Construction of a Z-scheme heterojunction photocatalyst with oxygen vacancies using cobalt–alumina-layered double hydroxide dispersed between bismuth oxybromide layers for efficient photocatalytic reduction of carbon dioxide

Under the context of energy shortages and global warming, the photocatalytic reduction of carbon dioxide (CO2) to carbon monoxide (CO) using simulated sunlight has attracted considerable research attention. Herein, three-dimensional (3D) Z-scheme cobalt–alumina-layered double hydroxide/bismuth oxybromide (CoAl-layered double hydroxide (LDH)/BiOBr) heterojunction photocatalysts with oxygen vacancies were constructed by intercalating two-dimensional CoAl-LDH between BiOBr layers in the mechanical mixing. The conversion of CO2 in the water phase was greatly improved compared to CoAl-LDH/BiOBr under 300-W xenon light. The transformation efficiency of 23.62 μmol⋅g−1⋅h−1 for CoAl-LDH/BiOBr-10 (CBO-10) is 2.96 and 8.34 times that of pure BiOBr and CoAl-LDH, respectively, with CO selectivity in the obtained products reaching as high as 95%. Furthermore, CBO-10 catalysts exhibited outstanding stability in terms of structure and catalytic performance. The construction of Z-scheme heterojunctions and oxygen vacancies enlarges the photoresponse range of the BiOBr catalyst while reducing the photoelectron–hole recombination efficiency. The unique 3D structure offers more Z-scheme heterojunction interfaces for the separation and transfer of electrons between CoAl-LDH and BiOBr during photoreaction. This study is expected to guide the development of new high-performance photocatalysts and the selective regulation of reduction products.