A heterogeneous interface on NiS@Ni3S2/NiMoO4 heterostructures for efficient urea electrolysis

Abstract

Urea electrolysis is an appealing energy conversion technology to produce hydrogen (H₂) and alleviate the problem of urea-rich wastewater treatment concurrently. In particular, electrocatalytic performance can be dramatically enhanced by rationally modulating the surface charge distribution with a well-tuned heterostructure. Herein, a heterostructure is constructed by NiMoO₄ nanosheets grown on an interior hollow NiS@Ni₃S₂ nanorods framework (NiS@Ni₃S₂/NiMoO₄). Density functional theory (DFT) calculations demonstrate that the formed heterojunction structure leads to a tailored surface charge state of NiMoO₄, with oxygen as the nucleophilic region and molybdenum as the electrophilic region, which facilitates the decomposition of urea molecules and thus significantly improves hydrogen evolution. As expected, the assembled NiS@Ni₃S₂/NiMoO₄ system substantially expedites urea electrolysis activity with a cell voltage of 1.40 V at 10 mA cm⁻², which is 200 mV less than the voltage of an overall water splitting system.