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 CO₂ 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 CO₂ to oxygenates and hydrocarbons. We shall show the pathway by which CO₂ could be converted to 1-butanol, a C₄ alcohol. Through a series of control experiments and density functional theory (DFT) calculations, we pinpoint that its C₄ backbone was formed from a surface-mediated aldol condensation of acetaldehyde formed from CO₂ reduction, rather through the coupling of four CO intermediates. We also discuss how CO₂ could be reduced to methanol through a tandem process - CO₂ 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 Ti³⁺ and oxygen vacancies (TOV) as the active sites in a vacancy-filling pathway mediated by *H₂COOH. We also give screening rules based on the *HCOOH and *H₂COOH binding energies alongside TOV formation energies. These can facilitate the high-throughput automated design of catalysts for CH₃OH synthesis from tandem CO₂ electrolysis. In the last part of our talk, we show how molecules not commonly observed during CO₂ reduction such as propylene and other C₄-C₆ 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 CO₂ 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.