Tunable and sustainable photocatalytic activity of photochromic Y-WO3 under visible light irradiation

Although photochromic and photocatalytic performance are the most significant features of WO3, the effects of photochromism on photocatalytic activities have not been investigated further. Herein, a novel gear-shaped WO3, with high coloration efficiency, fast reversibility, and remarkable photocatalytic performance was successfully prepared via a facile hydrothermal method. The influence of photochromic effects on its photocatalytic properties was evaluated under visible light irradiation. The results showed that the yellow WO3 sample exhibited higher photocatalytic efficiencies toward tetracycline hydrochloride (TCH), oxytetracycline (OTC), rhodamine B (RhB), and ciprofloxacin (CIP) (94.3%, 87.9%, 76%, and 68.6%, respectively, in 60 min). Further research found that the redox conversion between W6+ and W5+ played a key role in separating e−/h+ pairs. Importantly, the rapid and reversible conversion between W6+ and W5+ could be realized through light radiation or H2O2 treatment. Therefore, the gear-shaped WO3 possessed tunable and sustainable photocatalytic properties and maintained a high level of activity after recycling ten times under visible light irradiation. This work provides new insights into practical WO3 applications for environmental remediation based on photochromic regulation.