SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 96: Solid-Liquid Interfaces III: Reactions and Electrochemistry II
O 96.3: Vortrag
Freitag, 31. März 2023, 11:00–11:15, TRE Phy
Modeling Transport Effects on Selectivity in Electrochemical CO2 Reduction — •Hendrik H. Heenen1,2, Georg Kastlunger2, Vanessa J. Bukas1, Karsten Reuter1, and Karen Chan2 — 1Fritz-Haber-Institut der MPG, Berlin, Germany — 2Technical University of Denmark, Lyngby, Denmark
Product selectivity in the electrochemical CO2 reduction reaction (eCO2RR) is known to change considerably with non-obvious parameters such as catalyst morphology or reactor design. In this work we explore the proposition that these parameters are related to selectivity through transport mediated desorption and adsorption of key intermediates. The mesoscopic morphology of a catalyst can be characterized by a measurable loading or roughness which determines the so-called active surface area. This area may in turn determine the selectivity by controlling the fate of desorbing (closed shell) intermediates along the reaction path: either to re-adsorb and further react on the surface, or to entirely leave the catalyst surface and form an early not fully-reduced product. We specifically show this competition in the reaction toward acetate which we propose to be governed by a solution reaction. Combining ab initio energetics, microkinetic and transport modeling in a multi-scale approach, we predict complex selectivity toward acetate with almost quantitative agreement to experiment. Finally, we demonstrate that the same principle applies to other important intermediates in the eCO2RR. Mesoscopic transport thus provides an alternative or, at least, complementary explanation to changes in selectivity that are otherwise attributed to active sites changes, to doping, or to alloying.