Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) for In-Situ Analysis of Solid Oxide Electrolysis Cells

High temperature co-electrolysis of steam and carbon dioxide using a solid oxide cell (SOC) has been shown to be an efficient route to produce syngas (CO + H₂), which can then be converted to synthetic fuel. Optimization of co-electrolysis requires detailed understanding of the complex reactions, transport processes and degradation mechanisms occurring in the SOC during operation. Currently, electrochemical measurements are conducted in-situ during electrolysis operation, however many analytical techniques are only used ex-situ, before and/or after electrolysis operation. In some cases the analytical techniques used are destructive (e.g. SEM imaging of the cell microstructure). In order to fully understand and characterize co-electrolysis in SOCs, in-situ monitoring of the reactants, products, and the cell itself are necessary.

As part of the UK-wide £5.7m 4CU project (A Comprehensive, Coordinated Programme for Carbon Capture and Utilisation Research) we are developing a suite of in-situ characterization techniques for high temperature SOC operation. In this paper we report the use of DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) to probe the reactions occurring during dry CO₂ electrolysis and co-electrolysis.

The design and commissioning of the rig for in-situ characterization will be presented, along with a discussion on the challenges of spectroscopic access to the areas of interest of an SOC operating at high temperature. Infrared spectra showing CO adsorption on Ni-YSZ powdered catalyst and electrode surfaces will be presented.