The study of PVP/Pd/IrO₂ modified sensor for amperometric determination of sulfur dioxide

A novel electrochemical sensor for the detection of sulfur dioxide in both gas and solution is described. The chemically modified electrode was constructed by polymerizing (4-VP), palladium and iridium oxide (PVP/Pd/IrO₂) onto a platinum microelectrode which exhibits excellent catalytic activity toward sulfite with an oxidation potential of + 0.50 V. The SO₂ gas sensor is based on the PVP/Pd/IrO₂ modified electrode as working electrode, Ag/AgCl electrode as reference electrode, Pt electrode as counter electrode and a porous film, which is in direct contact with the gas-containing atmosphere. The effect of different internal electrolyte solutions of hydrochloric acid, sulfuric acid, phosphates buffer solution, mixed solution of dimethyl sulfoxide and sulfuric acid to the determination of SO₂ was also studied. The sensor was found to have a high current sensitivity, a short response time and a good reproducibility for the detection of SO₂. It has good potential to be used in the field of environmental monitoring and controlling.