Synergistic enhancement of Ce–ZnO/g-C3N4 photocatalytic performance using N,O-bis-vacancy induction and S-scheme heterojunctions

Abstract

The photocatalytic decontamination of organic pollutants is an environmentally friendly and efficient water treatment method. The introduction of vacancies, heterojunctions, and doping can enhance the performance of photocatalysts for such applications. In this study, N,O double-vacancy Ce–ZnO/g-C3N4 S-scheme heterojunction photocatalysts were prepared. It is found that the electron separation and transfer efficiencies are considerably improved by the presence of nitrogen vacancies in graphitic carbon nitride (g-C3N4) and oxygen vacancies in ZnO, in addition to the S-scheme heterojunction created between the two materials. In the degradation of methylene blue and ciprofloxacin, the degradation rates exhibited by Ce–ZnO/g-C3N4 are significantly higher than those of the g-C3N4/ZnO system. This remarkable photocatalytic performance of Ce–ZnO/g-C3N4 may result from three key factors: (i) Ce doping, which produces impurity energy levels; (ii) the generation of electron capture centres by the N and O vacancies; and (iii) the synergistic effect of the S-type heterojunction formed at the interface between the two materials. This study therefore provides new approaches for the use of doping, vacancies, and heterojunctions to induce the efficient degradation of organic pollutants.