Photoelectrocatalytic Oxidation of Methane into Methanol over ZnO Nanowire Arrays Decorated with Plasmonic Au Nanoparticles

The pursuit for efficient conversion of methane under ambient conditions remains a challenge. Here, we reported photoelectrocatalytic oxidation of methane into methanol over ZnO nanowire arrays (NWAs) decorated with Au nanoparticles (NPs) under simulated sunlight illumination with ambient conditions. The photoelectrochemical (PEC) performances of the ZnO and ZnO/Au photoanodes were investigated to analyze the behavior and intensity of the reaction process of methane oxidation. The Faradaic efficiency of ZnO/Au was calculated to be 32.11%, nearly three times of 11.69% for ZnO. The above results show that ZnO NWAs exhibited exceptional activity as photoanode for photoelelctrocatalytic methane oxidation, and the decoration of Au NPs further enhanced the photo-activity via the surface plasmon resonance expanding its absorption spectra to visible region. On the other hand, as a co-catalyst, Au can promote the oxidation of methane by providing the trapping sites and active sites to facilitate the separation and also suppress the recombination of photogenerated charges and the existence of Au can boost the reaction by lowering the activation energy. This research demonstrates that ZnO NWAs decorated with Au NPs hold great promise for photoelectrocatalytic methane oxidation.