Advanced Catalyst for CO2 Photo-Reduction: From Controllable Product Selectivity by Architecture Engineering to Improving Charge Transfer Using Stabilized Au Clusters

Abstract

Despite enormous progress and improvement in photocatalytic CO2 reduction reaction (CO2RR), the development of photocatalysts that suppress H2 evolution reaction (HER), during CO2RR, remains still a challenge. Here, new insight is presented for controllable CO2RR selectivity by tuning the architecture of the photocatalyst. Au/carbon nitride with planar structure (p Au/CN) showed high activity for HER with 87% selectivity. In contrast, the same composition with a yolk@shell structure (Y@S Au@CN) exhibited high selectivity of carbon products by suppressing the HER to 26% under visible light irradiation. Further improvement for CO2RR activity was achieved by a surface decoration of the yolk@shell structure with Au25(PET)18 clusters as favorable electron acceptors, resulting in longer charge separation in Au@CN/Auc Y@S structure. Finally, by covering the structure with graphene layers, the designed catalyst maintained high photostability during light illumination and showed high photocatalytic efficiency. The optimized Au@CN/Auc/G Y@S structure displays high photocatalytic CO2RR selectivity of 88%, where the CO and CH4 generations during 8 h are 494 and 198 µmol/gcat., respectively. This approach combining architecture engineering and composition modification provides a new strategy with improved activity and controllable selectivity toward targeting applications in energy conversion catalysis.