Electron modulation of cobalt carbonate hydroxide by Mo doping for urea-assisted hydrogen production

Combining urea oxidation reaction (UOR) with hydrogen evolution reaction (HER) is an effective method for energy saving and highly efficient electrocatalytic hydrogen production. Herein, molybdenum-incorporated cobalt carbonate hydroxide nanoarrays (CoxMoyCH) are designed and synthesized as a bifunctional catalyst towards UOR and HER. Benefiting from the Mo doping, the dispersed nanoarray structure and redistributed electron density, the CoxMoyCH catalyst display outstanding catalytic performance and durability for both HER and UOR, affording the overpotential of 82 mV for HER and delivering a low potential of the 1.33 V for UOR (vs. reversible hydrogen electrode, RHE) to attain a current density of 10 mA cm−2, respectively. Remarkably, when CoxMoyCH was applied as bifunctional catalyst in a two-electrode electrolyzer, a working voltage of 1.40 V is needed in urea-assisted water electrolysis at 10 mA cm−2 and without apparent decline for 40 h, outperforming the working voltage of 1.51 V in conventional water electrolysis.