Enhancing singlet oxygen production of dioxygen activation on the carbon-supported rare-earth oxide nanocluster and rare-earth single atom catalyst to remove antibiotics

Singlet oxygen (O-1(2)) is extensively employed in the fields of chemical, biomedical and environmental. However, it is still a challenge to produce high- concentration O-1(2) by dioxygen activation. Herein, a system of carbonsupported rare-earth oxide nanocluster and single atom catalysts (named as RE2O3/RE-C, RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y) with similar morphology, structure, and physicochemical characteristic are constructed to activate dissolved oxygen (DO) to enhance O-1(2) production. The catalytic activity trends and mechanisms are revealed experimentally and are also proven by theoretical analyses and calculations. The O-1(2) generation activity trend is Gd2O3/Gd-C>Er2O3/Er-C>Sm2O3/Sm-C>pristine carbon (C). More than 95.0% of common antibiotics (ciprofloxacin, ofloxacin, norfloxacin and carbamazepine) can be removed in 60 min by Gd2O3/Gd-C. Density functional theory calculations indicate that Gd2O3 nanoclusters and Gd single atoms exhibit the moderate adsorption energy of center dot O-2 to enhance O-1(2) production. This study offers a universal strategy to enhance O-1(2) production in dioxygen activation for future application and reveals the natural essence of basic mechanisms of O-1(2) production via rare-earth oxide nanoclusters and rare-earth single atoms.