Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering.
Gihan KwonYeong Ho ChoKi Bum KimJonathan D EmeryIn Soo KimXiaoyi ZhangAlex B F MartinsonDavid M TiedePublished in: Journal of synchrotron radiation (2019)
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 µm-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 of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.
Keyphrases
- metal organic framework
- solid state
- high resolution
- carbon nanotubes
- room temperature
- highly efficient
- ionic liquid
- photodynamic therapy
- gold nanoparticles
- reduced graphene oxide
- single cell
- tissue engineering
- dual energy
- cell therapy
- label free
- electron transfer
- light emitting
- oxide nanoparticles
- molecular dynamics simulations
- mass spectrometry
- magnetic resonance imaging
- stem cells
- magnetic resonance
- computed tomography
- optical coherence tomography
- air pollution
- mesenchymal stem cells
- soft tissue