Preparation and H+ response mechanism of W/WO3 pH electrode by sol-gel method
(1. School of Science, Foshan University, Foshan 528000, China;
2. Department of Chemistry, Huazhong University of Science and Technology,
Wuhan 430074, China)
2. Department of Chemistry, Huazhong University of Science and Technology,
Wuhan 430074, China)
Abstract: A method of sol-gel for preparing a W/WO3 pH electrode was presented. H+ response characteristics, such as response range, response sensitivity, response time were investigated. The effect of heat-treatment on response linear relation was discussed. The influences of interfered ions and solution temperatures were also taken into consideration. Many kinds of determination technology, such as TG, DSC, IR, SEM, AFM,XPS, XRD were used to characterize the film. The results show that the film appears in crack dried-mud, and the film is composed of WO3, WO3•H2O or WO3•0.33H2O; the hydrate water decreases with the increase of the heat-treatment temperature; the W+6 in the electrode film transfers to W+5 in the course of H+ response; the H+ response course is controlled by the H+ diffusion from the solution to the WO3 crystalline, which is indicated in the EIS spectra; the best heat-treatment temperature is 200℃, and at this temperature, the electrode has an H+ response sensitivity of 52mV/pH.
Key words: sol-gel; W/WO3; pH electrode; film composition; H+ respouse mechanism