Amorphous Nickel Oxides Supported on Carbon Nanosheets as High-Performance Catalysts for Electrochemical Synthesis of Hydrogen Peroxide

The development of high-performance yet cost-effective catalysts for electrochemical synthesis of H2O2 is a great challenge. Here, the amorphous nickel oxide NiOx supported on carbon nanosheets was prepared by the photochemical metal organic deposition method. The evolution of the crystalline structure, microstructure, and 2-electron oxygen reduction reaction (2e-ORR) activity in 0.1 M KOH was systematically investigated. The results reveal that the amorphous NiOx is highly efficient and selective toward 2e-ORR with an onset potential of 0.76 V versus reversible hydrogen electrode (RHE), 91% selectivity, and an electron transfer number of ∼2.2 over a wide potential range of 0.15–0.60 V versus RHE, which is outstanding among the metal oxide-based catalysts for 2e-ORR. Such a performance is closely associated with the mesoporous structure of the carbon nanosheets. Furthermore, the appropriate bonding strength of Ni–OH derived from the amorphous nature is crucial for the high selectivity. The theoretical calculation reveals that the *OOH intermediate prefers to adsorb on the amorphous NiOx-C by the end-on mode, facilitating the 2e-ORR process. The present amorphous NiOx loaded on carbon nanosheets can be promising electrocatalysts for synthesizing H2O2 after the stability issues are well addressed.