基于固态Ag/AgCl参比电极的氧化钨pH电化学传感器的研究(英文)

Preparation of a Tungsten Oxide pH Electrochemical Sensor Based on Solid Ag/AgCl Reference Electrode

通过浸涂法在钨金属丝上涂敷氧化钨氢离子敏感膜，制备了氧化钨H＋选择性电极，采用尿素改性聚乙烯醇作为参比电极的固态薄膜材料并进行KCl掺杂，经Nafion膜进行修饰后制备了固态参比电极.利用自制的氧化钨pH电极与固态参比电极制成pH电化学传感器，该传感器具有良好的响应电位E-pH线性函数关系，响应范围为pH2~pH11.响应灵敏度与氧化钨的热处理温度有关，200℃热处理后的响应灵敏度为52.81 mV/pH，响应时间与氧化钨敏感膜、测试溶液pH值以及溶液温度有关.在pH2→pH11→pH2循环测试过程中，传感器的滞后效应较小.该传感器有良好的选择性，响应行为不受Na＋、F-等常见离子的影响，但是受到氧化还原性的NO-3、I-等离子的干扰.传感器内阻很低为22.8 kΩ，远小于玻璃pH计的内阻（1×109Ω）.该传感器在各种饮料中具有较高测量精度，与玻璃pH计的测量值进行对比，两者的差值在（-0.06 pH，＋0.15pH）范围内.在10-5M→10-1M柠檬酸溶液中，传感器的响应电位与溶液浓度存在良好的线性关系，响应时间小于1 min.

A pH electrochemical sensor was prepared with a tungsten oxide working electrode and a solid Ag/AgCl reference electrode, and the process to make these working electrode and reference electrode was presented. The prepared tungsten oxide pH sensor has a good E-pH relationship in the range of pH2-pil11. The response time is dependent of the solution pH value and the heat-treated temperature for the tungsten oxide film. The response sensitivity of the pH sensor is related to the heat-treated temperature in the preparation of tungsten oxide H＋ selective film. The hysterisis effect of the sensor could be negligible in the determination loop of pH2→pH11→pH2. The pH sensor also shows the good ion selectivity in several solutions with mixed ions, but it is interfered with the reductive/oxidative ions. The pH sensor has a inner resistance about 22.8 kΩ, much less than it of glass pH electrode （nearly 1×10^9Ω）. The application of the pH sensor in the pH determination in various drinks was studied, and finally, the concentration analysis of lemon acid with this pH sensor was also conducted.