Boosted hydrogen evolution in alkaline media enabled by a facile oxidation-involving surface modification

Alloying Pt into Ni partially amorphous for promoted alkaline hydrogen production

Aiming at the sluggish water dissociation step in alkaline hydrogen evolution reaction (HER), the platinum-nickel alloy material (PtNi₁₀/C) featuring unique crystalline/amorphous structure supported on carbon black is deliberately designed and fabricated via a reversely rapid co-precipitation and mild thermal reduction strategy. Electrochemical results show that only 66 mV of overpotential is needed for PtNi₁₀/C to drive a current density of 10 mA cm^-2 at a lower platinum loading (8.3 μg_Pt cm-2 geo), which is much lower than that of other catalysts with a single metal source(S-Ni/C and S-Pt/C) and even the commercial Pt/C catalyst (20 wt%). The target catalyst also exhibits smaller tafel slope value (16.73 mV dec^-1) and electrochemical impedance value, enabling a fast kinetics rate for water dissociation. Partial crystallization facilitates moderate adsorption of intermediates, while the high-valence Ni(II) and Pt(II) species serve as pivotal driving force for the kinetic dissociation of water. The unique microstructure of PtNi₁₀/C shows a remarkable advantage toward HER in alkaline but acidic medium. In addition, other transition metal-based catalysts following the similar protocol are also fabricated and present varying degrees of HER performance. Hence, the facile and rapid co-precipitation/thermal reduction strategy proposed in this study provides some guidelines for designing high-efficiency alkaline HER catalysts.