Fabrication of MoSe2/Bi3O4Br Z-scheme heterojunction with enhanced photocatalytic performance

Exploring a Z-scheme heterojunction photocatalyst with efficient charge separation and outstanding redox ability is necessary but very challenging. MoSe2 has received much attention as a co-catalyst due to its excellent optical properties. Herein, First-principles density functional theory (DFT) was employed for theoretical calculations of the energy band structure of Bi3O4Br, revealing crossed energy band structures with MoSe2, indicating favorable conditions for heterojunction formation. A solvothermal method was then used to synthesize MoSe2/Bi3O4Br heterostructure photocatalysts with a 2D/2D layered configuration. Characterization via SEM, TEM, DRS, XPS, BET, EIS, and PL confirmed that the MoSe2/Bi3O4Br heterostructure exhibited a larger specific surface area, more active sites, lower impedance, and reduced carrier recombination rate compared to pure Bi3O4Br and MoSe2. These features are advantageous for photocatalytic reactions. The optimized 2.5% MoSe2/Bi3O4Br photocatalyst demonstrated superior performance, achieving nearly 100% photodegradation of RhB under 90 minutes of simulated sunlight, with an apparent rate constant k value 7.57 times higher than that of Bi3O4Br. The composite photocatalyst exhibited excellent cycling stability over five experiments without significant reactivity attenuation. Finally, a plausible Z-scheme photocatalytic mechanism for MoSe2/Bi3O4Br heterojunctions is proposed based on experimental findings. This study provides new insights for exploring the construction of wide-band semiconductor heterojunctions.