Highly exposed active sites of Au nanoclusters for photocatalytic CO2 reduction

The selectivity and activity of photocatalytic CO2 reduction can be effectively enhanced by modulating the reduction pathway of CO2 molecules and promoting the separation of photogenerated charges. Here, we synthesized an Au nanoclusters (Au NCs) modified BiOBr nanosheets catalyst with highly exposed Au active sites by liquid nitrogen assisted ionothermal method. Compared with the pristine BiOBr, the 2.0 wt% Au25 NCs/BiOBr showed excellent photocatalytic activity with a nearly double increase in the rate of CO emission (43.57 μmol g−1h−1). Through relevant experimental characterizations and density functional theory (DFT) calculations, it had been proved that the increased CO2 reduction activities of the samples are attributed to the Au active sites. The increase of Au active sites lowered the CO2 thermodynamic reaction energy barrier and also changed the reaction pathways. This work will play a positive role in application of Au NCs catalysts in photocatalytic applications in the further.