Enhanced visible-light-driven photocatalytic sterilization of tungsten trioxide by surface-engineering oxygen vacancy and carbon matrix

Abstract

Defect WO3-carbon hybrid nanosheets (D-WO3@C), synthesized by a facile hydrothermal method, is utilized as an effective visible-light driven photocatalyst for sustainable inactivation of bacteria. Detailed characterization through SEM-EDS, XRD, FT-IR, HRTEM, and XPS confirmed the formation of the nanohybrids. As a result, the as-synthesized D-WO3@C exhibited the best sterilization efficiency among all of the WO3 photocatalysts, and 7 log inactivation of E. coli or S. aureus was obtained after treating samples for 45 min with 1000 μg/mL D-WO3@C. It was found that D-WO3@C exhibited enhanced visible-light-driven photocatalytic sterilization in killing bacteria compared with D-WO3 and P-WO3. The results show that the oxygen vacancies and carbon matrix were able to promote photocatalytic performance by triggering a faster interfacial transfer and a higher efficient separation of electron-hole pairs, which most likely is the reason behind the improved bactericidal effect. Furthermore, fluorescent-based cell viability/death tests and SEM technology were employed to demonstrate the lethal effect as well as the integrity of bacterial membranes during photocatalytic process. Photoelectrochemical techniques and UV–visible diffuse reflectance revealed the efficient separation of electron-hole pairs between D-WO3 and carbon matrix. More importantly, after being tested in four cycles, D-WO3@C showed good photocatalytic performance due to its chemical stability. The excellent properties associated with the novel D-WO3/C indicated that they could be considered as a promising light-visible driven photocatalyst to remove, in practice, microbial contamination of water.