Enhanced photocatalytic degradation of methylene blue through synthesizing of novel of BiVO4/Zn2SnO4 under visible light

Highlights: • The novel BiVO₄/Zn₂SnO₄ binary heterojunction photocatalyst has been first prepared. • The recombination of photogenerated carriers of BiVO₄ was restrained. • A synergistic between BiVO₄ and Zn₂SnO₄ semiconductors is performed. • BiVO₄/Zn₂SnO₄ shows excellent photocatalytic efficiency under simulated solar irradiation. • The photocatalytic enhancement mechanism for degradation MB was discussed. Novel BiVO₄/Zn₂SnO₄ photocatalyst was prepared by two-step hydrothermal method, and the photocatalytic efficiency of the composite was evaluated by methylene blue (MB) degradation. The physicochemical properties of the composite were confirmed by XRD, FT-IR, XPS, SEM, DRS, PL, EIS and transient photocurrent response measurements. Under visible light irradiation, the optimal mass ratio of Zn₂SnO₄ to BiVO₄ was 7wt%, the first-order kinetic constant of MB degradation over BiVO₄/Zn₂SnO₄(7wt%) (0.0473min⁻¹) was 2.2 and 10.3 times of pristine BiVO₄(0.0215min⁻¹) and Zn₂SnO₄(0.0046 min⁻¹), respectively. BiVO₄/Zn₂SnO₄(7wt%) has the best photocatalytic degradation performance for MB with a degradation rate of 99.3% after 80min of reaction. The active species trapping experiments and electron spin-resonance(ESR) spectroscopy confirm that h⁺ and ·O₂⁻ play an important role in photocatalytic degradation, and h⁺ is the main active substance. In addition, the mechanism of photocatalytic system is also discussed.