(Invited) Electrochemical Reduction of Carbon Dioxide to Oxygenates and Hydrocarbons

Abstract

Currently, more than 80% of the world’s energy needs are met by burning fossil fuels. Supplies of these fuels are intrinsically limited and will eventually run out. Combustion of fossil fuels also generates carbon dioxide, whose rapidly increasing atmospheric concentration contributes to global warming. One solution for mitigating atmospheric concentrations of CO 2 is to electrochemically reduce these molecules into chemicals and fuels. If the energy used for these processes is generated from renewable sources such as solar and wind, we can envisage a chemical production cycle that is closed-loop with net zero carbon emission. In this talk, we share our recent works related to the development of catalysts for the selective electroreduction of CO 2 to oxygenates and hydrocarbons. We shall show the pathway by which CO 2 could be converted to 1-butanol, a C 4 alcohol. Through a series of control experiments and density functional theory (DFT) calculations, we pinpoint that its C 4 backbone was formed from a surface-mediated aldol condensation of acetaldehyde formed from CO 2 reduction, rather through the coupling of four CO intermediates. We also discuss how CO 2 could be reduced to methanol through a tandem process - CO 2 was first reduced to formic acid, and the latter can be reduced to methanol using anodized titanium. For the latter step, experiments and DFT calculations identify Ti 3+ and oxygen vacancies (TOV) as the active sites in a vacancy-filling pathway mediated by *H 2 COOH. We also give screening rules based on the *HCOOH and *H 2 COOH binding energies alongside TOV formation energies. These can facilitate the high-throughput automated design of catalysts for CH 3 OH synthesis from tandem CO 2 electrolysis. In the last part of our talk, we show how molecules not commonly observed during CO 2 reduction such as propylene and other C 4 -C 6 products could be formed. References: - W.J. Teh, O. Pique, Q.H. Low, W.H. Zhu, F. Calle-Vallejo and B.S. Yeo. Toward Efficient Tandem Electroreduction of CO 2 to Methanol using Anodized Titanium. ACS Catal . 11, 8467. 2021 . - L.R.L. Ting, Y.J. Peng, B.S. Yeo. Mechanistic Insights into the Selective Electroreduction of Crotonaldehyde to Crotyl Alcohol and 1-Butanol. ChemSusChem . 14, 2963. 2021 . - L.R.L. Ting, R. García-Muelas, A.J.M. Martín, F.L.P. Veenstra, S.T.J. Chen, Y. Peng, E.Y.X. Per, S. Pablo-García, N. López, J. Pérez-Ramírez, and B.S. Yeo. Electrochemical Reduction of Carbon Dioxide to 1-Butanol on Oxide-Derived Copper. Angew. Chemie Int. Ed . 59, 21072. 2020.