Preparation And Study Of Electrochemical Sensors For Marine Applications

21st century is the marine economy and the study on the physicochemical properties of various kinds in the ocean is of great significance for the survival and development for mankind.In situ testing which can feedback the changes in the physical and chemical parameters of the test environment timely is the focus of ocean research scholars who concerned.In this paper,several electrochemical sensors which are suitable for marine environment were prepared,with the characteristics of small size,simple operation,high sensitivity,easy to be miniaturized and can be tested in situ.The main contents related are as follows:(1)The Ir/IrO2 pH electrodes were prepared with the molten carbonate method and NaOH cyclic thermal oxidation method,respectively.A comprehensive analysis of the surface morphology,composition and performance of the electrodes prepared with different methods proved that NaOH cyclic thermal oxidation method was a more suitable preparation method for Ir/IrO2 pH electrode.In order to solve the potential drift that Ir/IrO2 pH electrode encountered for a long time,hydrothermal treatment was proposed.Experimental results showed that the treated electrode exhibited good stability,high sensitivity(70.5mV/pH),rapid response(<3s),long service life,and good reversibility with little hysteresis.The potential drift was less than 5mV in more than a month's continuous test which proved that hydrothermal treatment may be an effective way to improve the stability of Ir/IrO2 pH electrode.(2)Ag wire was used as the metal substrate,to improve the conventional preparation method,dipping silver paste method and thiacetamide(CH3CSNH2)method were proposed,from which the proper method for Ag/Ag2S H2S electrode in special circumstances of the marine environment was selected.The experimental results showed that both the electrodes prepared by these the latter two methods had the characteristics of fast response,high sensitivity,wide detection range which improved the performance of the electrode prepared by sodium sulfide method effectively.But considering the adhesion between sensitive membrane and metal matrix,the electrode preoared by thioacetamide was much more suitable for marine use.(3)In the application of simulated marine environment:Prepared the gold amalgam electrode for the detection of marine ions.And the concentration of Mn2+?Cu2+ and S2-was detected.Even when the test temperature up to 80?,there still maintained a good stripping voltammetry curve.So there was a possibility that the gold amalgam electrode had a potential to be used in higher temperature for the determination of ion.Moreover,both the prepared Ir/IrO2 pH electrode and Ag/Ag2S H2S electrode were tested in the temperature up to 150?.The results indicated that both electrodes had near-Nerstain sensitivity to the change in temperature and concentration which gave the information that the prepared electrode can be initially applied in high temperature.