Single Atomically Anchored Cobalt on Carbon Quantum Dots as Efficient Photocatalysts for Visible Light-Promoted Oxidation Reactions

Generation of efficient light-induced charge separation inside the photocatalyst is an essential factor for a high cata-lytic efficiency. The usual immobilization of metal or metal oxide particles on semiconductor photocatalysts offers an uncontrolled assembly of active sites during the reaction. The introduction of single metal atoms on photocatalysts can lead to extremely high atomic utilization and precise active sites. However, this approach is limited due to the lack of suitable photosensitizers for single atom immobilization. Here, we have designed photocatalytic carbon quan-tum dots with anchoring sites for single cobalt atoms in a defined Co-N4 structure via facile pyrolysis of vitamin B12. Carbon dots functioned as both light-harvesting antenna and support for cobalt atom with high atom loadings up to 3.27 wt.%. This new photocatalytic material demonstrated enhanced visible light absorption, efficient charge separa-tion, and reduced electrochemical impedance, while the single Co atoms acted as th...