High-Density NiCu Bimetallic Phosphide Nanosheet Clusters Constructed by Cu-Induced Effect Boost Total Urea Hydrolysis for Hydrogen Production.

Abstract

The development of urea electrolysis technologies toward energy-saving hydrogen production can alleviate the environmental issues caused by urea-rich wastewater. In the current practices, the development of high-performance electrocatalysts in urea electrolysis remains critical. In this work, the NiCu-P/NF catalyst is prepared by anchoring Ni/Cu bimetallic phosphide nanosheets onto Ni foam (NF). In the experiments, the micron-sized elemental Cu polyhedron is first anchored on the surface of the NF substrate to provide more space for the growth of bimetallic nanosheets. Meanwhile, the Cu element adjusted the electron distribution within the composite and formed Ni/P orbital vacancies, which in turn accelerated the kinetic process. As a result, the optimal NiCu-P/NF sample exhibits excellent catalytic activity and cycling stability in a hybrid electrolysis system for the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). Further, the alkaline urea-containing electrolyzer is assembled with NiCu-P/NF as two electrodes reached a current density of 50 mA cm-2 with a low driving potential of 1.422 V, which outperforms the typical commercial noble metal electrolyzer (RuO2||Pt/C). Those findings suggest the feasibility of the substrate regulation strategy to increase the growth density of active species in preparation of an efficient bifunctional electrocatalyst for cracking the urea-containing wastewater.