Scanning electrochemical cell microscopy (SECCM) is the only technique which allows the study of a material using well-established bulk electrochemical techniques with a resolution of a few micrometer down to the nanometer regime. The measurement takes place in a nano- or microdroplet formed at the end of a nano- or micropipette in contact with the surface of interest. This allows e.g. study of single nanoparticle agglomerates or generally spatially resolved analysis of the sample. The analysis of the data is equivalent to the bulk experiment and often straightforward.

In this paper “Mapping Localized Peroxyl Radical Generation on a PEM Fuel Cell Catalyst Using Integrated Scanning Electrochemical Cell Microspectroscopy” by J. Edgecomb et al. SECCM using a HEKA ElProScan platform was combined with adsorption and fluorescence microscopy allowing the recording of spectra within a 10 µm wetted sample area. A fluorescent dye 6CFL was used to detect the generation of peroxyl radicals during the ORR at the non-Pt catalyst TaTiOx on a Nafion membrane which were indeed formed.

The measurements using this integrated SECCM setup were validated by RRDE bulk measurements and can further be applied to novel fuel cell catalysts.

Edgecomb J, Xie X, Shao Y, El-Khoury PZ, Johnson GE and Prabhakaran V (2020) Mapping Localized Peroxyl Radical Generation on a PEM Fuel Cell Catalyst Using Integrated Scanning Electrochemical Cell Microspectroscopy.
Front. Chem. 8:572563. doi: 10.3389/fchem.2020.572563

Scheme of the SECCM setup with integrated spectrometer for adsorption and fluorescence microspectroscopy in the droplet (left), fluorescence spectra within the droplet of a Nafion membrane with a layer of fluorescence dye 6CFL and active catalyst (middle) and fluorescence intensity during ORR at the active catalyst (right). Reproduced from J. Edgecomb et al. (2020) Front. Chem. 8:572563. Copyright by © 2020 Edgecomb, Xie, Shao, El-Khoury, Johnson and Prabhakaran.

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