Flexoelectricity-induced enhancement in carrier separation and photocatalytic activity of a photocatalyst

In this paper, we have elucidated the role of flexoelectricity in the photoexcited carrier separation and photocatalysis enhancement by comparatively investigating the photocatalytic, flexocatalytic and flexo-photocatalytic activities of centrosymmetric Ag2MoO4 photo-catalyst for degrading methylene blue (MB). Ultrasonic vibration was used to induce the flexoelectric effect in Ag2MoO4, and the flexo-photocatalytic experiment was performed by simultaneously irradiating the reaction solution with simulated sunlight and ultrasonic wave. It is demonstrated that the photo-flexocatalysis of Ag2MoO4 is much higher than its single photocatalysis and flexocatalysis, implying an obvious flexoelectricity-enhanced mechanism of photocatalysis. To incorporate the photo-flexocatalysis of Ag2MoO4 into practical application in environmental purification, the effects of initial MB concentration, catalyst dosage, pH and various anions on the flexo-photocatalytic degradation of MB over Ag2MoO4 were investigated. Flexo-photocatalytic degradation of methyl orange (MO)/rhodamine B (RhB)/MB mixture dyes and other organic pollutants including tetracycline hydrochloride (TC) and ciprofloxacin (CIP) were also investigated, further confirming the excellent flexo-photocatalytic performance of Ag2MoO4.