Tunable and sustainable photocatalytic activity of photochromic Y-WO 3 under visible light irradiation.

Although photochromic and photocatalytic performance are the most significant features of WO 3 , the effects of photochromism on photocatalytic activities have not been investigated further. Herein, a novel gear-shaped WO 3 , 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 WO 3 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 W 6+ and W 5+ played a key role in separating e - /h + pairs. Importantly, the rapid and reversible conversion between W 6+ and W 5+ could be realized through light radiation or H 2 O 2 treatment. Therefore, the gear-shaped WO 3 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 WO 3 applications for environmental remediation based on photochromic regulation.