A novel nano-sized red phosphorus decorated borocarbonitride heterojunction with enhanced photocatalytic performance for tetracycline degradation

Abstract

Removal of antibiotics from aqueous solution by semiconductor photocatalysis has aroused much attention, yet developing high-performance visible-light-driven photocatalysts remains a huge challenge. Herein, red phosphorus/borocarbonitride (RP/BCN) heterojunction photocatalysts were fabricated by growing RP nanoparticles on BCN nanosheets through a vaporization–deposition method. A series of characterization techniques verified the formation of the heterojunction and the improved photo-electric properties. Benefiting from the strong optical absorption and effective photocarrier separation, the RP/BCN composites showed significantly enhanced photocatalytic activity towards tetracycline (TC) degradation. After 90 min of visible light illumination, a TC degradation ratio of 73.8% could be achieved over the optimized photocatalyst with an apparent rate constant of 0.0224 min⁻¹, which was almost 7.5 and 13.2 folds higher than that of pristine RP and BCN, respectively. The possible degradation pathways of TC were illustrated by identifying the reaction intermediates using UPLC-MS analysis. Such improvement was ascribed to the formation of a type-II heterojunction with the intimate interfacial contact between RP and BCN, which greatly facilitated the spatial separation of photoinduced electron–hole pairs. Furthermore, the radical capturing experiments ascertained that the generated holes and superoxide radicals dominated TC degradation. Based on these results, a reasonable mechanism was proposed to depict the photocatalytic degradation of TC over RP/BCN heterojunction composites. This work is expected to pave the way for constructing high-efficiency BCN-based heterojunction photocatalysts towards environmental protection.