Precise synthesis of sub-3 nm platinum-based intermetallic alloy with freeze-microwave confinement strategy for hydrogen evolution reaction

Abstract

Intermetallic compounds (IMCs) with atomically ordered crystal structures exhibit unique electrochemical catalytic properties attributed to their well–defined structure–activity correlations. However, the precise synthesis of sub–3 nm IMCs with highly active surface area remains challenging. Herein, we propose a “freeze–microwave confinement” strategy that precisely regulates crystal nucleation kinetics to widely synthesis sub–3 nm platinum–based IMCs. Significantly, the obtained sub–3 nm Pt–Fe intermetallic alloy (L12–Pt3Fe/KB) achieves overpotentials as low as 27 mV in 0.5 M H2SO4 and 35 mV in 1.0 M KOH at 10 mA cm–2, together with exceptional durability after 20 h electrolysis. More importantly, this synthesis strategy can further apply to various Pt–M alloys (M = Cr, Mn, Co, Ni and Zn), demonstrating widely applicable ability for controllable synthesis of sub–3 nm IMCs. This work provides a feasible strategy for constructing sub–3 nm IMCs and offer a fundamental understanding of crystal nucleation kinetics control toward exploring advanced Pt–based electrocatalysts.