Abiotic Synthesis with the C-C Bond Formation in Ethanol from CO2 over (Cu,M)(O,S) Catalysts with M = Ni, Sn, and Co

Abstract

We demonstrate copper-based (Cu,M)(O,S) oxysulfide catalysts with M = Ni, Sn, and Co for the abiotic chemical synthesis of ethanol (EtOH) with the C-C bond formation by passing carbon dioxide (CO₂) through an aqueous dispersion bath at ambient environment. (Cu,Ni)(O,S) with 12.1% anion vacancies had the best EtOH yield, followed by (Cu,Sn)(O,S) and (Cu,Co)(O,S). The ethanol yield with 0.2 g (Cu,Ni)(O,S) catalyst over a span of 20 h achieved 5.2 mg. The ethanol yield is inversely proportional to the amount of anion vacancy. The kinetic mechanism for converting the dissolved CO₂ into the C₂ oxygenate is proposed. Molecular interaction, pinning, and bond weakening with anion vacancy of highly strained catalyst, the electron hopping at Cu⁺/Cu²⁺ sites, and the reaction orientation of hydrocarbon intermediates are the three critical issues in order to make the ambient chemical conversion of inorganic CO₂ to organic EtOH with the C-C bond formation in water realized. On the other hand, Cu(O,S) with the highest amount of 22.7% anion vacancies did not produce ethanol due to its strain energy relaxation opposing to the pinning and weakening of O-H and C-O bonds.