Speakers
Description
Electrocatalytic conversion of CO$_2$ to higher order hydrocarbons has been proposed as one of the tools available to help mitigate the effects of anthropogenic climate change and create a carbon-neutral energy cycle.$^1$ The only pure metal that is capable of reducing CO$_2$ to C$_{2+}$ hydrocarbons is copper (Cu). However, it suffers from low selectivity towards these products.$^2$ Recent work in the literature has achieved high yields for C$_{2+}$ products at reasonable current densities$^{3–5}$, but a fundamental understanding of the nature of the catalytic active sites still remains elusive. Pristine, atomically flat ultra-high vacuum (UHV)-prepared Cu single crystal surfaces function as model catalysts and enable a better connection between experimental work and theoretical calculations. These surfaces were instrumental in work showing that atomically flat, defect-free, UHV-prepared copper surfaces favour the Hydrogen Evolution Reaction (HER) over the CO$_2$RR.$^6$ Only by introducing defects and high index sites with harsh treatments such as chemical etching, prevalent literature product distributions were observed. In this study, atomically-flat, UHV-prepared Cu(111) surfaces were modified on the mesoscale, rather than at the nanoscale. We found that the introduction of small changes in the surface structure at the mesoscale produces significant selectivity changes in CO$_2$RR. In particular, the product selectivity was found to vary drastically from hydrogen to C$_{2+}$ hydrocarbons as successive CO$_2$RR cycles were applied on the same single crystal, despite the fact that a UHV cleaning treatment was used to regenerate the surface after each cycle.
References
1. Shih, C. F., Zhang, T., Li, J. & Bai, C. Powering the Future with Liquid Sunshine. Joule 2, 1925–1949 (2018).
2. Hori, Y. Electrochemical CO$_2$ Reduction on Metal Electrodes. Mod. Asp. Electrochem. 42, 89–189 (2008).
3. Xiao, C. & Zhang, J. Architectural Design for Enhanced C$_2$Product Selectivity in Electrochemical CO$_2$Reduction Using Cu-Based Catalysts: A Review. ACS Nano 15, 7975-8000 (2021).
4. García de Arquer, F. P. et al. CO$_2$ electrolysis to multicarbon products at activities greater than 1 A cm$^{−2}$. Science 367, 661–666 (2020).
5. Wang, X. et al. Efficient electrically powered CO$_2$-to-ethanol via suppression of deoxygenation. Nat. Energy 5, 478–486 (2020).
6. Scholten, F., Nguyen, K.-L. C., Bruce, J. P., Heyde, M. & Roldán Cuenya, B. Identifying structure‐selectivity correlations in the electrochemical reduction of CO$_2$: comparison of well‐ordered atomically‐clean and chemically‐etched Cu single crystal surfaces. Angew. Chemie Int. Ed. 60, 19169–19175 (2021).
Abstract Number (department-wise) | ISC 06 |
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Department | ISC (Roldán) |