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Designing selective electrode materials for electroanalysis – new tungsten bronzes as selective potassium hosts

DOI: 10.1002/celc.202000851 DOI Help

Authors: Yuqi Chen (University of Oxford) , Minjun Yang (University of Oxford) , Joshaniel F. K. Cooper (ISIS Neutron and Muon Source) , Simon J. Clarke (University of Oxford) , Bertold Rasche (University of Cologne) , Richard G. Compton (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemelectrochem

State: Published (Approved)
Published: June 2020
Diamond Proposal Number(s): 20638

Open Access Open Access

Abstract: Commercially available monoclinic tungsten oxide WO3 (Pearson symbol mP32) is investigated electrochemically for its selectivity and sensitivity towards potassium ion detection. Electro‐reduction 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 I–43 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.

Journal Keywords: Voltammetry; in-situ X-ray diffraction; intercalation; potassium; tungsten

Subject Areas: Chemistry, Materials, Energy

Instruments: I11-High Resolution Powder Diffraction