Speakers
Description
Electrochemical reduction of CO$_2$ (CO$_2$RR) is an attractive technology to turn undesired CO$_2$ back into the carbon cycle driven by renewable energy and a suitable catalyst. Cu$_2$O nanocubes have been shown to be a promising catalyst by converting CO$_2$ into multiple C$_{2+}$ hydrocarbons.$^1$ Thus, an essential challenge is to control the selectivity toward particular products. Several approaches have been tested so far to improve the selectivity trends, such as varying catalyst structure, electrolyte composition or the potential sequence.$^2$ One promising way to further improve the catalyst performance and selectivity is the introduction of a second metal. Recent studies of Cu-Ag and Cu-Au bimetallic systems showed enhanced selectivity for ethanol and/or ethylene, which was usually accompanied by the increased production of CO.$^{3,4}$
In this study, we prepared Ag- and Au-decorated Cu$_2$O nanocubes with 30 nm edge length through a facile wet-chemical, ligand-free synthesis and got insight into the morphology, chemical state, and composition of the catalysts by means of ex-situ, quasi-in situ and operando characterization techniques. On one hand, by the addition of Ag nanoparticles (NPs) on Cu$_2$O nanocubes, we could double the Faradaic efficiency of liquid products, while observing a dispersion of the Ag on Cu and the formation of a Cu-Ag during CO$_2$RR.$^5$ On the other hand, by the addition of Au NPs with different loadings on Cu$_2$O nanocubes, a correlation between the CO environment, the simultaneous alloying and the catalytic performance was established. Transmission electron spectroscopy (TEM) as well as quasi in situ X-ray photoelectron spectroscopy (XPS) demonstrated an alteration in phase, structure and composition, while operando methods, such as X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD) and operando surface enhanced Raman spectroscopy (SERS) uncovered the continuous evolution of the local structure and chemical environment as well as the modification of the CO-intermediate on Cu.
These studies highlight the importance of operando investigations to unravel the catalyst’s adaptations and intermediates during reaction and demonstrate the deconvolution of the complex interplay between phase mixing, alloy formation and the modification of the CO binding on Cu.
References
1. Y. Hori, K. Kikuchi, S. Suzuki, Chem. Lett. 14, 1695 (1985).
2. H.S. Jeon, J. Timoshenko, C. Rettenmaier, A. Herzog, A. Yoon, S.W. Chee, S. Oener, U. Hejral, F.T. Haase, B. Roldan Cuenya, J. Am. Chem. Soc. 143, 7578 (2021).
3. C. Kim, T. Eom, M. S. Jee, H. Jung, H. Kim, B. K. Min, ACS Catal. 7, 779 (2017).
4. D. Ren, J. Gao, L. Pan, Z. Wang, J. Luo, S. M. Zakeeruddin, A. Hagfeldt, M. Grätzel, Angew. Chem. 131, 15178 (2019).
5. A. Herzog, A. Bergmann, H.S. Jeon, J. Timoshenko, S. Kühl, C. Rettenmaier, M. Lopez Luna, F.T. Haase, B. Roldan Cuenya, Angew. Chem. Int. Ed. 60, 7426 (2021).
| Abstract Number (department-wise) | ISC 02 |
|---|---|
| Department | ISC (Roldán) |
