Preparation And Performance Testing Of Low-noise Ag/AgCl Electrodes Suitable For Deep-sea

All-solid-state Ag/AgCl electrodes are the most widely used electrodes with unique advantages in the detection of submarine electric fields.The performance of Ag/AgCl electrode is related to the composition,structure and microscopic morphology of the internal raw materials of the electrode.All-solid-state Ag/AgCl electrodes may have problems such as insufficient stabilization time of electrode potential and high noise in actual marine testing.Aiming at these problems,the optimization research was carried out from the aspects of the preparation of precursor powder,the process parameters of electrode preparation,and the composition and structure of electrode.Firstly,the raw material AgCl powder is prepared by two methods:thermal drying and freeze drying.The experimental characterization and comparative analysis of the powders showed that the AgCl powder particles treated by freeze-drying were more fluffy,smaller in particle size,lower in ionized water content and better in dispersibility.To analyze the phase,microstructure and pore distribution of the electrodes,the electrodes prepared under different molding pressures were analyzed by means of scanning electron microscopy(SEM),immersion medium method.The polarization properties of the electrodes were tested by an electrochemical workstation and the exchange current densities of different electrodes were obtained.The self-noise and potential stability results showed that the preparation process of the electrode changed the micro-structures of the electrodes and had significant influences on the electrochemical performance and macroscopic test performance of the electrode.Within the range of forming pressure(3 MPa-4.5 MPa),the higher the forming pressure was,the lower the porosity of the electrode was.Meanwhile both the effective area for reaction and the exchange current density increased.On the contrary,the degree of electrochemical polarization decreases.The comprehensive performance of the electrode is the best when the forming pressure of the electrode reached 4.5 MPa,the electrode noise level can reach below 5 nv/?Hz,and the24-hour stability of the electrode potential was the best.The electrode potential stabilization time was shortened,and the range potential was below 0.05 m V.When the forming pressure reached 5 MPa,the electrode body was damaged occasionally because of the higher forming pressure.And the performance of these electrodes,fabricated under 5 MPa,was weaker than those that were prepared under 4.5 MPa forming pressure.The graphene/Ag nanocomposites were prepared and added to modify the traditional Ag/AgCl electrode.The experimental results showed that the ratio of Ag NO₃to graphene stayed 7:2 was relatively good in graphene effective loading of Ag nanoparticles,and the material performance was better.Addition of the graphene could effectively improve the granulation process and sintering process,and the specific surface reaction area.The addition of graphene enhanced the physical and mechanical strength of the electrode and improves the thermal conductivity during the electrode sintering process.After modification,the electrode range potential became smaller,the stabilization time of electrode potential was shortened,and the noise level was reduced,of which the the lowest noise level could reach about 5 n V.Preparation of low-noise Ag/AgCl electrodes that meet the requirements of detection performance through process optimization and modification.