In situ XANES and EXAFS Analysis of Redox Active Fe Center Ionic Liquids

Journal Article · Fri Oct 23 00:00:00 EDT 2015 · Electrochimica Acta

DOI:https://doi.org/10.1016/j.electacta.2015.09.093· OSTI ID:1338380

Apblett, Christopher A.  ^[1]; Stewart, David M. ^[2]; Fryer, Robert T. ^[2]; Sell, Julia C. ^[2]; Pratt, Harry D. III ^[3]; Anderson, Travis M. ^[3]; Meulenberg, Robert W. ^[2]

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1. Joint Center for Energy Storage Reseach, Albuquerque, NM (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Technology Group
2. Univ. of Maine, Orono, ME (United States). Dept. of Physics and Astronomy
3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Technology Group

We apply in situ X-Ray Absorption Near Edge Spectroscopy (XANES) and Extended X-Ray Absorption Fine Structure (EXAFS) techniques to a metal center ionic liquid undergoing oxidation and reduction in a three electrode spectroscopic cell. Furthermore, the determination of the extent of reduction under negative bias on the working electrode and the extent of oxidation are determined after pulse voltammetry to quiescence. While the ionic liquid undergoes full oxidation, it undergoes only partial reduction, likely due to transport issues on the timescale of the experiment. Nearest neighbor Fe-O distances in the fully oxidized state match well to expected values for similarly coordinated solids, but reduction does not result in an extension of the Fe-O bond length, as would be expected from comparisons to the solid phase. Instead, little change in bond length is observed. Finally, we suggest that this may be due to a more complex interaction between the monodentate ligands of the metal center anion and the surrounding charge cloud, rather than straightforward electrostatics between the metal center and the nearest neighbor grouping.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Electricity (OE)
• Grant/Contract Number: AC04-94AL85000; AC02-98CH10886
• OSTI ID: 1338380
• Alternate ID(s): OSTI ID: 1359034
• Report Number(s): SAND2016-12355J; 649726
• Journal Information: Electrochimica Acta, Vol. 185, Issue C; ISSN 0013-4686
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
25 ENERGY STORAGE
Electrochemistry
in situ XANES
in situ EXAFS
Redox active Ionic Liquids
Flow Batteries