High-lateral resolution X-ray fluorescence microspectroscopy and dynamic mathematical modelling as tools for the study of electrodeposited electrocatalysts

In this paper, we report on the use of high-space resolution soft X-ray fluorescence microspectroscopy for the study of electrodeposited composites containing catalytic ternary metal nanostructures. X-ray fluorescence maps are interpreted in terms of a dynamic mathematical model of the electrode morphology and metal space distribution, allowing to reproduce the observed space patterns and electrochemical transients by assigning an appropriate set of electrokinetic parameters. The discussed materials-science case is the electrochemical growth of a Mn-Mg-Cu-polypyrrole nanocomposite electrocatalyst material - free of expensive Pt and environmentally unfriendly Co - with promising performance for fuel-cell oxygen electrodes. The synergy of high-resolution compositional mapping with electrokinetic modelling not only provides the general rationale for quantitative use of potentially large compositional distribution datasets but also yields unprecedented insight into the specific catalyst synthesis process. The expounded application is just a prototypical case study of a more general approach, which can be employed for the understanding of electrochemical material science processes, both in situ and ex situ, as well as for the characterisation of the corresponding products, with no other limitations in principle than X-ray transmission and beam damage