Surface-engineered Ni–Pt alloys as robust and cost-effective electrocatalysts for high-performance proton exchange membrane water electrolysis

Abstract

The development of efficient and durable electrocatalysts for the hydrogen evolution reaction (HER) is essential to advance proton exchange membrane water electrolysis (PEMWE), a key technology for green hydrogen production. Although Pt remains the benchmark HER catalyst, its high cost and limited durability under harsh acidic conditions hinder large-scale deployment. To address these challenges, we developed a Ni–Pt alloy catalyst via scalable electrodeposition followed by thermal annealing. Structural characterizations confirmed that thermal treatment induced Pt surface segregation, yielding a Pt-enriched shell with an Ni-rich core. This thermally induced surface reconstruction markedly reduced both surface and cohesive energies relative to pure Pt, thereby enhancing thermodynamic and structural stability. Density functional theory (DFT) calculations revealed that when Pt surface coverage approached ∼50%, the alloy surface exhibited a hydrogen adsorption free energy (ΔE_H*) close to the thermodynamic optimum. In HER testing, the heat-treated Ni_98.7Pt_1.3 catalyst (HT-Ni_98.7Pt_1.3) achieved a low overpotential of just 14 mV at −10 mA cm⁻², while maintaining robust stability over 5000 accelerated durability cycles. Moreover, when integrated into a PEMWE cell, the HT-Ni_98.7Pt_1.3 electrode delivered a record-high mass activity of 27 A mg_Pt⁻¹ at 1.7 V and sustained performance for over 200 h at 1 A cm⁻², surpassing commercial Pt/C. The synergy of scalable synthesis, structural robustness, and outstanding catalytic activity highlights surface-engineered Ni–Pt alloys as highly promising next-generation catalysts for sustainable hydrogen production.