Implanting Ni-O-VOx sites into Cu-doped Ni for low-overpotential alkaline hydrogen evolution

Abstract

Nickel-based catalysts are most commonly used in industrial alkaline water electrolysis. However, it remains a great challenge to address the sluggish reaction kinetics and severe deactivation problems of hydrogen evolution reaction (HER). Here, we show a Cu-doped Ni catalyst implanted with Ni-O-VOx sites (Ni(Cu)VOx) for alkaline HER. The optimal Ni(Cu) VOx electrode exhibits a near-zero onset overpotential and low overpotential of 21 mV to deliver -10 mA cm−2, which is comparable to benchmark Pt/C catalyst. Evidence for the formation of Ni-O-VOx sites in Ni(Cu)VOx is established by systematic X-ray absorption spectroscopy studies. The VOx can cause a substantial dampening of Ni lattice and create an enlarged electrochemically active surface area. First-principles calculations support that the Ni-O-VOx sites are superactive and can promote the charge redistribution from Ni to VOx, which greatly weakens the H-adsorption and H2 release free energy over Ni. This endows the Ni(Cu)VOx electrode high HER activity and long-term durability.