The mixed marriage of copper and carbon ring-g-C₃N₄ nanosheet: A visible-light-driven heterogeneous Fenton-like catalyst

Effective photogenerated charge separation and rapid Cu(II)/Cu(I) redox cycling is still challenging for photocatalytic reactions and copper-based Fenton-like process, respectively. Herein, a novel heterogeneous Fenton-like catalyst of copper incorporated carbon ring-g-C₃N₄ (Cu-C-CN) was prepared through a facile calcination method. The carbon ring could be intimately connected with g-C₃N₄ via sp²-hybridized C–N bonds to form an in-plane π-conjugated structure. The carbon ring spliced g-C₃N₄ (C-CN) can serve as an effective electron-hole separator owing to the varied electron affinity of two domains (e.g. carbon-ring and g-C₃N₄). The copper species were further introduced to the framework of g-C₃N₄ via the Cu–N bonds to act as acceptors of conduction-electrons from g-C₃N₄ and H₂O₂ activators. Taking the photodegradation of methylene blue (MB) as a model reaction, the decomposition efficiency over Cu-C-CN is 5.5 times higher than that of pristine g-C₃N₄, and would nearly linearly increase with pH. The notable enhancement in photodegradation efficiency could be ascribed to the synergetic collaboration between photocatalysis process and Fenton-like process to generate abundant [rad]OH and e⁻. The Cu-C-CN catalyst shows high recycling stability with negligible Cu leaching due to the strong affinity of Cu²⁺ to g-C₃N₄ framework. The strategy of coupling Fenton-like catalysts, electron-deficient domains (e.g. carbon-ring) into semiconductor-based photocatalysis provides a facile and promising solution to the remediation of water pollution with solar energy.