Enhanced removal of BPA in water: A redistribution of the decisive position of active species due to the interfacial electric field in Fe2O3/TiO2 heterojunction

Ineffective utilization of generated oxidants, such as H 2 O 2 , together with the nonselectivity of •OH, the principal active species, has significantly hindered the growth of discharge plasma in application for wastewater treatment. Herein, the introduction of constructed Fe 2 O 3 /TiO 2 heterojunction to dielectric barrier discharge plasma (DBDP) not only increased oxidant utilization, but also triggered a shift of decisive position of active species from •OH to selective 1 O 2 and O 2 • - towards bisphenol A (BPA) degradation. Experiments and theoretical calculations collectively revealed that the above process was realized under the joint drive of high-energy electrons, photons, and an interfacial electric field in Fe 2 O 3 /TiO 2 heterojunction. Among them, the interfacial electric field facilitated the separation of electron-hole ( e - - h + ) pairs and the transfer of charge to the antibonding orbit for O-O in H 2 O 2 , dissolved O 2 and O 3 absorbed on the metal sites. Such a work offered theoretical guidance for the ongoing growth of discharge plasma at both the macro and micro levels.