Abstract:

A tungsten oxide pH electrode was first prepared by means of sol-gel method.Modified KCI-doped poly-vinyl alcohol and Nation film were next coated on anode·polarized Ag wire to obtain a solid Ag/AgCI reference elec-trode.Then,a tungsten oxide pH sensor without the inner solution and the ceramic plug was fabricated with the prepared pH electrode and the solid reference electrode.Tested results indicate that the prepared pH sensor possesses
a good voltage(V)-pH response linearity in the pH range of 2-1 1,with a response sensitivity of 52.6 mV(the voltage variation per unit pH value)and a measurement accuracy of 0.1 unit of pH value,and that the tungsten oxide pH electrode resists the corrosion of HF,with a perspective of the response voltage when being applied to the HF solution with a mass fraction of 5%-20%.meaning that the electrode adapts to the concentration determination
of HF solution.Moreover.the pH sensor works very well in sol solution,with a response time less than 1 min.

Key words: sensor, tungsten oxide, pH value, electrode