Piezoelectric response to surface stress change of iron and copper electrodes covered with oxide films

Abstract

The piezoelectric technique combined with the admittance method has been applied to the study on iron and copper electrodes covered with oxide films in the borate buffer solutions with and without SO 4 2− ions. The addition of SO 4 2− ions enhanced the piezoelectric signal during the cathodic reduction of the oxide film on the iron electrode rather than that on the copper electrode. Similar behavior of the piezoelectric signal and the admittance were observed for the iron electrode, indicating that the cathodic reduction of the oxide films proceeds at the film/solution interface. For the copper electrode, no significant effect of SO 4 2− ions on the piezoelectric signals revealed that the solid state mechanism is operative in the cathodic reduction of oxide films. The potential of zero charge for iron and copper surfaces without any oxide films in borate buffer solution was also determined from the piezoelectric signals.