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

Abstract

Singlet oxygen (1O2) is extensively employed in the fields of chemical, biomedical and environmental. However, it is still a challenge to produce high- concentration 1O2 by dioxygen activation. Herein, a system of carbon-supported 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 1O2 production. The catalytic activity trends and mechanisms are revealed experimentally and are also proven by theoretical analyses and calculations. The 1O2 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 ·O2− to enhance 1O2 production. This study offers a universal strategy to enhance 1O2 production in dioxygen activation for future application and reveals the natural essence of basic mechanisms of 1O2 production via rare-earth oxide nanoclusters and rare-earth single atoms.