(Invited) Effect of Nanostructure and Surface Chemistry on Activity and Selectivity of Cu-Based Electrocatalysts for Carbon Dioxide Reduction

Electrochemical conversion of carbon dioxide (CO2) to value-added chemicals using electricity from renewable sources represents a promising path to carbon-neutral fuel cycle and enhanced economic benefits.1 To date, copper (Cu) has been the leading metal electrocatalyst for the electroreduction of CO2 to high-value chemicals: fuels and chemical feedstocks. Although there has been a significant progress in CO2 reduction reaction (CO2RR), the overall CO2RR performance of Cu-based electrocatalysts is still limited by poor selectivity, resulting in a variety of products, such as hydrogen, carbon monoxide, formic acid, methane, and ethylene.2 Enhancing the CO2RR rate relative to the competing hydrogen evolution reaction (HER) and achieving high selectivity for multi-carbon products thus represent the major scientific challenges. In this presentation, we will summarize our study of innovative Cu-based catalysts aimed at producing high energy-density chemicals, enhancing the understanding of reaction mechanism, and bringing CO2RR closer to practical application. The study has focused on the relationship between the composition and structure of Cu-based electrocatalysts, especially the nanostructure and oxidation states (Cu0, Cu+, and Cu2+), on CO2RR activity. By using a novel approach in the catalyst synthesis we have been able to obtain Cu-based materials with controlled nanostructure, e.g., pore-size distribution, higher surface area, and correlate the catalyst morphology with the selectivity for multi-carbon products. We have associated the formation of CO2RR products with the presence of different active sites on the catalyst surface, a necessary step towards achieving desirable selectivity. We will also recap the results of a study on the effect of adding a secondary transition metal, e.g., Zn, Ni, and Ag, on electrocatalytic properties of Cu-based catalysts. The rationale behind this approach has been to tune electrocatalytic activity and selectivity via changing the binding strength of the key intermediates, such as *OCHO, *CO, *COOH, *CHO, and *COH. References G. Kibria, J. P. Edwards, C. M. Gabardo, C.-T. Dinh, A. Seifitokaldani, D. Sinton, and E. H. Sargent, Adv. Mater. 2019, 31, 1807166. S. Nitopi, E. Bertheussen, S. B. Scott, X. Liu, A. K. Engstfeld, S. Horch, B. Seger, I. E. L. Stephens, K. Chan, C. Hahn, J. K. Nørskov, T. F. Jaramillo, and I. Chorkendorff, Chem. Rev. 2019, 119, 7610−7672.