Naslov
Thin oxide film on indium: Impedance spectroscopy investigation of reductive decomposition

Autori
Omanović, Saša ; Metikoš-Huković, Mirjana

Izvornik
Thin solid films (0040-6090) 266 (1995), 1; 31-37

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
indium oxide films ; reductive decomposition ; electrochemical impedance spectroscopy

Sažetak
The kinetics of cathodic reduction of an In2O3 film grown on a bare indium substrate under dynamic conditions was studied by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) in borate buffer, pH 10. Reductive decomposition of In2O3 up to metallic In proceeds in the solid phase, via a solid-state mechanism: In2SO3(s) + 2H2O(aq) + 6e− ↔ 2In(s) + 6OH−(aq). Impedance spectra obtained between 40 mHz and 50 kHz, in the potential range of oxide film stability, its decomposition, new metal phase extraction and hydrogen evolution were interpreted on the basis of equivalent electrical circuits using a suitable fitting procedure. EIS has shown to be a valuable tool in the characterization of the solid/liquid interface: (i) the passive In2O3 film behaved as a simple dielectric, the interface of a passive electrode was blocking and in Bode and Nyquist plots a capacitive feature appeared ; whereas (ii) in the vicinity of the In/In2O3 redox potential a Warburg low-frequency feature was obtained, which was associated with diffusion processes in the solid phase as the rate-determining step ; (iii) the interface of the freshly segregated metallic phase was a close-to-perfect RC feature, which was associated with charge transfer as the rds for the hydrogen evolution reaction on the bare metal surface. Cyclic voltammetry has revealed more details of the reduction processes giving further insight into the mechanism of reductive decomposition of In2O3 up to metallic In.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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