Commercially available monoclinic tungsten oxide WO₃ (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 WO₃ (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 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.

中文翻译：

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设计用于电分析的选择性电极材料-新型钨青铜作为选择性钾基质

用电化学方法研究了市售的单斜氧化钨WO ₃（Pearson符号mP 32）的选择性和对钾离子检测的敏感性。电还原中氯化钾水溶液显示了两个不同的相，经鉴定为钨青铜ķ _X WO ₃（相1：最大X ₁ 0.1和相位2：最大X ₂ ≈0.3）。原位同步加速器粉末X射线衍射显示伴随的结构变化，并且两个相都被鉴定为新的，迄今未报道的钙钛矿衍生的钾青铜（空间群P 4 / nmm和I 3  m， 分别）。在循环伏安法中，只有第一个插入步骤是可逆的。恒电位插入和随后的伏安解插表明在0.1 M水溶液中钾对锂和钠的选择性。在1 mM和100 mM之间的浓度范围内分析对钾的敏感性。找到了两个线性区域用于响应，这取决于溶液中钾的浓度，与两个不同的速率确定步骤有关。