Local surface plasmon resonance (LSPR)-coupled charge separation over g-C3N4-supported WO3/BiOCl heterojunction for photocatalytic degradation of antibiotics

Efficient photocatalytic degradation of organic pollutants in water heavily depends on the elaborate design of the micro/chemical structure of the catalyst. For g-C3N4, the synergistic incorporation of heterojunction structures is an effective strategy toward enhanced charge separation and broadened response range of light irradiation, rendering improved performances in photocatalysis. Herein, we propose a WO3/BiOCl heterojunction (WB) supported on graphite phase g-C3N4 (CN) nanosheets that simultaneously enables local surface plasmon resonance (LSPR) effect (by WO3) and promotes charge separation at the catalyst interface (by BiOCl). The WO3/BiOCl/g-C3N4 nanocomposites (WB-CN) show high efficiency in the photo-degradation of two model antibiotics, levofloxacin (OFLX) and tetracycline hydrochloride (TC), which are 2.57 and 2.05 times higher than that of unmodified CN, respectively. The Free radical capture experiments confirmed that the significant reactive species are the photo-generated holes and superoxide radicals. Photoluminescence and photoelectrochemical characterizations suggest an LSPR-coupled charge separation mechanism behind the enhanced photocatalytic activity of WB-CN, creating a local Z-scheme heterojunction structure in the composites that improves the separation efficiency of photo-generated carriers. Together, our results highlight the great potential of composite design in developing CN-based photocatalysts for environmental technology.