Open‐source electrochemical cell for in situ X‐ray absorption spectroscopy in transmission and fluorescence modes

• Published in: Journal of synchrotron radiation Vol. 31; no. 2; pp. 322 - 327
• Main Authors: Lopez-Astacio, Hiram, Vargas-Perez, Brenda Lee, Del Valle-Perez, Angelica, Pollock, Christopher J., Cunci, Lisandro
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.03.2024; John Wiley & Sons, Inc; International Union of Crystallography (IUCr)
• Subjects: Absorption spectroscopy; Carbon; Electrochemical cells; electrochemical cells for in situ XAS; Electrochemistry; EXAFS; Fluorescence; Numerical controls; Ohmic drop; ORR catalysts; Oxygen; Purging; Reaction kinetics; Reaction mechanisms; Research Papers; Spectrum analysis; ORR catalysts; electrochemical cells for in situ XAS; EXAFS
• ISSN: 1600-5775; 0909-0495; 1600-5775
• DOI: 10.1107/S1600577524000122

X‐ray spectroscopy is a valuable technique for the study of many materials systems. Characterizing reactions in situ and operando can reveal complex reaction kinetics, which is crucial to understanding active site composition and reaction mechanisms. In this project, the design, fabrication and testing of an open‐source and easy‐to‐fabricate electrochemical cell for in situ electrochemistry compatible with X‐ray absorption spectroscopy in both transmission and fluorescence modes are accomplished via windows with large opening angles on both the upstream and downstream sides of the cell. Using a hobbyist computer numerical control machine and free 3D CAD software, anyone can make a reliable electrochemical cell using this design. Onion‐like carbon nanoparticles, with a 1:3 iron‐to‐cobalt ratio, were drop‐coated onto carbon paper for testing in situ X‐ray absorption spectroscopy. Cyclic voltammetry of the carbon paper showed the expected behavior, with no increased ohmic drop, even in sandwiched cells. Chronoamperometry was used to apply 0.4 V versus reversible hydrogen electrode, with and without 15 min of oxygen purging to ensure that the electrochemical cell does not provide any artefacts due to gas purging. The XANES and EXAFS spectra showed no differences with and without oxygen, as expected at 0.4 V, without any artefacts due to gas purging. The development of this open‐source electrochemical cell design allows for improved collection of in situ X‐ray absorption spectroscopy data and enables researchers to perform both transmission and fluorescence simultaneously. It additionally addresses key practical considerations including gas purging, reduced ionic resistance and leak prevention. An economical and easy‐to‐fabricate electrochemical cell for in situ X‐ray absorption spectroscopy was developed, fabricated, and used to obtain XANES and EXAFS data for a catalyst for the oxygen reduction reaction. The experiments were run with and without oxygen purging using an attachment that avoids interactions between bubbles and the working electrode, and X‐ray absorption spectroscopy data were obtained under applied potential and with and without gas purging, showing the capabilities of this electrochemical cell for in situ experiments.