Laser irradiation induced platinum-based bimetallic alloy nanoparticles in liquids for electrocatalytic hydrogen production

Designing effective catalysts with high performance for electrocatalytic hydrogen production remains a formidable challenge. Small-size bimetallic alloy nanoparticles (NPs) with the advantages of a large exposure of effective active sites and optimal geometric/electronic effects are of great interest in the field of electrocatalysis, yet a suitable strategy for synthesizing such unique structures is still highly expected. In this effort, we report a unique approach to synthesizing ultra-small bimetallic PtM (M=Ni, Co) alloy NPs (∼ 1.7 nm) on carbon supports by laser irradiation in liquids. The method is based on the effective absorption of pulse laser energy by carbon supports to generate instant high temperature, which allows the reduction of metallic ions precursors by ethanol molecules and ensures the subsequent formation of alloy NPs. The fast-cooling dynamic process stops the further growth of small-sized alloy NPs. Such bimetallic PtNi alloy NPs displayed much improved catalytic performance in the HER process. The overpotential is only 19 mV and 42 mV (10 mA cm−2) in acidic and alkaline conditions, which is much lower than that of commercial 20 % Pt/C (36 mV, 53 mV) catalyst. Density function theory calculation shows that Ni doping facilitates the hydrogen adsorption/desorption process of nearby surface Pt atoms.