Synthesis of an efficient, and recyclable mesoporous BiVO4/TiO2 direct Z-scheme heterojunction by sonochemical route for photocatalytic hydrogen production and photodegradation of rhodamine B dye in the visible region

Sonicated mesoporous BiVO4/TiO2 heterojunctions were recorded for highly efficient photodegradation of rhodamine B dye and production of hydrogen gas. The heterojunction structures were characterized by XRD, DRS, FTIR, BET, FESEM, HRTEM and PL. The efficiency of the radiation power of ultrasound waves [50-300 Watt/cm2] on dye degradation and efficiency of hydrogen production was established. BiVO4 shifts the photocatalytic response of titania toward visible region. The photocatalytic efficiency of RhB removal on the nanocomposites surface containing 10 wt% BiVO4 is 0.021 min-1 tenfold higher than that of bare TiO2 (0.0023 min-1). The optimum concentration of BiVO4 was found to be 10 wt% that generate hydrogen gas with rate equal to 14.3 mmolg- 1h- 1. Ultrasound radiation is a prime key in reducing the population of particle aggregates and reflects a strong interaction between BiVO4 and TiO2 nanoparticles that results in lowering the electron-hole pairs recombination rate and increase the concentration of active sites and amount hydrogen evolved. The production of hydroxyl and superoxide radicals suggest a direct Z-scheme mechanism for explaining the high photocatalytic reactivity of sample.