Currently, about 95% of H2O2 is synthesized by the anthraquinone method, which is energy-intensive, time-consuming, and produces many by-products. The electrochemical oxygen reduction reaction (ORR) is a multi-electron reaction that can form H2O through the four-electron pathway or H2O2 through the two-electron pathway. The reaction mechanism of both routes involves *OOH reaction intermediates, and whether the product is H2O or H2O2 depends on the degree of reduction of the O-O bond, and the single-electron reduction of *OOH results in the selective production of H2O2, but further reduction to H2O. Therefore, the rational design of catalysts with appropriate bond strength with *OOH is the key to achieving efficient selectivity of H2O2. Based on this,Zhang Cuijuan, Tianjin UniversitywithZou JijunAmorphous NiOX was prepared on carbon nanosheets by a simple photochemical metal-organic deposition method, which has high activity and selectivity for the production of H2O2 by 2E-orr.
Researchers systematically studied 0Changes in crystal structure, microstructure and 2-electron oxygen reduction reaction (2E-ORR) activity of the catalyst in 1 M KOH. The results show that the amorphous NiOX is highly efficient and selective for 2E-ORR with a starting potential of 076 VRHE, H2O2 selectivity was 91%, and it was at 015-0.The number of electron transfers is about 2 over a wide potential range of 60 V2. Better performance than most metal oxide-based catalysts used for 2E-orr. In addition, this property is closely related to the mesoporous structure of carbon nanosheets.
Experimental results and density functional theory (DFT) calculations show that *OOH intermediates are more likely to be adsorbed on amorphous Niox-C by termination, thereby promoting the 2E-ORR process. Amorphous Niox-C prefers to generate Ho2- at a lower overpotential through the 2E- process, resulting in higher H2O2 selectivity. In this study, the crystallinity of metal oxides and the pore structure of carbon supports were designed to improve the catalytic performance, which provides ideas for the development of high-performance and cost-effective 2E-orr electrocatalysts.
amorphous nickel oxides supported on carbon nanosheets as high-performance catalysts for electrochemical synthesis of hydrogen peroxide. acs catalysis, 2022. doi: 10.1021/acscatal.2c01829