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O: Fachverband Oberflächenphysik

O 96: Solid-Liquid Interfaces IV: Reactions and Electrochemistry

O 96.6: Vortrag

Donnerstag, 21. März 2024, 16:30–16:45, TC 006

Relation between Electrocatalyst Morphology and Product Selectivity from Multi-Scale Reaction Models — •Hemanth S. Pillai, Hendrik H. Heenen, Karsten Reuter, and Vanessa J. Bukas — Fritz-Haber-Institut der MPG, Berlin

Electrocatalytic selectivity has shown a puzzling dependence on experimental parameters related to catalyst morphology. We argue that such effects can often be rationalized on the basis of mesoscopic mass transport. Basis for the underlying mechanism is the competition that arises from exchanging surface-bound, yet volatile, reaction intermediates between the electrode and the bulk electrolyte. The catalyst morphology can be decisive in driving this competition since its surface area directly affects the probability that a diffusing species will return to the surface for continued conversion, rather than escape as an early intermediate product. It remains unclear, however, exactly how catalyst morphology is predicted to affect the resulting selectivity and neither is the level of detail that needs to be considered. In this study, we specifically demonstrate this competition for the electrochemical CO₂ reduction on Cu. For this purpose, we develop a simple multi-scale model that couples diffusion to the electrochemical surface kinetics. This allows to predict selectivity towards the early CO product, while systematically improving the representation of catalyst morphology within our model: from an effective one-dimensional descriptor of surface roughness, to an explicit two-dimensional consideration of surface corrugation.

Keywords: electrocatalysis; mass transport; mechanism; model; density functional theory