SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 65: Poster Session V: Solid-liquid interfaces: Reactions and electrochemistry II
O 65.2: Poster
Mittwoch, 3. März 2021, 10:30–12:30, P
Nanostructuring Cu tunes CO(2)R selectivity through the mass transport of products: the example of acetate — •Hendrik H. Heenen1, Georg Kastlunger1, Haeun Shin2, Sean Overa2, Joseph A. Gauthier3, Feng Jiao2, and Karen Chan1 — 1Department of Physics, Technical University of Denmark — 2Department of Chemical and Biomolecular Engineering, University of Delaware — 3Department of Chemical Engineering, Stanford University
Nanostructured Cu catalysts have increased the yield of and lowered the overpotential for high value C-C coupled (C2+) products in electrochemical CO reduction (CORR). With this type of catalyst also the selectivity among C2+ products has changed where acetate has emerged as a major product depending strongly on alkalinity and catalyst structure. This striking selectivity dependence is far from being understood. In this work, we elucidate the mechanism towards acetate using an ab-initio derived microkinetic model coupled to mass transport as well as loading experiments. We find that acetate selectivity is only dependent on local mass transport properties of the catalyst and not founded in changes of the intrinsic activity of Cu. The selectivity mechanism originates in the transport of ketene away from the catalyst surface. This unprecedented mechanism may also explain similar selectivity fluctuations observed for other saturated intermediates like CO and acetaldehyde. Our proposed mechanism explains changes in selectivity of acetate with potential, pH, and catalyst roughness which are the basis for design principles of a selective CORR operation.