Regensburg 2016 – wissenschaftliches Programm

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AKE: Arbeitskreis Energie

AKE 8: CO₂ Electro-Reduction

AKE 8.1: Vortrag

Montag, 7. März 2016, 17:15–17:30, H3

Monitoring the Chemical State of Catalysts for CO2 Electroreduction: An in operando Raman spectroscopic Study — •Akiyoshi Kuzume, Abhijit Dutta, Motiar Rahaman, and Peter Broekmann — Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland

A major concern of electrocatalysis research is to assess the structural and chemical changes that a catalyst may itself undergo in the course of the catalyzed process. These changes can influence not only the activity of the studied catalyst, but also its selectivity towards the formation of a certain product. An illustrative example is the electroreduction of carbon dioxide on tin oxide nanoparticles, where under the operating conditions of the electrolysis (that is, at cathodic potentials) the catalyst undergoes structural changes which in an extreme case involves its reduction to metallic tin. This results in a decreased Faradaic efficiency (FE) for the production of formate (HCOO*) that is otherwise the main product of CO2 reduction on SnOx surfaces. In this study we utilized potential and time dependent in operando Raman spectroscopy in order to monitor the oxidation state changes of SnO2 that accompany CO2 reduction. Investigations were carried out at different alkaline pH levels, and a strong correlation between the oxidation state of the surface and the FE of HCOO* formation was found. Understanding the transition of phases, such as oxide to metallic or vice versa, during CO2 electrolysis can offer distinct benefits of the catalyst material in terms of activity, selectivity, and stability.