Polyvinylpyrrolidone gel based Pt/Ni(OH)2 heterostructures with redistributing charges for enhanced alkaline hydrogen evolution reaction

Abstract

Optimizing the water dissociation energy and hydrogen adsorption Gibbs free energy of active sites through redistributing charges in heterostructures is a promising strategy for improving alkaline hydrogen evolution reaction (HER). Herein, we develop a facile avenue to design a Pt/Ni(OH)₂ heterojunction on nickel foam (NF) encapsulated by polyvinylpyrrolidone (PVP) gels with a low Pt content (0.35 wt%). Impressively, the optimized sample exhibits a superior alkaline HER performance with extremely low overpotentials of 12, 37, and 60 mV at current densities of 10, 50, and 100 mA cm⁻² and a Tafel slope of 21.5 mV dec⁻¹, as well as robust durability for 50 h at 10 mA cm⁻², outperforming commercial Pt/C and most reported alkaline HER catalysts. Experimental results combined with density functional theory (DFT) calculations reveal that PVP gels can not only reconstruct the Pt/Ni(OH)₂ heterostructure to accelerate the kinetics of water dissociation and lower the hydrogen adsorption Gibbs free energy, thereby enhancing the alkaline HER, but can also elevate the stability of the Pt/Ni(OH)₂ catalyst. This work provides a promising strategy toward highly efficient and stable alkaline HER catalysis.