A polypyrrole-mercury/mercury chloride reference electrode was initially constructed by in situ electropolymerization of pyrrole on a mercury pool anode in a 0.5 M sodium para-toluene sulfonate and 1.0 M sodium chloride mixture solution. However, in this procedure, insufficient amount of mercury was incorporated in the polypyrrole film for reaction with chloride ions to yield a mercury/mercury chloride half cell. Alternatively, a polypyrrole film was galvanostatically deposited on a glassy carbon electrode in the presence of sodium para-toluene sulfonate. Mercury was electrochemically deposited from mercury(I) nitrate at the polypyrrole-coated electrode. The resulting film was deprotonated in 5 M NaOH. Cyclic voltammetry was then carried out in 10 M HCl in order to exchange the para-toluene sulfonate ions with chloride ions and to oxidize mercury for the formation of mercury chloride within the film. A reproducible null potential difference was obtained when the polypyrrole-mercury/mercury chloride electrode was employed as an indicator electrode against a saturated calomel reference electrode in saturated potassium chloride solution.
- acid-basetreatments of polypyrrole
- polypyrrole-mercury/mercury chloride reference electrodes
- potentiometric measurements
- saturated calomel electrodes