Construction of hierarchical CoNiMoOxHy/NF nanostructures for highly efficient urea oxidation reaction

Abstract

Urea oxidation reaction (UOR) represents a promising alternative anodic reaction for saving the energy consumption of hydrogen production by water electrolysis, while its large-scale application is still hampered by UOR catalysts with unsatisfactory performance. Herein, a hierarchical self-standing CoNiMoOxHy/NF electrode is synthesized through a mild chemical etching and deposition process with ZIF-67 nanostructure grown on Ni foam as precursor. Electrocatalytic urea oxidation with CoNiMoOxHy/NF exhibits an outstanding activity with a quite low potential of 1.27 V (vs. RHE) at the benchmark current density of 10 mA cm−2. A low Tafel slope of 36 mV dec−1 indicates its superior reaction kinetics. By comparing with CoNiOxHy/NF, the enhanced activity is mainly attributed to the faster generation kinetics for active NiOOH species and more accessible active sites numbers. This work may provide a meaningful reference for design of high performance UOR catalysts.