WC/BiOCl binary composite photocatalyst for accelerating interfacial charge separation and sulfamethoxazole degradation

Highlights: • A novel WC/BiOCl binary composite photocatalyst was synthesized. • Intimate interface contact has internal electrical field from WC to BiOCl. • The introduction of WC enhanced light absorption and electron transportation. • A possible photodegradation pathway of sulfamethoxazole was proposed. A novel n-n type WC/BiOCl binary photocatalyst was synthesized, and applied to sulfamethoxazole (SMX) degradation. The physical and photoelectric properties of the WC/BiOCl were characterized by various experimental and calculational methods. An intimate interfacial contact between WC and BiOCl was identified, which help to reduce the aggregation of BiOCl and more importantly, build an internal electrical field between WC and BiOCl. It is interesting to find that the WC layer(s) can help to reduce the interfacial charge transfer resistance and act as electron transfer and storage sites. Subsequently, the holes are engaged in the oxidation of SMX by WC/BiOCl. Additionally, WC/BiOCl photocatalyst has more reactive sites and absorbs more incident photons compared with pure BiOCl. Quenching and electron spin resonance (ESR) experiments indicate that O₂^·- is the main active species, holes and OH^• are also involved. The degradation pathway of SMX and the enhancing mechanism for the photodegradation through the combination of WC and BiOCl were explored. This work provides a novel binary photocatalyst for SMX degradation.