Enhancement of physical and chemical properties of thin film Ag/AgCl reference electrode using a Ni buffer layer

The effect of diffusion and oxidation of Ti on the physical and chemical properties of the thin film Ag/AgCl reference electrode is investigated using three different thin film structures: the Si/SiO2/Ag/AgCl, Si/SiO2/Ti/Ag/AgCl, and Si/SiO2/Ti/Ni/Ag/AgCl structures. The experimental evidences indicate that the pores on the AgCl layer are the major cause of shortening the durability of the reference electrode in a solution of high Cl- concentration. The Ni buffer layer is very effective on reducing the diffusion of Ti and O atoms into the Ag layer, results in a relatively pore free Ag/AgCl surface, and improves the physical and chemical properties of the electrode significantly. In a saturated 3.5 M KCl solution, the durability of the reference electrode with the Ni buffer layer is increased to similar to2 h, while that without the Ni buffer layer is 4-5 min. (C) 2003 Elsevier B.V. All rights reserved.