Z‑Scheme\nCdIn₂S₄/Bi₂WO₆ Heterojunction\nfor High Piezo-Photo Synergetic\nPerformance

Abstract

The piezoelectric effect triggered by mechanical energy\ncould establish\nan internal electric field to effectively modulate the separation\nbehavior of carriers. Herein, a novel CdIn₂S₄/Bi₂WO₆ (CIS/BWO) piezo-photocatalyst for removing\ndiclofenac (DCF) from water was constructed for the first time. Encouragingly,\nthe photocatalytic degradation activity of CIS/BWO was effectively\npromoted through the piezoelectric effect. Specifically, 10% CIS/BWO\nexhibited promising DCF degradation performance under co-excitation\nof light irradiation and ultrasonic vibration, with a degradation\nefficiency of 99.9% within 40 min, much higher than that of pure photocatalysts\n(72.3%) and piezocatalysts (60.3%). Meanwhile, an in-depth study of\nthe charge carrier separation mechanism of the CIS/BWO composite under\nthe piezo-photo synergy condition was proposed. Both the built-in\nelectric field induced by the piezoelectric effect in BWO and the\nZ-scheme transfer path of the CIS/BWO heterojunction are beneficial\nto interfacial charge transfer. Moreover, the Z-scheme mechanism was\nfurther demonstrated by trapping experiments and the electron spin\nresonance (ESR) technique. Finally, the corresponding intermediates\nof DCF over CIS/BWO composites and possible degradation pathways were\nalso investigated by DFT calculations and liquid chromatography–mass\nspectrometry.