A novel Sn2Nb2O7/defective carbon nitride heterojunction photocatalyst: preparation and application for photocatalytic oxytetracycline removal

Abstract

A traditional type-II Sn₂Nb₂O₇/defective carbon nitride (HCN) heterojunction structure photocatalyst was constructed to enhance the photocatalytic property of the pyrochlore Sn₂Nb₂O₇. Experimental analysis verified that a built-in electric field was formed between Sn₂Nb₂O₇ and HCN, resulting in the photogenerated electrons and holes gathering on the conduction band of HCN and valence band of Sn₂Nb₂O₇, respectively. The formation of Sn₂Nb₂O₇/HCN improved the separation efficiency and transfer rate of photogenerated charge carriers. The optimal photocatalytic oxytetracycline (OTC) removal efficiency of Sn₂Nb₂O₇/HCN was 58.4% after 150 min of visible light irradiation, which was 1.41 and 1.92 times higher than those of Sn₂Nb₂O₇ (41.5%) and HCN (30.4%), respectively. The trapping active species and electron paramagnetic resonance results proved that the dominant active species in the photodegradation of OTC were photogenerated holes, hydroxyl radicals and superoxide anions. This work might provide a new strategy for improving the photocatalytic performance of Sn₂Nb₂O₇ by building traditional type-II heterojunction photocatalysts.