PPh₃ enhanced catalytic conversion of CO₂ to ethanol over a Ru-Co catalyst

CO₂ is a major greenhouse gas as well as an abundant, cheap, and renewable carbon resource. Synthesis of ethanol from CO₂ using a homogeneous catalyst represents a promising protocol for CO₂ utilization, yet achieving high catalytic performance with a cost-effective catalyst remains a challenge. Herein, we report a highly efficient Ru-Co-PPh₃ bimetallic catalyst for ethanol synthesis using CO_2, methanol, and H₂. The ethanol space time yield (STY) reached as high as 4.4 g L^-1 h^-1, with a turnover frequency (TOF) of 23.2 h^-1 and an ethanol selectivity of 85.6 C-mol% in total products, outperforming the previous reports of homogeneous catalytic systems for conversion of CO₂ to ethanol. The PPh₃ ligand enabled the high-efficiency reaction by direct utilization of much cheaper Ru-Co precursors and with lower catalyst dosage. Notably, the PPh₃ ligand played multiple roles in improving the activity, selectivity and stability of the catalyst. The reaction mechanism was also discussed based on a series of control experiments. This work provides a sustainable and practical way of ethanol synthesis using CO₂ as a feedstock.