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

Abstract

A more thermodynamically favorable organic oxidation reaction should be used instead of 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 had excellent hydrogen evolution reaction (HER), and urea oxidation reaction (UOR) activities. The structure transformation and surface material changes of Ni3S2@Ni3Se2/NF during UOR were observed using the in-situ Raman method. The results reveal that the reconfiguration of Ni-based catalyst is more intensive 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 10 mA cm-2 current density. This work is a solid basis for producing hydrogen production with low energy consumption from urea-assisted hydrogen evolution.