Synergistic effect of oxygen vacancies and surface electric field: Boosting visible-light photocatalytic degradation of tetracycline over Bi2WO6

Tetracycline (TC) pollution in water bodies has posed a persistent threat to ecological security and human health. Pure bismuth tungstate (BWO) suffers from low carrier separation efficiency, narrow light response range, and insufficient active sites in water pollutant treatment, which severely restricts its photocatalytic application. This work proposes a novel dual-synergistic strategy of oxygen vacancy defects and tourmaline spontaneous surface electric field, and constructs tourmaline/oxygen vacancy-rich Bi 2 WO 6 (T/OvBWO) Schottky heterojunctions via a one-step ethylene glycol solvothermal method. The as-prepared T/3OvBWO features a hierarchical nanoparticles-on-rod structure, retains the pristine crystal structure of BWO without inducing impurity phases after the introduction of oxygen vacancies and tourmaline, and exhibits enhanced visible-light absorption and surface area relative to BWO. Under visible-light irradiation, the optimized 40 % T/3OvBWO achieves a TC removal efficiency of 88.2 % within 60 min, with an apparent with apparent rate constants 2.5 and 2.6 times those of pure BWO and T, respectively. The synergistic effect of oxygen vacancies and tourmaline surface electric field significantly accelerates charge separation and suppresses carrier recombination. Meanwhile, the catalyst exhibits strong adaptability in a pH range of 3–11, and remains over 80 % TC removal efficiency after 4 cycles with no obvious structural damage or ion leaching. This work provides a green, low-cost strategy for constructing high-performance BWO-based photocatalysts, which exhibits promising application potential in antibiotic wastewater treatment.