Rational design of S-scheme carbon-doped graphitic carbon nitride/ZnIn2S4 heterojunction with enhanced photocatalytic performance for Carbendazim

The synergistic combination of elemental doping and heterostructure engineering offers an effective strategy to overcome inherent limitations of conventional graphitic carbon nitride (g-C₃N₄) in photocatalyst application, particularly insufficient active sites, rapid charge carrier recombination, and narrow light absorption. This study introduces carbon self-doping into g-C₃N₄, followed by self-assembly with band-matched ZnIn₂S₄(ZIS) to construct an S-scheme C-g-C₃N₄/ZnIn₂S₄(CCN@ZIS) heterojunction. Multimodal characterization confirms carbon incorporation modifies the band structure of g-C₃N₄, induces n–π* transitions, and creates defect/impurity levels, significantly enhancing light absorption. Crucially, the S-scheme charge transfer mechanism enables efficient separation of photogenerated carriers, substantially boosting photocatalytic performance. These structural optimizations enable the CCN@ZIS-2 composite to achieve 94.3% carbendazim (CBZ) degradation within 60 min—outperforming CCN and ZIS by factors of 1.19 and 1.31, respectively. This work provides novel insights for high-efficiency photocatalytic degradation of pesticide in water environment.