Self-supporting Nickel Phosphide/Hydroxides Hybrid Nanosheet Array as Superior Bifunctional Electrode for Urea-Assisted Hydrogen Production

Urea oxidation reaction (UOR) is an important strategy to synergistically realize energy-saving hydrogen evolution reaction (HER) and urea-rich wastewater purification by replacing water oxidation in water electrolysis. However, the efficient realization of integral urea electrolysis remains challenging. Herein, a self-supporting Ni2P-Ni(OH)(2) hybrid nanosheet array on nickel foam (Ni2P@Ni(OH)(2)/NF) is designed by a simple hydrothermal accompanied by electrodeposition strategy, representing a new class of bifunctional electrodes for urea-assisted water electrolysis. The Ni2P@Ni(OH)(2)/NF reaches the current density of 100 mA cm(-2) at potentials of -0.16 V and 1.388 V, along with small Tafel slopes of 69 mV dec(-1) and 33 mV dec(-1) for HER/UOR, respectively. For the HER||UOR coupled system, the constructed electrolyzer only needs 1.38 V to realize the current density of 100 mA cm(-2) under 80 degrees C. The superior bifunctional activity of the Ni2P@Ni(OH)(2)/NF electrode is ascribed to the combined merits of the Ni2P@Ni(OH)(2) heterostructure, enriching the catalytic active sites and offering a faster charge transfer process for electrolysis. Our work provides important insights into the design of highly active bifunctional catalysts from the perspective of overall water electrolysis.