Visible-light-driven photocatalytic inactivation of Escherichia coli by 0D/2D CeO2/g-C3N4 heterojunction: bactericidal performance and mechanism

Photocatalytic inactivation has been considered as a promising strategy to address the biohazards threat to human health. However, acquiring an efficient photocatalytic system with the merits of visible-light response is still challenging. In this study, a novel visible-light-driven 0D/2D CeO2/g-C3N4 heterojunction photocatalyst was fabricated and the photocatalytic bactericidal performance of CeO2/C3N4 composites were evaluated by using Escherichia coli K-12 (E. coli K-12). The results showed that 7 log cfu/mL Escherichia coli was completely inactivated by the optimal 8% CeO2/g-C3N4 composites within 3 h visible-light irradiation, but only 0.4 and 1.4 log cfu/mL Escherichia coli were inactivated by CeO2 and g-C3N4, respectively. This finding indicated that the CeO2/g-C3N4 composite has outstanding photocatalytic bactericidal performance over the bare CeO2 or g-C3N4, which should be attributed to the effective separation and migration of photoinduced electron-hole pair. In addition, the result of trapping experiments indicated that the major active species of E. coli K-12 inactivation are photoinduced hole and superoxide radicals. Furthermore, the Z-scheme charge migration mechanism was proposed for the photocatalytic bactericidal process of CeO2/g-C3N4 basing on the bactericidal performance and redox potential of the catalysts. This work confirmed that the constructing of the CeO2/g-C3N4 heterojunction is anticipated to be an effective strategy for water disinfection under visible-light illumination in a sustainable manner.