Sphere-rod-like Ag/AgCl@Fe2O3 Z-scheme heterojunction as photocatalysts for efficient degradation of tetracycline under visible light irradiation

Abstract

Integration of multi-functional components into one is urgent for creating a viable platform to improve photocatalytic efficiency for environmental treatment. Here, MIL-88B–NH2 (Fe) was firstly employed to capture Ag+ cation for the formation of AgCl@MIL-88B–NH2 (Fe), and then turned into the strongly coupled Ag/AgCl@Fe2O3 with sphere-rod-like structure. As prepared Z-scheme Ag/AgCl@Fe2O3 heterojunction exhibited outstanding photocatalytic performance of tetracycline (TC) with a removal efficiency of 94.9% and a reaction kinetics of 0.0272 min−1, superior to single Ag/AgCl or Fe2O3, which attributed to the broad light absorption range and accelerated electron-hole pair separation stemmed from the synergistic effect between surface plasmon resonance effect (SPR) of metal Ag and AgCl/Fe2O3 heterojunction. Meanwhile, Ag/AgCl@Fe2O3 was found to be highly catalytic in the degradation of TC even after consecutive runs. Moreover, active species trapping experiments combined with ESR techniques revealed that superoxide radical, hydroxyl radical, electron, and hole all were involved in photodegradation of TC process. Importantly, the degradation intermediate products of TC were revealed in depth by LC-MS, and a possible degradation pathway was further proposed. This work opens up new insights into the integration of functional composites for the construction of advanced photocatalysts applied in environmental purification.