Nanostructured Metals: Advanced Electrocatalysts for Carbon Dioxide Reduction
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, E-mail: firstname.lastname@example.org
Due to rising energy demand and evidence of the environmental effects of CO2 emissions, much research has focused on producing and storing energy from renewable sources. An efficient and selective process for the conversion of CO2 to CO or other reduced products could allow for the widespread production of liquid fuels. Coupled with renewable energy sources, these processes could help solve the large scale storage issue of renewable energies while creating a carbon neutral energy source easily integrated into the current energy infrastructure. To date, researchers have identified several bulk metal catalysts such as Cu, Ag, Au, and Zn that are able to reduce CO2 electrochemically in aqueous electrolytes albeit requiring significant energy from an external source (i.e. overpotential) to drive the reaction
Nanostructured catalysts are of great interest for CO2 to CO conversion due to their high catalytic surface area and unique properties relative to their polycrystalline counterparts. In this presentation, we will discuss our recent discovery of a highly active nanoporous Ag electrocatalyst, which is able to reduce CO2 electrochemically to CO in a highly efficient and selective way. Not only the porous structure creates an extremely large surface area for catalytic reaction, but also the curved internal surface generates a large number of highly active step sites for CO2 conversion, resulting in an exceptional activity that is over three orders of magnitude higher than that of the polycrystalline counterpart at a moderate overpotential of < 500 mV. More importantly, such a remarkable activity for CO2 electroreduction has been achieved with a CO Faradaic efficiency of 92%. We will discuss our recent work to explore the origin of the superior activity of nanostructured Ag.
Considering the cost of Ag, we also investigated nanostructured Zn catalyst. Using electrodeposition technique, we are able to develop a dendritic Zn catalyst, which is able to selectively reduce CO2 at rates around an order of magnitude higher than bulk Zn with great long term stability. We characterized the behavior of the Zn catalyst during CO2 electrolysis using in-situ/operando X-ray absorption spectroscopy, which provided us insight into the oxidation state and coordination of the dendritic Zn catalyst at working conditions.
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