Engineering a PtAg/CdS Nano-hybrid for highly efficient light-boosted hydrogen evolution

Photo-assisted electrocatalysis has emerged as a promising strategy to break the activity limits of electrocatalysts. Here, we develop a highly efficient hybrid catalyst by loading ultra-small PtAg alloy nanoparticles (NPs) on CdS nanorods (PtAg/CdS) for hydrogen evolution reaction. The PtAg/CdS catalyst demonstrates an overpotential of 44 mV at 10 mA cm −2 in the absence of light irradiation, which significantly decreases to 17 mV under light illumination, even exceeding that of commercial Pt/C. This improved performance is attributed to the generation and effective utilization of photogenerated charges. X-ray photoelectron spectroscopy confirms the formation of electron-deficient Ptδ + sites in the nanoparticles after the introduction of Ag, whereby density functional theory calculations reveal a near-optimal hydrogen adsorption free energy. In addition to providing photogenerated charges, light also modulates the electronic structure of the PtAg alloy NPs, leading to a dual optimization of charge transfer kinetics and hydrogen adsorption energy, a synergistic effect that shows the potential of light-responsive alloy catalysts. This work provides a simple and effective interface engineering strategy to enhance photo-assisted electrocatalysis by combining electrocatalysts and light absorbers, and provides a promising way for renewable hydrogen production.