Room-temperature coupling of methane with singlet oxygen

Abstract

Owing to emission of methane (CH₄) causing global warming and waste of resources, conversion of CH₄ to value-added chemicals can mitigate environmental sustainability and energy concerns. Direct room-temperature coupling of CH₄ to form ethane (CH₃CH₃) challenges chemists owing to the strong C–H bonds requiring high temperature (>700 °C) for dehydrogenation of CH₄. Oxidative coupling is a promising approach for CH₄ conversion to C₂H₆ using solar energy at room temperature. To achieve high efficiency of C₂H₆ formation, using an appropriate oxidant is a potential strategy to avoid overoxidation during the CH₄ coupling process. Singlet oxygen (¹O₂) has typically manifested a mild redox capacity with a high selectivity to attack organic substrate CH₄. Here, we report a synergistic photocatalytic-oxidative route for direct CH₄ coupling. Under solar light irradiation, a high CH₃CH₃ generation rate of 647 μmol g⁻¹ h⁻¹ is achieved at 25 °C. Our work demonstrates that the solar-oxidative route can result in new and useful C1-based catalytic behaviors.