Construction of Ni³⁺-rich nanograss arrays for boosting alkaline water oxidation

The rational design of high-efficiency electrocatalysts for application in water oxidation in alkaline media remains a great challenge. In this paper, Ni³⁺-rich nanograss-like Mo-doped Ni₃S₂/NiS/VS arrays grown on nickel foam (denoted as Mo-NiVS@NF) have been successfully constructed through a hydro/solvothermal method. Interestingly, Mo-NiVS@NF exhibits superior catalytic OER performance, needing an overpotential of 217 mV to drive a current density of 10 mA cm^-2, outperforming most previously reported NiS-based electrocatalysts. The result indicates that the Ni³⁺-rich active sites caused by the modulation of the electronic structure environment via the introduction of V and high-valency Mo play an important role in the high activity for the OER. Moreover, this catalyst shows high long-term electrochemical durability.