Leuven | More than two weeks ago
Anthropogenic CO2, originating from e.g., power generation, transportation, or agricultural practices, is a main contributor to global warming. Increased environmental awareness compounded by the ever-increasing demand for energy, necessitate innovative solutions for lowering CO2 emissions. At imec, we see low temperature electrochemical valorization of CO2 as a promising technology. Copper is the only monometallic electro-catalyst known to reduce CO2 into high value multi-carbon products. There are numerous studies that report the high conversion efficiency of copper-based catalysts. Often, however, the reported values are not in steady state, but are merely the maximum value observed directly after starting electrolysis. Although lack of long-term stability, is a widely cited problem, there are limited studies on the origin of catalyst degradation. Beyond structural changes of the catalyst, the accumulation of poisons, from e.g., cell housing, on the surface that block active sites could result in the degradation. Classically, electrochemical reactions are carried out in glassware (borosilicate). Silica is a known ubiquitous poison of high temperature electrochemical systems and there is some indication in literature that Si-impurities from glassware result in degradation of the Cu-catalyst.1–3 Recently, however, it was found that the intentional integration of silica onto the copper catalyst resulted in increased carbon-carbon coupling towards ethylene electrosynthesis.4
The goal of this master’s project is to consolidate these seemingly conflicting findings. The effect of silica on the widely used electrocatalyst copper will be systematically examined. The results attained in a Si-free system, will be compared to the those attained when silica is added directly to the electrolyte or when using copper onto which Si-has been added to the surface. Insights into the morphological effects of the additive will be gained by comparing sol gel deposited silica to highly order mesoporous layers made electrochemically assisted self-assembly.5,6 Beyond gaining experience in electrochemistry, you will also use in situ Raman spectroscopy to examine changes in the copper surface chemistry due to the Si-species. The evolution of CO2 electrolysis products will be monitored using chromatography. The work will be executed in the labs at imec.
1. Bertheussen, E. et al. Electroreduction of CO on Polycrystalline Copper at Low Overpotentials. ACS Energy Letters 3, 634–640 (2018).
2. Tiwari, A., Maagaard, T., Chorkendorff, I. & Horch, S. Effect of Dissolved Glassware on the Structure-Sensitive Part of the Cu(111) Voltammogram in KOH. ACS Energy Letters 4, 1645–1649 (2019).
3. Staerz, A., Seo, H. G., Defferriere, T. & Tuller, H. L. Silica: ubiquitous poison of metal oxide interfaces. Journal of Materials Chemistry A (2022).
4. Li, J. et al. Silica-copper catalyst interfaces enable carbon-carbon coupling towards ethylene electrosynthesis. Nature Communications 12, (2021).
5. Kajihara, K. Recent advances in sol-gel synthesis of monolithic silica and silica-based glasses. Journal of Asian Ceramic Societies vol. 1 121–133 (2013).
6. Vanheusden, G., Philipsen, H., Herregods, S. J. F. & Vereecken, P. M. Aggregate-Free Micrometer-Thick Mesoporous Silica Thin Films on Planar and Three-Dimensional Structured Electrodes by Hydrodynamic Diffusion Layer Control during Electrochemically Assisted Self-Assembly. Chemistry of Materials 33, 7075–7088 (2021).
7. Mayrhofer, K. J. J., Crampton, A. S., Wiberg, G. K. H. & Arenz, M. Analysis of the Impact of Individual Glass Constituents on Electrocatalysis on Pt Electrodes in Alkaline Solution. Journal of The Electrochemical Society 155, P78 (2008).
Type of project: Internship, Thesis
Duration: 1 year
Required degree: Master of Bioengineering
Required background: Bioscience Engineering
Supervising scientist(s): For further information or for application, please contact: Anna Staerz (Anna.Staerz@imec.be)
Only for self-supporting students.