Nanoengineering construction of g-C₃N₄/Bi₂WO₆ S-scheme heterojunctions for cooperative enhanced photocatalytic CO₂ reduction and pollutant degradation

S-scheme heterojunction photocatalysts featuring efficient charge transport paths provide a promising strategy for cooperative achieving photocatalytic CO₂ reduction reaction (CO₂RR) and Rhodamine B (RhB) degradation. In this work, S-scheme heterojunctions composed of g-C₃N₄ nanosheets coated on Bi₂WO₆ nanosheets were prepared by a one-step hydrothermal method, resulting in broad-spectrum light absorption, high electron–hole separation efficiency, and excellent photocatalytic CO₂ reduction and RhB oxidization performance. Mechanistic analysis revealed the formation of a directional charge transport path at the interface of the heterojunction, which maintained a high oxidation and reduction potential and improved the efficiency of photoexcited carrier separation. In particular, the synergistic reaction system showed excellent photoredox activity compared with the two separate half-reactions. The optimal catalyst 15CN/BWO displayed the highest CO₂ conversion efficiency, with CO and CH₄ generation rates of 4.3 and 2.7 μmol g⁻¹h⁻¹, respectively, and the degradation efficiency of the composite heterojunction was significantly higher than that of its constituent materials. This work provides a new possibility for designing a novel dual-function photocatalytic reaction system.