Construction and photocatalytic tetracycline degradation performance of a bismuth vanadate–copper oxide heterojunction

To address the high carrier recombination rate and low degradation efficiency of traditional single-component photocatalysts, this study aims to construct efficient bismuth vanadate–copper oxide (BiVO₄–CuO) heterojunction photocatalysts and investigate their performance in tetracycline degradation.

BiVO₄–CuO heterojunction photocatalysts with different component ratios were prepared via a hydrothermal method and characterized using various analytical techniques to analyze their structural properties. The photocatalytic performance was evaluated using tetracycline as the target pollutant under visible light irradiation (λ > 420 nm). The degradation mechanism was elucidated through kinetic analysis, active species trapping experiments, and electrochemical measurements. The effects of reaction temperature, pH, catalyst dosage, and initial tetracycline concentration on degradation efficiency were systematically investigated.

The experimental results showed that 1) X-ray diffraction and high-resolution transmission electron microscopy confirmed the successful construction of a heterojunction structure with intimate contact between BiVO₄(121) and CuO(-111) facets; 2) under optimal conditions (catalyst dosage of 0.5 g/L; tetracycline concentration of 20 mg/L; pH 7.0), the BC-1 sample achieved an apparent rate constant of 0.0216 min^-1, with 90.3% degradation and 85.6% mineralization rates within 120 min; 3) Mott–Schottky and X-ray photoelectron spectroscopy analyses verified the formation of a Z-scheme band structure favorable for carrier migration, extending the carrier lifetime to 15.6 ns; 4) electron spin resonance and electrochemical tests revealed · and ·OH as the primary active species, achieving degradation through C—N and amide bond cleavage; 5) after five cycles, the catalyst maintained 91.8% of its initial activity.

Through facet control and interface engineering, an efficient BiVO₄–CuO heterojunction photocatalyst was successfully constructed. The Z-scheme band structure significantly enhanced the separation efficiency of photogenerated carriers, achieving effective degradation and mineralization of tetracycline. This work provides valuable insights for the development of high-performance composite photocatalytic materials.