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Potential‐Dependent, Switchable Ion Selectivity in Aqueous Media Using Titanium Disulfide
Author(s) -
Srimuk Pattarachai,
Lee Juhan,
Fleischmann Simon,
Aslan Mesut,
Kim Choonsoo,
Presser Volker
Publication year - 2018
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201800452
Subject(s) - selectivity , intercalation (chemistry) , electrochemistry , chemistry , aqueous solution , inorganic chemistry , ion , electrode , metal ions in aqueous solution , materials science , organic chemistry , catalysis
The selective removal of ions by an electrochemical process is a promising approach to enable various water‐treatment applications such as water softening or heavy‐metal removal. Ion intercalation materials have been investigated for their intrinsic ability to prefer one specific ion over others, showing a preference for (small) monovalent ions over multivalent species. In this work, we present a fundamentally different approach: tunable ion selectivity not by modifying the electrode material, but by changing the operational voltage. We used titanium disulfide, which shows distinctly different potentials for the intercalation of different cations and formed binder‐free composite electrodes with carbon nanotubes. Capitalizing on this potential difference, we demonstrated controllable cation selectivity by online monitoring the effluent stream during electrochemical operation by inductively coupled plasma optical emission spectrometry of aqueous 50 m m CsCl and MgCl 2 . We obtained a molar selectivity of Mg 2+ over Cs + of 31 (strong Mg preference) in the potential range between −396 mV and −220 mV versus Ag/AgCl. By adjusting the operational potential window from −219 mV to +26 mV versus Ag/AgCl, Cs + was preferred over Mg 2+ by 1.7 times (Cs preference).