Oriented Charge Flow in a Dual-Active-Site CdS Framework Enables Coupled CO2 Reduction and Biomass Alcohol Oxidation

Abstract Solar-driven conversion of CO2 into value-added chemicals provides an effective pathway for carbon resource utilization. However, the sluggish kinetics of CO2 reduction and the reliance on sacrificial electron donors limit its practical viability. Herein, we present a bifunctional photocatalyst consisting of spatially separated Ag2S and Au cocatalysts anchored on hollow CdS (Ag2S-Au/CdSH), which enables efficient concurrent CO2 photoreduction to CO and selective oxidation of aryl alcohols to benzaldehyde in a sacrificial-agent-free system. The rational integration of dual-active sites induces oriented charge flow, significantly enhancing photogenerated carrier separation and utilization, as evidenced by ultrafast spectroscopy showing extended electron lifetimes. This synergistic architecture delivers markedly higher production rates of 1.2 mmol g–1 h–1 for CO and 2.5 mmol g–1 h–1 for benzaldehyde, representing approximately 8-fold and 5-fold enhancements over pristine CdS, respectively. Comprehensive in situ spectroscopic studies combined with density functional theory calculations elucidate the distinct roles: Au sites strengthen CO2 adsorption and stabilize intermediates for reduction, while Ag2S promotes alcohol dehydrogenation. This synergistic dual-site architecture maximizes redox efficiency by matching reaction potentials and minimizing carrier recombination. This work provides mechanistic insights into catalyst design for integrated CO2 valorization and biomass upgrading, providing a basis for efficient chemical production.