Nanostructured copper molybdates as promising bifunctional electrocatalysts for overall water splitting and CO 2 reduction

Overall water splitting and CO reduction are two very important reactions from the environmental viewpoint. The former produces hydrogen as a clean fuel and the latter decreases the amount of CO emissions and thus reduces greenhouse effects. Here, we prepare two types of copper molybdate, CuMoO and Cu Mo O , and electrochemically investigate them for water splitting and CO reduction. Our findings show that Cu Mo O is a better electrocatalyst for full water splitting compared to CuMoO . It provides overpotentials, which are smaller than the overpotentials of CuMoO by around 0.14 V at a current density of 1 mA cm and 0.10 V at -0.4 mA cm , for water oxidation and hydrogen evolution reactions, respectively. However, CuMoO adsorbs CO and the reduced intermediates/products more strongly than Cu Mo O . Such different behaviors of these electrocatalysts can be attributed to their different unit cells.