Particle Size-Dependent Charge Transfer Dynamics for Boosting CO2 Photoreduction over Ag/TiO2 Heterojunction

Photocatalytic CO2 reduction (PCO2R) represents a critical pathway in renewable energy generation. Silver nanoparticles (Ag NPs) of varying sizes were deposited on TiO2 surfaces, exhibiting size-dependent catalytic activities and selectivities due to distinct charge transfer dynamics. The integration of the particle size and Ag/TiO2 Schottky junction density supplied ample active sites for CO2 reduction. Modifying the size of the Ag NPs significantly enhanced the photocatalytic performance of the Ag/TiO2 heterojunction. Notably, Ag0.5%/TiO2 showed a CO generation rate of 86.8 μmol g–1 h–1, which was 1.79 times higher than that of anatase. More importantly, Ag3.0%/TiO2 resulted in the highest selectivity of CH4 (28.1%). The particle size of Ag NPs influenced the ratio of thermal electron transfer during photoexcitation and the intermediate product pathways in the CO2 reduction process. This research provides insights and experimental foundations for particle size regulation in designing heterojunction catalysts for PCO2R.