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Sensing mechanism of RuO2–SnO2 thick film pH sensors studied by potentiometric method and electrochemical impedance spectroscopy

Manjakkal, Libu; Cvejin, Katarina; Kulawik, Jan; Zaraska, Krzysztof; Szwagierczak, Dorota; Stojanovic, Goran


Katarina Cvejin

Jan Kulawik

Krzysztof Zaraska

Dorota Szwagierczak

Goran Stojanovic


In this work, we developed thick film pH sensors based on the nanostructured RuO2–SnO2 system and analyzed their sensing mechanism using the potentiometric and electrochemical impedance spectroscopic (EIS) methods. The crystal structure and morphology of the sensitive films were investigated by X-ray diffractometry, Raman spectroscopy, scanning electron microscopy and energy dispersive spectroscopy. The potentiometric sensor exhibits Nernstian behavior (56.5 mV/pH) in the pH range of 2–12. It shows very fast response (5 s and 9 s, for acidic to basic and basic to acidic solutions), long lifetime, small hysteresis effect, and good reproducibility. Selectivity test proved that the presence of Li+, Na+, and K+ ions in a solution had no significant influence on the sensor performance. Conductance, capacitance and impedance of the conductimetric pH sensor with the interdigitated electrode were found to vary with changing pH and as a function of the applied frequency in the range of 10 Hz–2 MHz. The EIS analysis of the complex impedance data by using Nyquist and Bode plots revealed the information about the underlying processes, like adsorption, diffusion and charge transfer, occurring at the metal oxide-solution interface. The proposed thick film pH sensors were intended to be used for water pollution monitoring.


Manjakkal, L., Cvejin, K., Kulawik, J., Zaraska, K., Szwagierczak, D., & Stojanovic, G. (2015). Sensing mechanism of RuO2–SnO2 thick film pH sensors studied by potentiometric method and electrochemical impedance spectroscopy. Journal of Electroanalytical Chemistry, 759, 82-90.

Journal Article Type Article
Acceptance Date Oct 29, 2015
Online Publication Date Dec 12, 2015
Publication Date 2015-12
Deposit Date Jul 20, 2022
Journal Journal of Electroanalytical Chemistry
Print ISSN 1572-6657
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 759
Pages 82-90
Keywords Electrochemistry; General Chemical Engineering; Analytical Chemistry
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