Band shifting triggered ·OH evolution and charge separation enhanced H2O2 generation in piezo-photocatalysis of Silleń-Aurivillius-structured Bi4W0.5Ti0.5O8Cl

Abstract

Photocatalytic oxygen activation shares a broad prospect as it reveals a giant potential in advanced oxidation and H2O2 production. This work demonstrated the efficient oxygen activation via ultrasonic/visible-light triggered piezo-photocatalysis of Bi4W0.5Ti0.5O8Cl, a novel Silleń-Aurivillius-structured piezoelectric material with a wide light-absorption range. The material possessed a superior oxygen activation performance in piezo-photocatalysis that far exceeded that in the individual photocatalysis or piezocatalysis. In situ electrochemical and fluorescence measurements were introduced to analyze the mechanism of the enhanced catalytic activity systematically. Due to the downward band shifting and anisotropic migration caused by ultrasonic induced piezo-potential, not only the oxygen reduction reaction (ORR) process in oxygen activation was kinetically facilitated, but also the VB potential of Bi4W0.5Ti0.5O8Cl was positive enough so that the water oxidation and ·OH generation reaction were thermodynamically favorable. With the boosted effect from multiple aspects, the maximum yield of H2O2 reached 530.4 μmol·h−1·g−1 by Bi4W0.5Ti0.5O8Cl catalyst without metal-deposition in non-sacrificial system. Our work illustrated the effect of charge modulation on oxygen activation in Silleń-Aurivillius-structured Bi4W0.5Ti0.5O8Cl, and delivered insight into the mechanism of piezo-enhanced photocatalytic H2O2 generation.