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.