基于固态Ag/AgCl参比电极的氧化钨pH电化学传感器的研究

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(1×109 Ω).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, 0.15 pH)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.

Preparation of a Tungsten oxide pH electrochemical sensor based on solid Ag/AgCl reference electrode

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～pH11.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 1×109 Ω). 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.