Strong evidence for interface-field-induced photocarrier separation in new AgFeO2-BiVO4 heterostructures and their efficient photo-Fenton degradation of ciprofoxacin

Abstract

Deep elucidation of photocarrier transfer and separation mechanism is scientifically significant for developing new photocatalysts in pollutant elimination. In this study, we have immobilized AgFeO2 (AFO) nanoparticles on the surface of BiVO4 (BVO) nanobricks to construct new BVO-AFO heterostructured photocatalysts. Multiple advanced characterization techniques combined with theoretical calculations corroborate substantial evidence for the formation of built-in electric field at the BVO-AFO heterojunction interface and efficient photocarrier transfer/separation behavior and mechanism. Simulated-sunlight-driven photodegradation of ciprofoxacin (CIP) demonstrates an important enhanced photocatalysis of the heterostructure photocatalysts; particularly, the BVO-15 %AFO exhibits a photodegradation performance with η(30 min) = 89.9 % and kapp = 0.06659 min−1, which is enhanced by 4.2 (or 3.4) times over that of bare BVO (or AFO). The heterostructure-enhanced photocatalysis is benefited from the interface-field-facilitated transfer and separation of photocarriers, thus extending their lifetime and making them more probable to participate in the photocatalytic reactions. Furthermore, the BVO-AFO heterostructured photocatalysts demonstrate an important activation of peroxymonosulfate (PMS) or H2O2 to generate additional •OH and •SO4− reactive species, thus further promoting the CIP degradation. This work provides an important scientific basis for designing excellent heterostructured photocatalysts.