Designing Selective Electrode Materials for Electroanalysis –New Tungsten Bronzes as Selective Potassium Hosts.

Chen, Yuqi; Yang, Minjun; Cooper, Joshaniel F. K.; Clarke, Simon J.; Rasche, Bertold; Compton, Richard G.

Commercially available monoclinic tungsten oxide WO3 (Pearson symbol mP32) 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 KxWO3 (phase 1: maximum x1≈ 0.1 and phase 2: maximum x2≈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 P4/nmm and I4‾ 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.

TUNGSTEN bronze; POTASSIUM ions; ELECTROCHEMICAL analysis; POTASSIUM; X-ray powder diffraction; TUNGSTEN oxides; CYCLIC voltammetry

ChemElectroChem, 2020, Vol 7, Issue 14, p3160

2196-0216

Academic Journal

10.1002/celc.202000851