Performance and mechanism study on the degradation of RhB by I-g-C3N4@MoO3 heterojunction

A series of S-scheme heterojunctions, XCN@MoO 3 (XCN@M, X = Cl, Br, I), were synthesized via a simple thermal polymerization, and the effect of halogen doping on construction of S-scheme heterojunctions was systematically explored. The ICN@M heterojunction showed exceptional photocatalytic performance, achieving 100 % degradation of 50 mg/L RhB in 90 min, 40.37 times and 2.34 times higher than pure g-C 3 N 4 and CN@M, respectively. Notably, ICN@M outperformed CN@M and some other photocatalysts reported. DFT result revealed halogen doping reduced the work function of CN, proved the maximum work function difference of ICN@M and the formation of the strongest built-in electric field between the surface of MoO 3 with an electron-rich region and the surface of ICN with a hole-rich region, thus facilitating electron transfer at the heterojunction interface, reducing recombination of photogenerated carriers and promoting the catalytic performance. Fukui function and frontier orbital theory identified a possible degradation pathway of RhB dominated by ∙O 2 – and 1 O 2 and the toxicity of final products during the photocatalysis degradation of RhB was evaluated. This work highlighted the importance of work function differences in designing photocatalyst heterostructures and offered a new option for environmental treatment.