Atomically Dispersed Cobalt on Carbon Notride For Peroxymonosulfate Activation: Switchable Catalysis Enabled by Visible Light Irradiation

Abstract

Herein, we present atomically dispersed cobalt anchored carbon nitride as a flexible photoswitch to regulate peroxymonosulfate (PMS) activation pathways. Under dark environment, the PMS activation undergoes a nonradical pathway with unique high-valent cobalt-oxo [Co(IV)] species as primary oxidants. Hydroxyl radical triggered by Co(IV) serves as secondary intermediate oxidant. Strikingly, it is interesting to find that such Co(IV)-based nonradical pathway can be switched to a radical-dominated pathway under visible light irradiation. On the basis of experiment and DFT calculations, the switchable catalysis can be attributed to the formation of photoinduced hole-trapping sites on the single Co atoms, which result in the primary PMS activation sites convert from single Co atoms to melem units. Considering the distinctive oxidation feature of Co(IV) and radical species, our finding provides a novel strategy to expand the application possibilities of Co-based Fenton-like process in dealing with different environmental issues by flexibly controlling the PMS catalytic pathways.

Keywords: single cobalt atom catalyst, peroxymonosulfate, high-valence cobalt-oxo species, radical oxidation, switchable catalysis