Highly active bimetallic Pt–Cu nanoparticles for the electrocatalysis of hydrogen evolution reactions: Experimental and theoretical insight

Improving the activity and stability of Pt-based electrocatalysts is still crucial for hydrogen generation applications. In this study, we investigated the catalytic properties of Cu-doped Pt alloy nanostructures synthesized by the modified polyol method, and compared the performance of PtCu catalyst with that of commercially available Pt/C for the hydrogen evolution reaction (HER) at room temperature . Structural analyses revealed that the PtCu catalysts exhibited fcc- F m 3 ¯ m $Fm\overline{3}m$ crystal structure with an average particle size below 5 nm. The HER performance of the catalysts showed overpotential of around −1.0 V (vs. Ag/AgCl) and Pt 0.25 Cu 0.75 and Pt 0.75 Cu 0.25 catalysts exhibited enhanced performance in 1 M KOH. The Pt 0.75 Cu 0.25 catalyst exhibited distinct performance, with the highest mass activity found to be 62.80 mA mg −1 Pt . The most active Pt 0.75 Cu 0.25 catalysis for the HER process had the lowest onset potential of 0.989 V and Tafel slope of 35.5 mV dec −1 , which were an improvement compared to commercially available Pt/C catalysts. First principle DFT calculations confirmed the stabilities of Pt 1 Cu 3 , Pt 1 Cu 1 and Pt 3 Cu 1 compositions as ordered alloy structures. Nudged elastic band method calculations and the d-band model verified the higher catalytic activity of Pt–Cu nanoparticles compared to pure nanoparticles and point out the relevance of a synergistic effect of Pt and Cu atoms on water dissociation. According to DFT calculations, Cu and Pt sites significantly influenced the adsorption of H 2 O and H, respectively, for splitting water molecules. While the Pt 59 Cu 20 cluster has the highest H 2 O adsorption energy at the (100) atop site of Cu atoms, H adsorption occurs at the (111) site of Pt atoms.