Synergistic enhancement of TiO2 photocatalysis via Bi deposited BiVO4 and narrow-bandgap CuS co-modification: Experiment and DFT study

This study demonstrates an innovative Z-scheme heterojunction photocatalyst through the rational design of CuS/Bi-BiVO 4 /TiO 2 composite films for efficient heavy metal ion removal. The composite was fabricated via hydrothermal synthesis and systematically evaluated through photoelectrochemical measurements and DFT calculations. Results demonstrated a redshifted absorption peak (380 nm to 600 nm), a reduced bandgap (2.86 eV to 2.11 eV), and improved charge transfer, possessing 91.4 % Cr(VI) reduction efficiency under simulated sunlight, which is 5.1 times higher than that of pure TiO 2 . After multiple cycles, it maintains a stability of 80 %. The low work function of CuS calculated by DFT simulations and EPR radical capture experiments confirmed the formation of Z-scheme heterojunctions. In summary, the ternary system synergistically optimized the photoelectric properties, charge separation and redox activity of TiO 2 . This work provides a scalable strategy for TiO 2 -based photocatalysts in water purification and advances mechanistic insights for designing multicomponent environmental materials. • CuS/Bi-BiVO 4 /TiO 2 film was synthesized by hydrothermal method. • The film has 91.4 % Cr(VI) reduction, 82.08° contact angle, 80 % cycling stability. • DFT confirms low work function of CuS facilitates electron transfer in heterojunction. • This work provides a strategy for multi-component photocatalyst design in environmental remediation.