Regensburg 2019 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 22: Materials for Energy Storage and Conversion

MM 22.11: Vortrag

Mittwoch, 3. April 2019, 13:00–13:15, H43

Effect of mixed surface terminations on the structural and electrochemical properties of two-dimensional Ti3C2T2 and V2CT2 MXenes multilayers — •Nuala Mai Caffrey — School of Physics & CRANN, Trinity College, Dublin 2

MXenes, a family of layered transition metal carbides and nitrides, have shown great promise for use in emerging electrochemical energy storage devices, including batteries and supercapacitors [1]. However, MXene surfaces are terminated by randomly distributed –O, –F and –OH functional groups and there is considerable debate regarding how the intercalating alkali metal ions interact with these functional groups. For instance, their measured Li or Na capacity is far lower than that predicted by theoretical simulations, which generally assume uniformly terminated surfaces. The extent to which this structural simplification contributes to such discrepancies is unknown.

I address this issue by employing first-principles calculations to compare the structural, electronic and electrochemical properties of two common MXenes, namely Ti3C2T2 and V2CT2, with both uniform terminating groups and explicitly mixed terminations [2]. I find that the redox reaction is confined to the terminating groups for low concentrations of intercalated metal ions, with the oxidation state of the metal atoms unaffected until higher concentrations are achieved, in excellent agreement with experiment.

[1] Anasori et al, Nature Reviews Materials 2 16098 (2017)

[2] Caffrey, Nanoscale 10 13520 (2018)

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