Pt/IrO_(x)-pH超微电化学传感器性能探究及其在铜/不锈钢电偶腐蚀研究中的应用

Performance of Pt/IrO_(x)-pH Ultra-micro Electrochemical Sensor and its Application in Study of Galvanic Corrosion of Copper/Stainless Steel

通过在直径10μm铂超微电极表面电化学沉积一层氧化铱薄膜,获得具有pH响应的全固态铂/氧化铱(Pt/IrO_(x))电化学微传感器,分析了其线性响应、瞬时响应、稳定性和抗典型离子干扰能力。结果表明,制备的Pt/IrO_(x)-pH微传感器电极在pH=1.00~13.00的范围内呈现优异的线性响应性能(R^(2)=0.999);在短期(20000 s内)和长期(110 d内)均具有较高的稳定性;在溶液pH发生变化时,Pt/IrO_(x)-pH传感器电位能瞬间响应;在溶液中加入Fe^(2+)、Cu^(2+)和Cl^(-)时,线性响应不变,抗干扰能力强,但Ti^(3+)的存在会影响检测的准确性。进一步将制备的Pt/IrO_(x)-pH超微传感器电极应用于铜和304不锈钢在pH=2.00的3.5%NaCl溶液中电偶腐蚀行为研究,SECM面扫描和线扫描结果结合OCP的变化,表明Cu和304 SS在开始发生电偶腐蚀时,Cu为阴极,304不锈钢为阳极,而当浸泡至12 h时,发生阴阳极极性反转,此时Cu为阳极,而304不锈钢为阴极,且Cu表面pH更低。

The ion selective electrode technology(ISET)based on scanning electrochemical micros-copy(SECM)enables in situ monitoring of non-electrochemically active substances at both micron and submicron scales of the metal/solution interface.However,the research on the stability,potential re-sponse time,and anti-ion interference ability of ISET is obviously insufficient.In this paper,an all-solid platinum/iridium oxide(Pt/IrO_(x))electrochemical microsensor with pH response was prepared by deposing an iridium oxide thin film on the surface of a 10μm diameter platinum ultra-microelectrode.Its linear response,instantaneous potential response,stability and anti-ion interference ability were analyzed.The re-sults showed that the prepared Pt/IrO_(x)-pH microsensor electrode exhibited excellent linear response perfor-mance in the range of pH=1.00-13.00(R^(2)=0.999)and high stability in both the short term(within 20000 s)and the long term(within 110 d).When the pH value of the solution changed,the potential of the Pt/IrO_(x)-pH microsensor could change instantaneously,namely the sensor responds quickly to the solution pH value.Moreover,after adding Fe^(2+),Cu^(2+)and Cl^(-)into the solution,the linear response and stability of the sensor remain unchanged with high anti-interference ability.However,the addition of Ti^(3+)could affect the accura-cy of the microsensor detection.The prepared Pt/IrO_(x)-pH microsensor was further applied to investigate the galvanic corrosion of copper and 304 stainless steel in 3.5%NaCl solution with pH=2.00.The results of SECM surface and line scanning images combined with OCP results showed that when the galvanic corrosion of Cu and 304 stainless steel began,Cu acted as the cathode and 304 stainless steel was the anode.However,after 12 h immersion,the polarity of anode and cathode was reversed,that is,Cu was the anode and 304 stainless steel was the cathode,and the surface pH value of Cu was lower.