Zooming‐in – Visualization of active site heterogeneity in high entropy alloy electrocatalysts using scanning electrochemical cell microscopy

Autor: Corina Andronescu, Wolfgang Schuhmann, Bin Xiao, Swapnil Varhade, Simon Schumacher, Olga A. Krysiak, Lars Banko, Alan Savan, Alfred Ludwig, Tobias Löffler, Emmanuel Batsa Tetteh
Rok vydání: 2021
Předmět:
Zdroj: Electrochemical Science Advances
ISSN: 2698-5977
Popis: Complex solid solutions (“high entropy alloys” with a single solid-solution phase) hold great promise in electrocatalysis because of their nearly unlim- ited number of different active sites exposed at the surface. It has been shown by theoretical studies that multiple arrangements of different elements directly neighboring a binding site create millions of differently active catalytic sites. We report a zooming-in approach using scanning electrochemical cell microscopy (SECCM) to distinguish between the averaged electrochemical response of mul- tiple active sites and active site-specific electrochemical response. Using a thin film complex solid solution electrocatalyst and a range of SECCM single bar- rel capillaries with diameters from 1.2 µm to 50 nm, we observed an averaged electrochemical response for the oxygen reduction reaction with minor statisti- cal variations for the larger capillary diameters. In contrast, significant statistical heterogeneity among the measured spots is observed for small capillary diame- ters. This statistical heterogeneity is attributed to the ability of the smaller probe size to address a comparatively smaller number of active sites with high or low activity dominating the measured electrocatalytic currents.  
Databáze: OpenAIRE
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