Constructing oxygen absorption and activation sites in Ce-doped g-C3N4 photocatalyst for effective removal of amoxicillin: Performance, mechanism and degradation pathways

Accelerating oxygen absorption and activation to generate center dot O-2(-) efficiently is challenging toward photocatalytic removal of antibiotic pollutions for water treatment. Herein, the Ce-doped g-C3N4 photocatalysts with active sites for adsorbing and activating oxygen were prepared by a pyrolysis method. It was found that CeCN-1 exhibits excellent performance toward the photocatalytic degradation of amoxicillin (AMX), which was about 3.4 times more than that of pure g-C3N4. Both experimental and theoretical studies elucidated that the Ce-g-C3N4-x have excellent oxygen absorption and activation capacity attributed to the doping of Ce ions destroys the original sp(2) hybrid mode of nitrogen and carbon in the triazine ring, and the increase of solitary electrons forms the activated site. Meanwhile, the generation of N vacancies sites not only accelerate the conversion of excitons to photo-generated carriers but also generate more center dot O-2(-) acting as the main active species for the AMX degradation. Additionally, the photocatalytic degradation pathway of AMX was revealed through HPLC-MS and Fukui index based theorical calculation, proving that the intermediate products degraded by AMX are non-toxic and harm-less. This study disclose the superiority of constructing the O-2 adsorption and activation sites for photocatalytic removal of antibiotic pollutants.