Mercury-coated platinum microelectrodes for steady-state voltammetry in aqueous solutions at high temperature

Sphere-cap mercury microelectrodes fabricated on a platinum disk substrate were tested in aqueous solutions over the temperature range 295-353 K. The performance of these electrodes was assessed in solutions containing Ru(NH3 )(6)Cl-3 and LiClO4 as supporting electrolyte. From the steady-state limiti ng current obtained at three different mercury microelectrodes, the diffusi on coefficient of the electroactive species at different temperatures was d etermined. It was found that the diffusion coefficient values were consiste nt with the Stokes-Einstein and activation energy models. The results obtai ned also allowed us to conclude that sphere-cap mercury microelectrodes can be useful for elevated temperature electroanalysis in aqueous solutions. ( C) 2000 Elsevier Science S.A. All rights reserved.