Photo-Driven Iron-Induced Non-Oxidative Coupling of Methane to Ethane

Photo-driven CH₄ conversion to multi-carbon products and H₂ is attractive but challenging, and the development of efficient catalytic systems is critical. Herein, we construct a solar-energy-driven redox cycle for combining CH₄ conversion and H₂ production using iron ions. A photo-driven iron-induced reaction system was developed, which is efficient at selective coupling of CH₄ as well as conversion of benzene and cyclohexane under mild conditions. For CH₄ conversion, 94 % C₂ selectivity and a C₂ H₆ formation rate of 8.4 μmol h^-1 is achieved. Mechanistic studies reveal that CH₄ coupling is induced by hydroxyl radical, which is generated by photo-driven intermolecular charge migration of an Fe³⁺ complex. The delicate coordination structure of the [Fe(H₂ O)₅ OH]²⁺ complex ensures selective C-H bond activation and C-C coupling of CH₄ . The produced Fe²⁺ can be used to reduce the potential for electrolytic H₂ production, and then turns back into Fe³⁺ , forming an energy-saving and sustainable recyclable system.