Engineering high-valence nickel sites in Ni3S2/Ni3Se2 architectures enabling urea-assisted hydrogen evolution reactions

A more thermodynamically favorable organic oxidation reaction should be used instead of the oxygen evolution reaction (OER) to avoid high power consumption. Implementing this technology requires the development of stable, highly efficient, and inexpensive electrocatalysts. This study reports the synthesis of a heterogeneous catalyst composed of Ni3S2 nanowires and Ni3Se2 nanosheets on nickel foam (Ni3S2@Ni3Se2/NF) using hydrothermal in situ growth and electrodeposition. The prepared Ni3S2@Ni3Se2/NF heterostructures demonstrate excellent hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) activities. The structural transformation and surface material changes of Ni3S2@Ni3Se2/NF during the UOR were observed using the in situ Raman method. The results reveal that the reconfiguration of the Ni-based catalyst is more intense and stronger in the UOR process, producing more Ni2+–O (β-Ni(OH)2) and thereby generating more Ni3+–O (γ-NiOOH) via electrochemical oxidation. Furthermore, compared to other catalysts recently described, when Ni3S2@Ni3Se2/NF was used as both the anode and cathode in the battery, it only required a low 1.45 V voltage to attain a current density of 10 mA cm−2. This work is a solid basis for producing hydrogen with low energy consumption from urea-assisted hydrogen evolution.