MXenes, a family of 2D transition metal carbides, carbonitrides and nitrides, are increasingly being investigated for application in water purification, electronics and electrochemical energy storage whereby ion exchange and intercalation are the dominant fundamental processes at play. This study investigates the energetics of alkali metal ions exchange on a multi-layer clay-like Ti3C2Tx where Tx refers to the anionic mixture of surface terminations, by flow adsorption microcalorimetry. The MXene sample was exposed to alternating aqueous solutions of 0.1 M LiCl, NaCl and KCl at pH 5.60 ±0.02 to obtain the heats associated with the exchange of Na+, K+ and Li+. Furthermore, to systematically study the role that surface moieties play in ion exchange/interaction on MXene, in situ chemical treatments with HCl and NaOH were performed, after which Na+, K+ and Li+ exchanges were measured again. The initial data shows that Li+ replacing Na+ and K+, as well as Na+ replacing K+ were endothermic while Na+ and K+ replacing Li+, and K+ replacing Na+ were exothermic. Although the data correlate with the hydrated ionic radii suggesting a true exchange process, further interpretation and data analysis will be conducted to determine the contribution of ion intercalation and Tx moieties to the overall affinity of alkali metal to the MXene surfaces.

Thermodynamic analysis of alkali metal ions (Li+, Na+, K+) exchange on MXene using flow microcalorimetry

255th National Meeting (2018)

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