Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50   keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40   nm – 50   nm crystalline indium tin oxide or a 100   nm – 150   nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2   Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60   nm when deposited on a porous electrode with 40   µ m-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure – function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis o...
Source: Journal of Synchrotron Radiation - Category: Physics Authors: Tags: atomic layer deposition electrode architectures pair distribution functions high-energy X-ray scattering catalysts electrochemistry ultra-thin films research papers Source Type: research