A novel BiVO3/SnO2 step S-scheme nano-heterojunction for an enhanced visible light photocatalytic degradation of amaranth dye and hydrogen production

Abstract

The destruction of toxic pollutants and production of hydrogen gas on the surface of semiconductors under light irradiation is the main significance of photocatalysis. Heterojunctions with matching in band gap energy are urgently required for enhancing the redox power of the charge carriers. A step S-scheme BiVO₃/SnO₂ nano-heterojunction was carefully synthesized for a successful photodegradation of amaranth dye and photocatalytic hydrogen evolution. Tetragonal SnO₂ nanoparticles of 80 m² g⁻¹ surface area and distinct mesoporous structure were fabricated by a sol–gel route in the presence of Tween-80 as the pore structure directing agent. BiVO₃ nanoparticles were deposited homogeneously on the SnO₂ surface in an ultrasonic bath of power intensity 300 W. The photocatalytic efficiency in the destruction of amaranth dye soar with increasing BiVO₃ contents of up to 10 wt%. The hydrogen evolution rate reached 8.2 mmol g⁻¹ h⁻¹, which is eight times stronger than that of pristine SnO₂. The sonicated nanocomposites were investigated by XRD, BET, FESEM, HRTEM, EDS, DRS and PL techniques. The step S-scheme heterojunction with superior oxidative and reductive power is the primary key for the exceptional photocatalytic process. The PL of terephthalic acid and the scavenger trapping experiments reveal the charge migration through the step S-scheme mechanism rather than the type (II) heterojunction mechanism.