A dual S-scheme TiO 2 @In 2 Se 3 @Ag 3 PO 4 heterojunction for efficient photocatalytic CO 2 reduction.

The excellent photoresponse of semiconductors enables them to be promising photocatalysts for CO ₂ reduction, but practical application is hampered by fast recombination of photogenerated carriers, low CO ₂ capture capacity and poor stability. Herein, mesoporous hollow nanospheres of a dual S-scheme titanium dioxide@indium selenide@silver phosphate (TiO ₂ @In ₂ Se ₃ @Ag ₃ PO ₄ ) heterojunction with a large specific surface area are designed and synthesized. The products of photocatalytic CO ₂ reduction are CH ₄ , CH ₃ OH and CO with yields of 3.98, 4.32 and 8.2 μmol g ^-1 h ^-1 , respectively, and the photocatalysts exhibit excellent cycle performance. The excellent photocatalytic performance is attributed to the large specific surface area of the samples and the construction of dual S-scheme heterojunctions. The large specific surface area can provide sufficient active sites for photocatalytic activity. Simultaneously, the built-in electric field (IEF) in the dual S-scheme exposed to light can facilitate the migration of photogenerated electrons from the CB of the oxidation photocatalyst (OP) to the VB of the reduction semiconductor (RP), where they recombine with the photogenerated holes on the VB of the RP, leaving behind photogenerated carriers with high redox ability for photocatalytic activity. This work provides new insights into the mechanism and design of highly efficient heterojunction photocatalysts for CO ₂ reduction.