K., Khan, M.K.R. (2018). Electrochemical Study of Copper Ferrite as a Catalyst for CO2 Photoelectrochemical Reduction. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (2): 236-244 (doi:10.9767/bcrec.13.2.1317.236-244)