This thesis focuses on the synthesis, characterization and performance towards CO2 electroreduction of mono and bi-metallic particles based on p-block metals. With an industrial perspective in mind... Show moreThis thesis focuses on the synthesis, characterization and performance towards CO2 electroreduction of mono and bi-metallic particles based on p-block metals. With an industrial perspective in mind, we try to synthesize particulate, high surface area materials with clean, scalable synthesis methods where possible and test their performance in H-Cell and gas diffusion electrode flow cell configurations. With a combination of characterization techniques, we find possible explanations for the catalytic behaviors. Show less
Cecilio de Oliveira Monteiro, M..; Dieckhöfer S, : Bobrowski, T.; Quast T.; Pavesi, D.; Koper M.T.M.; Schuhmann, W. 2021
Large scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different... Show moreLarge scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different variables are known to affect the performance of GDEs. Especially regarding the catalyst loading, there are diverging trends reported in terms of activity and selectivity, e.g. for CO2 reduction to CO. We have used shear-force based Au nanoelectrode positioning and scanning electrochemical microscopy (SECM) in the surface-generation tip collection mode to evaluate the activity of Au GDEs for CO2 reduction as a function of catalyst loading and CO2 back-pressure. Using a Au nanoelectrode, we have locally measured the amount of CO produced along a catalyst loading gradient under operando conditions. We observed that an optimum local loading of catalyst is necessary to achieve high activities. However, this optimum is directly dependent on the CO2 back-pressure. Our work does not only present a tool to evaluate the activity of GDEs locally, it also allows drawing a more precise picture regarding the effect of catalyst loading and CO2 back-pressure on their performance. Show less
Large scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different... Show moreLarge scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different variables are known to affect the performance of GDEs. Especially regarding the catalyst loading, there are diverging trends reported in terms of activity and selectivity, e.g. for CO2 reduction to CO. We have used shear-force based Au nanoelectrode positioning and scanning electrochemical microscopy (SECM) in the surface-generation tip collection mode to evaluate the activity of Au GDEs for CO2 reduction as a function of catalyst loading and CO2 back pressure. Using a Au nanoelectrode, we have locally measured the amount of CO produced along a catalyst loading gradient under operando conditions. We observed that an optimum local loading of catalyst is necessary to achieve high activities. However, this optimum is directly dependent on the CO2 back pressure. Our work does not only present a tool to evaluate the activity of GDEs locally, it also allows drawing a more precise picture regarding the effect of catalyst loading and CO2 back pressure on their performance. Show less
Pavesi, D.; Poll, R.C.J. van de; Krasovic, J.L.; Figueiredo, M.; Gruter, G.J.M.; Koper, M.T.M.; Schouten, K.J.P. 2020
CO2 electroreduction to formate powered by renewable energy is an attractive strategy to recycle air-based carbon. At the moment, the electrode materials showing high selectivity for formate at... Show moreCO2 electroreduction to formate powered by renewable energy is an attractive strategy to recycle air-based carbon. At the moment, the electrode materials showing high selectivity for formate at high current density are post transition metals such as In, Sn, Bi, and Pb. Scaling up the CO2 electroreduction technology to industrial size requires, among other things, cheap and clean methods to produce cathode materials in the form of particles to fabricate the square meters of the electrode surface area needed for the industrial electrolyzers. We show here that it is possible to easily produce catalytic powders based on Sn and Pb via a process known as cathodic disintegration, driving the reaction with electric power and avoiding the use of organic solvents, stabilizers, and reducing agents. The catalysts produced with this method are highly selective for the reduction of CO2 to formate and show promise for use in industrial electrolyzers. Moreover, the process of cathodic disintegration is quick and clean, it has a high atom efficiency, it uses dilute aqueous electrolytes as solvents, and it has the possibility to be driven by renewable energy. Show less
CO(2)electroreduction powered by renewable energy is an attractive strategy to recycle air-based carbon. One of the current challenges for the scale up of the technology is that the catalysts that... Show moreCO(2)electroreduction powered by renewable energy is an attractive strategy to recycle air-based carbon. One of the current challenges for the scale up of the technology is that the catalysts that show high faradaic yield at high current density (post-transitional metals such as In, Sn, Bi, Pb) suffer from very high overpotentials of more than 1 V. On the other hand, Pd can convert CO(2)to formate with almost no overpotential, but is readily poisoned by CO and deactivates when trying to reach industrially relevant currents. In this work we show the effect of the interaction of In and Pd in bimetallic nanoparticles, reaching the conclusion that this interaction causes a loss of selectivity towards formate and at the same time suppresses CO poisoning of Pd sites. The results of the catalyst characterization suggest the formation of intermetallic PdIn compounds that in turn cause the aforementioned behavior. Based on these results, it seems that geometric and electronic effects in Pd based intermetallic compounds can alleviate CO poisoning on Pd sites. In the case of PdIn intermetallics this leads to the loss of CO(2)reduction activity, but this strategy may be useful for other electrochemical reactions that suffer from the same problem of deactivation. It remains to be seen if intermetallic compounds of Pd with other elements can yield viable CO(2)reduction catalysts. Show less
