Abstract: The anions of Dawson-type tungstophosphate acid were modified on the surface of a carbon paste electrode by the sol-gel technique. The electrochemical behavior of the modified electrode was studied in detail, including pHdependence, stability and so on. Experimental results show that the modified electrode not only maintains the electrochemical activity and electrocatalytic properties of P₂W₁₈, but also has a good stability and sensibility. In 0.5 mol/L H₂SO₄ solution, the third and the fourth cathodic peaks of P₂W₁₈ doped in sol-gel film have a good catalytic effect on the reduction of nitrite. The catalytic current is proportional to NO₂^-concentration. At the same time, we found that the third and the fourth cathodic peaks of P₂W₁₈ doped in sol-gel film had an excellent effect on the reduction of dioxygen.

Key words: Sol-gel technique, 2∶18 Tungstophosphate acid, Electrocatalysis, Nitrite ions, Dioxygen