Photo-thermal cooperation for the conversion of CO2 and CH4 with H2O to C2 oxygenates over SrTiOx supported CuCo

Abstract

Photosynthesis is a potential strategy to enable endergonic process that usually needs high-temperature in thermochemistry to supply the energy for inert-bond activation and/or strong endothermic reaction. The conversion of CO₂ into value-added C₂-oxygenates is a promising process to realize artificial photosynthesis, but suffers from relatively lower efficiency due to complex multi-electron (≥ 10) transfer processes and sluggish kinetics of C–C coupling. This work proposes an all-new H₂O-promoted strategy for efficient production of C₂ oxygenates from the concurrent activation and subsequent co-conversion of CO₂ with CH₄ under photo-thermal cooperation, in which photocatalytic H₂O-splitting derived active hydrogen species for CO₂ activation, and concomitant active oxygen species for CH₄ activation. A formation rate of as high as 2.05 mmol g⁻¹ h⁻¹ for C₂-oxygenates (CH₃CHO and CH₃CH₂OH) in a selectivity of > 86% has been afforded over SrTiO_x supported CuCo under 200 °C and ultraviolet-visible illumination. It has been revealed that SrTiO_x drives photocatalytic H₂O-splitting under the excitation primary from ultraviolet light, paired Cu^I/Cu⁰ sites promote the formation of *CH_xO intermediate from CO₂, Co sites conduct CH₄-to-*CH₃, and C–C coupling of *CH_xO and *CH₃ on adjacent Cu-Co facilitates the generation of C₂-oxygenates.