Piezoelectric charges elicited a chain reaction of sulfite activation: Performance and mechanism

Taking use of mechanical-to-chemical energy is a promising way to develop sustainable catalysis, but it is hindered by the low reactive oxygen species (ROS) yield induced directly by intrinsic carriers. In this paper, by coupling piezocatalysis with sulfite (S(IV)) activation via a g-C3N4/S(IV)/US ternary system, piezoelectric holes react with S(IV), triggers a chain reaction and brings about a considerable ROS generation for enhancing the degradation of organic pollutants. As a result, profiting from the crucial electron-gaining ability of holes, the kobs of metronidazole removal after adding g-C3N4 increases by 2.02 times from 0.0161 min−1 to 0.0325 min−1. This enhancement occurs because the piezoelectric holes can both promote the transfer of electrons from S(IV) to g-C3N4 and the generation of sulfite radical (SO3−). By this way, the SO3− rapidly reacts with the dissolved oxygen to generate sulfate radical and hydroxyl radical through a chain reaction for water remediation. This study provides a novel strategy to maximize the utilization of piezoelectric holes.