Engineering the S-scheme heterojunction modulating the charge density of the central carbon atom of half-metallic carbon nitride for boosting CO2 photoreduction

The construction of S-scheme heterojunction can effectively retain higher oxidation and reduction potentials within a compound semiconductor system, exhibiting significant potential in photogenerated carrier separation. Herein, Bi 2 MoO 6 (BMO) nanosheets were grown in - situ on bulk hm-C 4 N 3 (hm-CN) by a one-step hydrothermal method , creating an extremely tight S-scheme heterojunction interface. This interface accelerates the photogenerated electron migration from BMO to hm-CN and inhibits photogenerated electron-hole complexation. DFT calculations confirm that S-scheme heterojunction exhibits the mechanism of charge density modulation for hm-CN, with more electrons enrich on the central C atom. Meanwhile, the energy barrier for photocatalytic CO 2 reduction is reduced from 0.82 eV to 0.59 eV. Consequently, the optimized BMO/CN-150 photocatalyst exhibits the highest performance enhancement in CO 2 photoreduction to CO and CH 4 , which is 14.5 times (CO) and 16.1 times (CH 4 ) of the hm-CN monomer and maintains exception stability over 24 h. This study provides an effective strategy to utilize the charge transfer interaction between heterojunctions to precisely modulate the charge density of a certain component and thus design efficient artificial photosynthesis catalysts. The in - situ growth method is utilized to construct a tight S-scheme heterojunction between hm-C 4 N 3 and Bi 2 MoO 6 for facilitating photogenerated charge separation, and the enrichment of electrons in the central carbon atom of hm-C 4 N 3 lowers the reaction energy barrier. • Bi 2 MoO 6 nanosheets grown in - situ on hm-C 4 N 3 to form a tight S-scheme heterojunction. • Bi 2 MoO 6 /hm-C 4 N 3 S-scheme heterojunction promotes charge separation and inhibits photogenerated carrier recombination. • Photogenerated electrons are enriched at the central carbon atom of hm-C 4 N 3 , lowering the CO generation energy barrier.