Hydrogen peroxide electrosynthesis with nickel foam electrodes: influence mechanism of surface oxidation

BACKGROUNDNickel foam (NF) is widely used as battery electrode matrix and electrochemical process cathode. However, the surface of NF is prone to oxidation, which may affect its ability to reduce oxygen and produce H2O2, but the influence mechanism is still unclear. In this paper, surface oxidation of the NF was regulated by pickling and drying pretreatment, and the surface oxides were characterized by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectrometry (EDS). The NF was used as the substrate, graphite powder as the catalyst, and PTFE as the binder to prepare graphite-coated NF composite electrodes. The effect of NF surface oxidation on their ability to generate H2O2 was investigated.RESULTSThe results demonstrated that after pickling and drying, the NF surface generated a large amount of NiO, which increased the charge transfer resistance of the NF by 20.3%, and accelerated further reduction decomposition of H2O2. The rotating ring-disk electrode (RRDE) tests further confirmed that NiO can reduce the two-electron oxygen reaction selectivity, which was detrimental to H2O2 electrosynthesis. The graphite-coated NF composite electrode with pristine NF as the substrate can produce 869.1 mg L-1 of H2O2 and maintain relatively good reusability.CONCLUSIONOverall, the surface oxidation of NF is not conducive to H2O2 electrosynthesis, and it is necessary to prevent oxidation during electrode preparation. This study provides a valuable reference for the preparation of NF electrodes and can promote the further study of in situ H2O2 electrosynthesis. (c) 2023 Society of Chemical Industry (SCI).