N-induced compressive strain in Ni-MoO2 heterostructure with micro-nano array for improving high-current-output urea-assisted water electrolysis performance

Abstract

Developing high-performance catalysts is significant for hydrogen production from urea electrolysis, but is still an enormous challenge. Herein, we construct an N-induced compressive strain of Ni-MoO2 heterostructure with a micro-nano array structure supported on nickel foam (N-Ni-MoO2/NF) to dramatically boost the urea electrolysis performance. In 1.0 M KOH + 0.5 M urea condition, N-Ni-MoO2/NF shows low potentials for urea oxidation and hydrogen evolution reaction (UOR: E10/500/1000 = 1.351/1.415/1.439 V; HER: E−10/−500/−1000 = − 49/−242/−284 mV). Furthermore, it can obtain 1.753 V at the high-current-output of 500 mA cm−2 for urea electrolysis and stably operate for 100 h. The good UOR/HER activity and stability of N-Ni-MoO2/NF are owing to the triaxial compressive strain of Ni and MoO2, and the heterostructure between Ni and MoO2, which tune the electronic structure of N-Ni-MoO2/NF and optimize the adsorption/desorption energy of hydrogen/urea species. Besides, the micro-nano array structure accelerates the diffusion of gas/liquid and affords more active sites to improve UOR/HER performance. Therefore, this work not only fabricates a good catalyst for urea electrolysis but also provides a promising avenue for designing high-performance non-precious-metal catalytic materials at high-current-output.