Manipulating Singlet Oxygen Generation on Co Nanoclusters-Confined g-C3N4 Macroscopic Beads for Boosted Water Decontamination

Abstract

Reducing the migration distance of reactive oxygen species (ROS) and enhancing interfacial electron transfer represent effective approaches for enhancing the reactivity of heterogeneous catalysts, albeit still posing significant challenges. Herein, we successfully synthesized ultrasmall cobalt nanoclusters-confined g-C3N4 macroscopic beads with N-doped carbon dots (Co/NC@CN beads). Compared to unconfined Co/C and Co/C@CN beads, Co/NC@CN beads demonstrated remarkable utilization efficiency of PMS (84.3%), achieving complete degradation of TC within 20min at a rate of 162.1min-1·M-1, surpassing most reported catalysts. Besides, Co/NC@CN beads predominantly generated singlet oxygen (1O2), ensuring efficient removal of micropollutants with resistance to pH and complex water bodies. Experiments have proven that the strong interaction between Co clusters and g-C3N4 beads containing NC dots facilitated the generation of interfacial electron transfer by optimizing the electronic structure of Co nanoclusters, thereby Co/NC@CN beads could capture electrons from tetracycline (TC) and PMS molecules towards dissolved oxygen (DO) to form O2·-, which subsequently converted into 1O2. More importantly, the efficiency of the flow-through unit in the continuous degradation of TC with zero discharge was substantiated by long-term experiments, and its performance could be restored through a straightforward low-temperature carbonization process. This study offers a universal design framework for the creation of various confined macroscopic beads, enabling the achievement of highly effective wastewater treatment.