The Effect of Electrochemical Modification of the Glass Carbon Surface in Conditions of Chemisorption of Fluorine-Contai
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The Effect of Electrochemical Modification of the Glass Carbon Surface in Conditions of Chemisorption of Fluorine-Containing Nanogroups on its Electrophysical Properties Yulia M. Stryuchkova, Sergey M. Karabanov, Dmitriy V. Suvorov, Evgeniy V. Slivkin, Gennadiy P. Gololobov and Dmitry Yu. Tarabrin Ryazan State Radio Engineering University, 59/1 Gagarina St., Ryazan 390005, Russia ABSTRACT The electrophysical (donor-acceptor) properties of the of glass carbon (GC) surface before and after its electrochemical modification in conditions of chemisorption of fluorinecontaining nanogroups were studied using the methods of scanning probe microscopy. The values of the coefficients characterizing local (for atomic-scale) electrophysical properties of the surface are calculated on the basis of obtained local spectral dependences of the tunneling current on the tunnelling voltage. Fluorination of the GC surface resulted in change of the ratio of its donor-acceptor atomic characteristics, acceleration of electrode processes, and increase of the overall tunneling activity of local places. INTRODUCTION Glass carbon (GC) is characterized by unique properties: high mechanical strength, chemical and electrochemical inertness, gas-tightness, good electrical conductivity, etc. That is why GC is widely used in different industry fields. Its use as an electrode material in galvanic cells is well known. GC electrodes are characterized by high catalytic activity and resistance. The catalytic properties of the material, including glass carbon, depend on its surface properties (the ratio of the donor and acceptor properties of the surface atoms). To modify the surface properties, various treatments are used, including electrochemical treatment. So, it is interesting to clarify the reasons for having such characteristics. There are some works in which such properties are explained by changing the nanostructure of the GC electrode surface during its operation. It happens as a result of modifying effects on the surface under electrolysis conditions. Such changes include, e.g., the occurrence of functionally active surface components with nanoscale chemisorption groups [1-3]. At present, a wide variety of methods for studying the surface of various materials is known. Scanning tunneling microscopy (STM) and scanning tunnel spectroscopy (STS) make it possible to obtain information on the surface state for atomic-scale. Additional information about the local atomic properties of the surface can be obtained by scanning tunnel voltage spectroscopy (STVS), which efficiency in case of some metals and alloys has already shown [4,5]. The application of this method is based on the analysis of the STVS data. On individual surface atoms, spectra characterizing the dependence of the tunneling current (It) on the tunnel voltage (Ut) are obtained. The formula adequately describing such spectra was derived empirically [5].
U 1 U t I t G0 exp t exp The parameters the formula includes have an obvious physic
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