Modulation of Charge Trapping by Island-like Single-Atom Cobalt Catalyst for Enhanced Photo-Fenton-Like reaction

Composites-based photocatalysis relies on the interfacial electron transfer between the metallic cocatalyst and photosensitizer (the semiconductor) to realize spatial separation of charge carriers. Herein, an ingenious heterojunction between Co-CN single atom catalysts (SACs) and g-C3N4 is constructed for heterogeneous photo-Fenton-like reactions. Driven by built-in electric field across the heterojunctions, the separation and migration of the photogenerated charge carriers is promoted, leading to the fast electron transfer from the g-C3N4 to the Co-CN SACs. Theoretical calculations and transient absorption spectroscopy reveal the modulated charge transfer and trapping in the SA-Co-CN/g-C3N4 heterostructure, resulting in the remarkably enhanced generation of reactive oxygen species via peroxymonosulfate activation under light irradiation. This ingenious SA-Co-CN/g-C3N4/PMS/vis system is efficient for the oxidation of various antibiotics with high removal efficiency (>98%), a wide operating pH range (pH 3-11) and excellent stability in long-term operation. This study provides a new tactic for rational design of SACs-based heterojunctions to bridge photocatalysis and heterogeneous catalysis, attaining superior photoredox activity via interfacial coupling.