Enhancing durability of Raney-Ni-based electrodes for hydrogen evolution reaction in alkaline water electrolysis: Mitigating reverse current and H2 bubble effects using a NiP protective layer

Abstract

Raney Ni (R-Ni) electrodes are used as hydrogen evolution reaction catalysts in alkaline water electrolysis (AWE). However, they are not durable because of reverse current-induced oxidation and catalyst damage from H₂ bubbles. Reverse current triggers Ni phase changes and mechanical stress, leading to catalyst delamination, while bubbles block active sites, increase resistance, and cause structural damage. These issues have been addressed individually but not simultaneously. In this study, a P-doped Ni (NiP) protective layer is electroplated on the R-Ni electrode to overcome both challenges. The NiP protective layer inhibits oxidation, reducing Ni phase changes and preventing catalyst delamination. Enhanced surface wettability minimizes nucleation and facilitates faster bubble detachment, reducing bubble-related damage. Electrochemical tests reveal that NiP/R-Ni exhibits a 26 mV lower overpotential than that of R-Ni at −400 mA cm⁻², indicating higher catalytic activity. Accelerated degradation tests (ADTs) demonstrate the retention of the NiP/R-Ni catalyst layer, with only a 25 mV increase in overpotential after ADT, which is significantly less than that of R-Ni. Real-time impedance analysis reveals the presence of small, rapidly detaching bubbles on NiP/R-Ni. Overall, the NiP protective layer on R-Ni simultaneously mitigates both reverse current and H₂ bubble-induced degradation, improving catalytic activity and durability during AWE.