Mechanism investigation of PtPd decorated Zn0.5Cd0.5S nanorods with efficient photocatalytic hydrogen production combining with kinetics and thermodynamics

Different components of PtPd bimetallic cocatalysts modified Zn0.5Cd0.5S nanorods have already been designed and prepared in this study. The obtained hybrid photocatalysts were tested and characterized by XPS, ICP-OES and UV-Vis spectra, TEM and EDX tools. Such characterizations can prove the formation of PtPd bimetallic alloy particles in hybrid catalysts. Under visible light illumination, an outstanding hydrogen producing rate of 9.689 mmol·g−1·h−1 and a high AQY efficiency up to 10.43% at 420 nm are achieved in this work. In addition, thermodynamics (DFT calculations) and kinetics (Photoluminescence emission, photocurrent responses, electrochemical impedance spectroscopy and surface photovoltage spectra) investigations illustrate that PtPd bimetallic alloy has similar catalytic thermodynamic properties to Pt, which can greatly boost the charge separation and speed up the charge transfer, and decrease the activation energy of H2 generation. Notably, the calculation data suggests that Pt is thermodynamically favorable, while PtPd alloy is kinetically beneficial to H2 production, which can be ascribed to the higher activity of PtPd/Zn0.5Cd0.5S than Pt/Zn0.5Cd0.5S. This work can propose a fresh perspective for preparing high efficiency hybrid photocatalysts.