Electrochemical properties of titanium-based catalytically active electrodes in perchloric acid
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ELECTROCHEMICAL PROPERTIES OF TITANIUM-BASED CATALYTICALLY ACTIVE ELECTRODES IN PERCHLORIC ACID О. V. Kosohin,1, 2 A. І. Kushmyruk,1 Yu. S. Miroshnychenko,1 and O. V. Linyucheva1 The electrochemical behavior of the electrodes made of titanium powders and catalytically active materials based on titanium in solutions of perchloric acid is studied by the voltammetry methods. The influence of preliminary preparation of titanium on its electrochemical behavior is investigated with an aim to develop new modes of treatment of titanium used as the base material for the gas-diffusion electrodes of electrochemical sensors. It is shown that, titanium may play the role of conductive base for catalytically active materials in HClO 4 solutions within the potential range 0.5–1.7 V. The accumulated results show that there exists a range of values of the working potentials of titanium-based electrodes attained in air within which the analyzed components can be detected with high resolution. Depending on the nature of catalytically active materials, the range of working potential lies between 100 mV for the Ti/MnO 2 electrode and almost 400 mV for the Ti/Pt electrode inside the range of values of the stationary currentless potential of the working electrode determined in air. Keywords: electrochemical sensors, monitoring of air, matrix electrolyte, perchloric acid, titanium, oxidation, catalytically active electrode.
The world park of gas-analyzing equipment intended for the monitoring of the ecological safety of air is, for the most part, based on amperometric electrochemical sensors [1, 2]. A new generation of electrolytic sensors used in portable and stationary gas analyzers and multichannel gas-analyzing systems for the monitoring of air was created on the basis of matrix and solid proton electrolytes and framed catalytically active gas-diffusion electrodes [3, 4]. Titanium powders are used as the corrosion-resistant conducting base of gas-diffusion matrices and catalytically active electrodes of these sensors [5]. However, the data on the electrochemical behavior of titanium powders in solutions of perchloric acid are practically absent and the results available from the literature were obtained solely for the compact metal [6–8]. Thus, it is necessary to perform the detailed investigation of the mechanisms of corrosion processes running on the surface of titanium in order to predict its behavior in the case of its application as the inert conducting base in portable sensor systems operating under the conditions of variations of the pH values of electrolyte solutions and the activity of water in these solutions under the action of atmospheric conditions.
Experimental Procedure We used PТEМ titanium powder with grain sizes within the range 0.05–0.10 mm and a specific surface area of ∼ 0.2 m 2 /g determined by the BET (Brunauer–Emmett–Teller) method. 1 2
“Kyiv Polytechnic Institute” National Technical University, Kyiv, Ukraine. Corresponding author; e-mail: [email protected].
Translated from Fizyko-Khimichna Mekhanika Materialiv
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