微型金属氧化物pH电极的制备及腐蚀防护应用进展

Preparation of Micro Metal Oxide pH Electrode and Its Application in Corrosion and Protection

归纳总结了铱/氧化铱、钛基、钨/氧化钨和氧化锰pH电极的响应机理、性能参数及其研究进展。其中,铱氧化物pH电极稳定性好、响应斜率高(-59.5~-74.91 mV/pH),应用最为广泛。介绍了电化学沉积法、电化学生长法、热氧化法和溶胶-凝胶法等微型pH电极的常用制备方法,对制备方法中不同工艺参数对电极性能的影响进行分析总结。其中,电化学沉积法应用前景广阔、成本低,制备的电极响应斜率高、响应速率快,但在长期使用过程中的电位漂移问题尚待解决。针对金属pH电极的电位漂移、老化时间久等问题,阐述了水合、热处理及水热处理等后处理工艺对电极性能的改善作用及应用机制。总结了金属氧化物pH微电极在点蚀、电偶腐蚀和应力腐蚀等局部腐蚀与阴极保护方面的应用,包括使用微型金属氧化物pH电极、复合双管p H电极以及将p H电极与扫描电化学显微镜技术(SECM)相结合等应用模式。金属氧化物pH电极具有易于微型化、响应快速、性能稳定等特点,使其在监测因局部阳极腐蚀或阴极还原反应形成的金属/介质界面微区环境p H值变化的过程中表现出良好的效果。最后对微型金属氧化物pH电极制备工艺的优缺点进行了总结,并展望了其制备工艺优化及应用趋势。

Metal oxide electrode is widely used for pH examination in food,biology and medical industries due to its characteristics of wide pH response range(pH measurement range can reach 2-12,even 0-14)and easy to be miniaturized.It can be used for in situ measurement of pH value at the vicinity of metal/electrolyte interface,thus providing important parameters for deducing the possible electrochemical reactions,explaining specific corrosion behavior and revealing the relevant corrosion mechanism.In this paper,the response performance,performance parameters and the research progress of metal oxide electrodes made of iridium,manganese,titanium,tungsten and the relevant oxides were summarized.Among which,the iridium oxide electrode was most widely used as a pH detector for its stability and high response slope(-59.5--74.91 mV/pH).The commonly used preparation methods for micro metal oxide pH electrodes such as electrochemical deposition method,thermal oxidation method,sol-gel method,screen printing method,etc.as well as the effect of different process parameters were also summarized.The electrochemical deposition method had a broad application prospect,and with which the prepared electrodes had the characteristics of low cost,high response slope and fast response rate,but their potential drift for the long-term service needed to be solved.Aiming at the matter of potential drift and long aging time of metal pH electrodes,the effect of post-treatment processes such as hydration,heat treatment and hydrothermal treatment on the electrode performance were introduced.The applications of metal oxide pH micro-electrodes for the examination of pitting corrosion,galvanic corrosion,stress corrosion and other local corrosion,as well as for the monitoring cathodic protection were reviewed,including the micro metal oxide pH electrode,composite double-tube pH electrode and the combination of pH electrode and scanning electrochemical microscopy technology(SECM),etc.The metal oxide electrode was easy to be miniaturized and had a stable response,which made it show good response performance in the process of monitoring the change of pH value nearby the metal/electrolyte interface formed during local anodic corrosion or cathodic reduction reaction.Lastly,the preparation technology and application trend of the micro metal oxide electrode were also prospected.