The CoSe2 hollow cube/CoSe2 nanosheet interface catalyst for efficient electrolysis of urea–assisted hydrogen production at industrial–grade currents

Abstract

Cobalt–based catalysts are regarded as the most innovative catalyst in the urea oxidation reaction (UOR). Nevertheless, the activity limitation of Co–based catalysts by the unavoidable self–oxidation reaction of Co species (CSOR) during UOR is generally ignored. Therefore, the interface strategy was used to synthesize a CoSe2 hollow cube (HC)/CoSe2 nanosheet (NS) homogeneous interface catalyst to achieve bifunctional UOR and HER performance. In situ EIS, ex situ Raman spectroscopy, and ex situ XPS analysis verify the unique mechanism of the CoSe2 HC/CoSe2 NS interface in triggering UOR. Electrochemical activity tests demonstrated that CoSe2 HC/CoSe2 NS requires only 1.27 and 1.32 V of cell voltage to reach 10 mA cm–2 in the overall urea electrolyzer (UOR || HER) and overall human urine electrolyzer (HUOR || HER) regimes, respectively. Moreover, under an industrial–grade current (500 mA cm–2), the cell voltage can be maintained at ＜2 V for 110 h. Ultraviolet (UV) spectroscopy confirms the potential of CoSe2 HC/CoSe2 NS to degrade urea wastewater. Software simulations reveal the advantages of the unique interface strategy of CoSe2 HC/CoSe2 NS in the UOR process.