The promotional dual role of Pd Metallene in ZnCdS-based photocatalytic H2 evolution and lactic acid oxidation.

Although the construction of photocatalytic active sites is widely recognized as an effective strategy to enhance catalytic performance, achieving stable active sites remains a key challenge. This work reports a Pd metallene-loaded ZnCdS (xPZCS) photocatalyst that exhibits excellent activity for photocatalytic H2 evolution and lactic acid (LA) oxidation, attributed to the electron metal-support interaction (EMSI). Furthermore, Pd incorporation enhances the adsorption and activation capability of H2O molecules, and the reversible Pd2+/Pd0 redox cycle continuously supplies active sites and lowers the energy barrier for H2O dissociation. The optimized 10PZCS exhibites a H2 evolution rate of 22.4 mmol g-1 h-1 and an LA oxidation rate of 6.7 mmol g-1 h-1, both representing substantial improvements over pure ZCS. Through comprehensive density functional theory (DFT) calculations and photoelectrochemical analysis, the mechanism underlying the enhanced photocatalytic performance of 10PZCS is elucidated from the perspectives of reaction kinetics and active site behavior. This work harnessed the EMSI effect to design and fabricate catalytic active sites and clarifies the kinetic mechanism of LA degradation coupled with H2O-splitting H2 evolution reaction.