Heat-induced aliquation and phosphating of nickel as efficient catalysts for hydrogen evolution in alkaline seawater

Abstract

Developing electrolytic seawater catalysts with excellent performance is crucial for efficient hydrogen production. In this study, NiP nanoparticles anchored on NiMo oxides, denoted as NiMo-P, are synthesized through heat-induced aliquation and phosphating of Ni in the ammonium nickel molybdate. Physicochemical characterizations reveal that the abundant NiP nanoparticles are uniformly distributed on NiMo oxides. Electrochemical data reveal that a mere overpotential of 103 mV is sufficient to achieve −100 mA cm in alkaline simulated seawater, which is significantly lower than that of Pt foil (179 mV) and commercial Pt/C (165 mV). This remarkable activity observed in NiMo-P may be due to the superior water dissociation activity and hydrogen desorption ability of the NiP nanoparticles, as calculated by density functional theory, which surpasses that of Pt. Meanwhile, the NiMo-P exhibits outstanding stability, as evidenced by the chronoamperometric curve. The current remains at 98.1% of its initial value after 500 h, which can be attributed to the etching-hydrolysis method that strengthens the catalyst-carrier interaction. Besides, the inherent repulsion toward chlorine ions at the cathode effectively avoids chemical corrosion. Importantly, when coupled with the previously reported anode, NiMo-P also exhibits exceptional performance in alkaline seawater.