The role of ZnO nanowires to improve methanol selectivity on Cu2O nanocubes during CO2 electroreduction

Electrochemical reduction of CO2 enables a flexible and efficient way of converting CO2 into diverse products. Cu2O is regarded as a crucial species for electrocatalytically transforming CO2 to methanol while facing challenges such as the deactivation of the catalyst and low selectivity of desired products. Therefore, the modification of Cu2O and the improvement of its catalytic activity needs to be addressed. Herein, we reported a novel synthesis of Cu2O nanocubes (Cu2O-cube) using the wet chemical method and demonstrated a Faradaic efficiency of 29.1 % for methanol. We found Cu2O (100) facet was responsible and beneficial to improve methanol production. The performance degradation at different potentials due to the deactivation of Cu2O-cube were revealed from the changes of surface morphologies by scanning electron microscope (SEM). The electrocatalytic activity of Cu2O-cube was further enhanced by embedding Cu2O-cube into ZnO nanowires (ZnO@Cu2O-cube) through drop-drying, leading to a Faradaic efficiency of 38.9 % towards methanol at - 0.45 V vs. RHE. For parallel comparison, an alternative binding form of ZnO and Cu2O was investigated through stacking Cu2O film onto ZnO nanowires (ZnO@Cu2O-film) through electrodeposition. The results elucidated that the existence of ZnO tended to suppress the production of ethanol and the binding site of ZnO-Cu2O could improve the selectivity of methanol.