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通电电流密度及极化时间对Ag/AgCl电极性能影响较大,其取值争议较大。将Ag棒放入0.1 mol/L的HCl溶液中进行电解,电流密度为0.5,1.0,2.0,3.0,4.0 m A/cm~2,通电时间为0.5,1.0,1.5,2.0,2.5,3.0 h。在电极电解过程中,记录电位-时间曲线。通过SEM观察不同条件所得电极的表面形貌,并用EDS分析其元素组成。结果表明:随着极化时间的增长,Ag棒表面电解产物增多,在恒定通电电流密度条件下,电解产物的生成增大了电极的电阻,从而导致电极电位随极化时间的增长而增大;极化时间相同时,通电电流密度越大,电解产物生成速度越快,电极电位越高,多层电解产物的穿插生成导致电极表面粗糙,并伴有小坑等缺陷出现;电解产物主要由Ag和Cl组成;当电流密度小于或等于1.0 m A/cm~2时,电极电位增长缓慢,电解产物缓慢生长,电极表面较为致密,通电电流密度为0.5 m A/cm~2的电极电位在9 800 s左右出现骤降,为获得较为致密和性能稳定的Ag/AgCl电极,建议阳极极化法制备Ag/AgCl电极的通电电流密度为0.5 m A/cm~2,极化时间为2.5 h(9 000 s)。
The current density and polarization time have a great influence on the performance of Ag / AgCl electrode, which is controversial. Ag rod into 0.1 mol / L HCl solution for electrolysis, the current density of 0.5,1.0,2.0,3.0,4.0 m A / cm ~ 2, the power time of 0.5,1.0,1.5,2.0,2.5,3.0 h . During the electrode electrolysis, the potential-time curve is recorded. The surface morphology of the electrode obtained under different conditions was observed by SEM, and its elemental composition was analyzed by EDS. The results show that with the increase of polarization time, the electrolysis products on the surface of Ag rod increase. Under constant current density, the formation of electrolysis products increases the resistance of the electrode, which leads to the increase of electrode potential with the increase of polarization time ; The same polarization time, the higher the current density, the faster the rate of electrolysis products, the higher the electrode potential, the formation of multi-layer electrolysis products lead to electrode surface roughness, accompanied by pits and other defects appear; electrolytic products mainly by Ag and Cl. When the current density is less than or equal to 1.0 m A / cm ~ 2, the electrode potential increases slowly, the electrolysis product grows slowly, and the electrode surface is dense. The electrode current with current density of 0.5 m A / cm ~ In order to obtain a more compact and stable Ag / AgCl electrode, it is suggested that the current density of Ag / AgCl electrode prepared by anodic polarization is 0.5 m A / cm ~ 2 and the polarization time is 2.5 h (9 000 s).