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Designing Selective Electrode Materials for Electroanalysis –New Tungsten Bronzes as Selective Potassium Hosts
Author(s) -
Chen Yuqi,
Yang Minjun,
Cooper Joshaniel F. K.,
Clarke Simon J.,
Rasche Bertold,
Compton Richard G.
Publication year - 2020
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.202000851
Subject(s) - potassium , tungsten , monoclinic crystal system , cyclic voltammetry , aqueous solution , selectivity , inorganic chemistry , chemistry , electrode , phase (matter) , materials science , electrochemistry , crystal structure , crystallography , organic chemistry , catalysis
Commercially available monoclinic tungsten oxide WO 3 (Pearson symbol mP 32) is investigated electrochemically for its selectivity and sensitivity towards potassium ion detection. Electroreduction in aqueous potassium chloride solution shows two distinct phases, identified as tungsten bronzes K x WO 3 (phase 1: maximum x 1 ≈ 0.1 and phase 2: maximum x 2 ≈0.3). In situ synchrotron powder X‐ray diffraction reveals the concomitant structural changes, and both phases are identified as new, so far unreported, perovskite‐derived potassium bronzes (space group P 4/ nmm and I 4 ‾ 3 m , respectively). In cyclic voltammetry, only the first insertion step is found to be reversible. Potentiostatic insertion and the subsequent voltammetric de‐insertion show selectivity toward potassium against lithium and sodium in 0.1 M aqueous solutions. The sensitivity towards potassium is analysed in a concentration range between 1 mM and 100 mM. Two linear regions are found for the response, which we relate to two different rate‐determining steps, depending on the concentration of potassium in solution.