基于SBS-EGaIn修饰柔性IrOx电极的土壤pH值原位监测方法

In-situ Soil pH Monitoring Using SBS-EGaIn Modified Flexible IrOx Electrode

摘要:

为了应对柔性氧化铱(IrOx)电极在pH值测量过程中易过度水合和韧性不足导致检测电位波动的问题，本文提出了一种液态金属纤维(SBS-EGaIn)修饰的柔性IrOx电极，并对其进行了制备与测试。通过组分分析和微观形貌表征，比较分析了SBS-EGaIn功能涂层的疏水特性对IrOx水合反应的抑制效果及其作用机制。进一步系统评估了SBS-EGaIn修饰的柔性IrOx电极在灵敏度、响应时间、重复性、长期稳定性等电化学性能参数方面的表现，并通过疲劳测试验证了其在长期使用中的耐久性。试验结果表明，当pH值为3.3~9.8时，该电极灵敏度为-62.50 mV/pH，响应时间为60 s，电位漂移小于1×10-3 mV/s，对土壤中大量及微量离子的选择性系数小于1×10-7，表现出良好的重复性、抗干扰性和稳定性。此外，为进一步评估其在实际应用中的性能，进行了为期30 d的土柱监测试验。柔性pH电极检测值与标准玻璃电极测量值高度一致，误差不超过0.1。不同土壤含水率条件下，柔性pH电极与标准pH电极监测值Cronbach's α均不小于0.969，表明存在较高一致性。

Abstract:

Aiming to address the issues of excessive hydration and insufficient toughness of flexible iridium oxide (IrOx) electrodes during pH measurement, which often lead to potential fluctuations, a flexible IrOx electrode modified with a liquid metal fiber (SBS-EGaIn) was proposed. The preparation and characterization of the proposed electrode were presented. Through compositional analysis and morphological characterization, the hydrophobic properties of the SBS-EGaIn functional coating and its inhibitory effect on the hydration reaction of IrOx were investigated, along with the underlying mechanism. The electrochemical performance of the SBS-EGaIn-modified flexible IrOx electrode was systematically evaluated in terms of sensitivity, response time, repeatability, and long-term stability. Additionally, its durability under prolonged use was verified through fatigue tests. Experimental results showed that, within a pH value range of 3.3 to 9.8, the electrode exhibited a sensitivity of -62.50 mV/pH, a response time of 60 s, and a potential drift of less than 1×10-3 mV/s. The selectivity coefficients for common ions (both macro and trace elements) in soil were below 1×10-7, indicating good repeatability, anti-interference ability, and stability. To further evaluate its practical applicability, a 30-days soil column monitoring experiment was conducted. The pH values measured by the flexible electrode were highly consistent with those obtained using a standard glass electrode, with a deviation of less than 0.1. Under different soil moisture conditions, the Cronbach's α values between the flexible pH electrode and the standard pH electrode were all no less than 0.969, demonstrating a high level of consistency.