Uncovering the systematical charge separation effect of boron nitride quantum dots on photocatalytic performance of BiFeO3 perovskite towards degradation of tetracycline antibiotic

Abstract

In this study, metal-free boron nitride quantum dots (BNQDs) were incorporated into the perovskite type BiFeO3 (BFO) structure by facile impregnation technique, which preserved promoted photo-Fenton catalytic activity towards tetracycline hydrochloride (TC-HCl) degradation under visible light irradiation. TEM images represented that BNQDs were uniformly loaded on the perovskite structure as dark dots with the average size of 3 nm, leading formation of BFO@BNQDs heterojunction catalyst. The diffractogram confirmed that the heterojunction sample crystallized well without deviation in the original cubic structure. The optical and photo-electrochemical analyses indicated that modifying perovskite structure with BNQDs significantly facilitated rapid charge transport due to the hole extracting ability of BNQDs yielding enhanced catalytic activity. In photo-Fenton catalytic experiments, 88% of TC-HCl was removed in BFO@BNQDs/1 system while it was 64% for raw BFO and the reaction rate constant of BFO@BNQDs was calculated 1.95 times higher than that of pure BFO. The catalytic activities of as-synthesized catalysts were also examined under different conditions namely solution pH, co-existing anion and water matrix. The high degradation rate (74.5%) was obtained in the sea water suggested a tremendous potential of BFO@BNQDs in practical utilization. The catalytic removal degree of 72% was still achieved at the end of the fourth cycle indicating great durability of heterojunction. After degradation, the mass spectra showed the possible degradation pathway of TC-HCl and the by-products were defined as less toxic after degradation for 120 min. These findings highlight the potential of boron nitride quantum dots in the development of efficient heterojunction photocatalysts.