Construction of BaTiO3/g-C3N4 heterojunction for promoting atrazine degradation of hydraulic-driven piezocatalytic ozonation

Abstract

Catalytic ozonation, as a popular water purification technology, was restrained with the dilemma of slow Me(n+m)+/Men+ redox cycle of the convention catalysts. To this end, BaTiO3/g-C3N4 (BTO/CN) piezoelectric heterojunction was designed to enhance atrazine (ATZ) degradation in piezocatalytic ozonation, utilizing the overlooked mechanical forces to activate O3 into reactive oxygen species (ROS). Characterization results demonstrated that the couple of BTO and CN successfully formed a Type-II heterojunction, enhancing the separation of piezoelectric carriers (e- and h+). Moreover, BTO/CN showed the better O3 affinity and O3 activation capability over that of BTO and CN. BTO/CN/O3 process achieved 90.1 % ATZ removal, which was 3.5 and 1.7 times over that of the BTO/O3 and CN/O3 processes, respectively. ATZ removal in BTO/CN/O3 process increased with the initial pH value. Cl-, SO42- and NO3- inhibited ATZ removal, but HCO3- enhanced ATZ removal. O3, •OH, O2- and 1O2 were all involved in ATZ degradation and •OH served as the main ROS, accounting for 79.3 % in degrading ATZ. The internal electric field along with the interfacial electric field synergistically boosted the separation and transfer of charge carriers to provide e- for O3 activation and ROS generation. This study broke through the basic need of continuous sacrifice of e- for O3 activation induced by metal redox cycle and provided a novel catalyst design strategy for piezoelectric ozonation.