D-band width of Pd metallene rationally broadened by Pt alloying enables efficient performance toward hydrogen evolution reaction.

Tailoring the electronic structure and surface adsorption characteristics of palladium (Pd) metallene is crucial for enhancing electrochemical hydrogen production via improved hydrogen evolution reaction (HER) kinetics. This study strategically integrates platinum (Pt) into the Pd metallene lattice, inducing a charge density redistribution, in which Pt withdraws electrons from Pd and facilitates d-d orbital hybridization, thereby widening the d-band of Pd. Such an electronic reconfiguration shifts the d-band center of Pd downward, weakening the binding affinity of H2O and H intermediates at Pd active sites. As a result, the optimized PdPt metallene (Pd1.5Pt1) exhibits outstanding HER performance in alkaline electrolytes, delivering an exceptionally low overpotential of 64 mV at a benchmark current density of 10 mA cm-2. This underscores the power of electronic structure engineering in designing catalytic surfaces for efficient hydrogen generation.