Hollow NiMo-based nitride heterojunction with super-hydrophilic/ aerophobic surface for efficient urea-assisted hydrogen production

Hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) are key reactions of the watercycling associated catalytic process/device. The design of catalysts with a super-hydrophilic/aerophobic structure and optimized electron distribution holds great promise. Here, we have designed a threedimensional (3D) hollow Ni/NiMoN hierarchical structure with arrayed-sheet surface based on a onepot hydrothermal route for efficient urea-assisted HER based on a simple hydrothermal process. The Ni/NiMoN catalyst exhibits super-hydrophilic/aerophobic properties with a small droplet contact angle of 6.07 degrees and an underwater bubble contact angle of 155.7 degrees, thus facilitating an escape of bubbles from the electrodes. Density functional theory calculations and X-ray photoelectron spectroscopy results indicate the optimized electronic structure at the interface of Ni and NiMoN, which can promote the adsorption/desorption of reactants and intermediates. The virtues combining with a large specific surface area endow Ni/NiMoN with efficient catalytic activity of low potentials of 25 mV for HER and 1.33 V for UOR at 10 mA cmz. The coupled HER and UOR system demonstrates a low cell voltage of 1.42 V at 10 mA cm -2, which is approximately 209 mV lower than water electrolysis. (c) 2024 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.