Ultra-Fast Construction of Novel S-Scheme CuBi 2 O 4 /CuO Heterojunction for Selectively Photocatalytic CO 2 Conversion to CO.

Herein, step-scheme (S-scheme) CuBi 2 O 4 /CuO (CBO/CuO) composite films were successfully synthesized on glass substrates by the ultra-fast spraying-calcination method. The photocatalytic activities of the obtained materials for CO 2 reduction in the presence of H 2 O vapor were evaluated under visible light irradiation (λ > 400 nm). Benefiting from the construction of S-scheme heterojunction, the CO, CH 4 and O 2 yields of the optimal CBO/CuO composite reached 1599.1, 5.1 and 682.2 μmol/m 2 after irradiation for 9 h, and the selectivity of the CO product was notably enhanced from below 18.5% to above 98.5% compared with those of the bare samples. In the sixth cycling experiment, the yields of main products decreased by less than 15%, and a high CO selectivity was still kept. The enhanced photocatalytic performance of CO 2 reduction was attributed to the efficient separation of photogenerated charge carriers. Based on the photocatalytic activity, band structure and in situ-XPS results, the S-scheme charge transfer mechanism was conformed. The study provides an insight into the design of S-scheme photocatalysts for selective CO 2 conversion.