V doping: an effective strategy for enhanced alkaline seawater oxidation over NiFe layered double hydroxide

Abstract

Alkaline seawater electrolysis holds significant promise for scalable green hydrogen (H₂) production; however, the high chloride ion (Cl⁻)concentration in seawater makes the anode vulnerable to severe chemical corrosion, thereby diminishing its lifespan. Here, we demonstrate the role of V doping in boosting the efficiency and longevity of durable alkaline seawater oxidation (ASO) over a nanostructured NiFe layered double hydroxide (LDH) stabilized on a nickel foam (NF) platform. Consequently, the V-NiFe LDH/NF electrode exhibits a current density of 1000 mA cm⁻² at a minimal overpotential of 368 mV, markedly surpassing the undoped counterpart NiFe LDH/NF (1000 mA cm⁻² at 414 mV). Moreover, it maintains stable electrolysis operation over 1000 h with minimal structural degradation and significantly inhibits the generation of chlorine. During the ASO process, doped V not only promoted the surface reconstruction to generate more active sites for more efficient oxygen evolution, but also was in situ evolved into VO₄³⁻ which can effectively repel Cl⁻ and thus suppress the chlorine evolution reaction.