Simultaneous and efficient utilization of photogenerated electrons and holes: a case of single-atom Pd-anchored CdS twins†

Abstract

Lactic acid is commonly used as a sacrificial agent while neglecting its prospects for value-added chemical conversion due to inefficient hole utilization of the photocatalyst. In the present study, we demonstrate a strategy of anchoring atomic-level Pd on CdS_x twins to maximize the utilization of electrons and holes for efficient photocatalytic hydrogen evolution coupled with pyruvate synthesis. The Pd-CdS_x-Twins photocatalyst achieved a remarkable H₂ evolution rate of 7700.25 μmol h⁻¹ with a disruptive apparent quantum efficiency of 90.2% and pyruvic acid production with a selectivity of 95.87%. The back-to-back barrier field induced by the CdS_x twins served as the prerequisite for the surface enrichment and isolated extraction of the photocarriers. TA spectroscopy, in situ XPS, and theoretical calculations proved that the Pd single atoms stabilize the twin crystal structure and provides optimal conditions for the adsorption of lactic acid molecules while promoting the extraction of holes, while the surface-enriched electrons at the S site promote hydrogen extraction. This study developed an attractive route for the utilization of photocarriers simultaneously at the reducing and oxidizing sides while expanding the economic benefits of traditional hole-sacrificial systems.