Boosting urea-assisted water splitting by constructing sphere-flower-like NiSe2-NiMoO4 heterostructure

Abstract

Urea-assisted water splitting is a promising hydrogen (H2) production technology, which can purify urea-rich wastewater, but the lack of cost-effective catalysts hampers its extensive application. In this work, the sphere-flower like NiSe2-NiMoO4 heterostructure catalyst self-supported on nickel foam (NiSe2-NiMoO4/NF) is successfully prepared through hydrothermal and selenization method. Only 1.32 V and −35.57 mV are required to obtain ±10 mA cm−2 for urea oxidation and hydrogen evolution reaction (UOR and HER), respectively. For a two-electrode electrolyzer, only a cell voltage of 1.37 V is required to drive 10 mA cm−2, and it shows robust durability with working continuously for 100 h at 150 mA cm−2 without obvious activity attenuation. The optimized H* and urea molecule adsorption energy on NiSe2-NiMoO4 heterostructure, novel morphology with mesoporous and self-supporting structure could be the reasons for this good performance. This work thus proposes a strategy for designing highly efficient bifunctional catalysts toward UOR and HER.