An Investigation of Surface-Functionalized Electrocatalysts for Efficient CO2 Reduction to Multi-Carbon Products

Despite rapid progress in the past few years, efficiently reducing CO₂ to valuable multi-carbon products, such as ethanol and ethylene, remains a formidable challenge.^[1] Overcoming the mechanistic hurdles in the path toward these compounds requires investigating new concepts in catalyst design while gaining fundamental insights into their mechanistic effect.

Several examples from (non-electrochemical) heterogeneous catalysis illustrate how adsorbed organic ligands can be used to tune activity and selectivity due to the emergence of electronic and geometric effects,^[2] but this powerful strategy of using surface modifiers remains relatively unexplored in the context of CO₂ reduction.^[3] Nevertheless, recent reports provide compelling evidence of its potential: for instance, Buonsanti et al. showed the promoting effect on CO evolution of imidazolium-based ligands anchored to the surface of silver nanoparticles,^[4] and a recent publication by Sargent et al. demonstrated how N-aryl-pyridinium-functionalized copper electrodes attain high Faradaic efficiency for CO₂ reduction to ethylene at elevated current densities.^[5]

In this contribution, we show how the adsorption of sub-monolayer coverages of small organic ligands influences the eCO₂RR selectivity patterns of well-defined metallic surfaces. In tandem with the characterization of the functionalized surfaces by x-ray photoelectron and infrared spectroscopies, these findings provide unique insights into the impact of adsorbed organic molecules on CO₂ reduction, informing the development of a new strategy with the potential to achieve breakthrough advances toward the production of multi-carbon compounds.

[1] S. Nitopi, E. Bertheussen, S.B. Scott et al., Chem. Rev. 2019, 119, 7610-7672

[2] M.A. Ortuño, N. López, Catal. Sci. Technol. 2019, 9, 5173-5185

[3] Y. Fang, J.C. Flake, J. Am. Chem. Soc. 2017, 139, 3399-3405

[4] J.R. Pankhurst, Y.T. Guntern, M. Mensi, R. Buonsanti, Chem. Sci. 2019, 10, 10356-10365

[5] F. Li, A. Thevenon, A. Rosas-Hernández et al., Nature 2019, 577, 509-513