Acceleration of Singlet Oxygen Evolution by Sonopiezoelectric Charge Transfer Over SrTiO3-TiO2 Heterojunction for Selective Oxidation

Sonopiezo-mediated heterogeneous catalysis is a promising technology for efficient removal of organic pollutants from wastewater. Nevertheless, it is challenging in real water matrix with coexisting ions due to the rather-limited selectivity of reactive oxygen species if any. Herein, a sonopiezo-triggered singlet oxygen evolution system for selective removal of tetracycline hydrochloride (TCH) was rationally designed by SrTiO 3 -TiO 2 heterojunction with a TiO 2 -terminated SrTiO 3 S-scheme interfacial structure. SrTiO 3 -TiO 2 heterojunction exhibits a dramatically expanded piezoelectric constant ( d 33 ), which produces a synergistic effect on improving the separation and transfer efficiency of charge carrier for efficient TCH degradation. Moreover, SrTiO 3 -TiO 2 heterojunction presents a high sonopiezo-current, which attractively indicates that SrTiO 3 -TiO 2 heterojunction has a potential capacity of charge separation under sonopiezo initiation. Remarkably, the mechanism was identified as the continuous generating of singlet oxygen ( 1 O 2 ), in which the sonopiezo-generated electrons trigger the formation of superoxide anion radical (•O 2 − ) and its subsequent transformation to generate 1 O 2 by expending more sonopiezo-generated holes. These findings provided new insights towards developing nonradical system for effective and selective oxidation of electron-rich pollutants via sonopiezo-catalytic process.