Physico-Chemical nanomaterials science

The peculiarities of point-contact nanostructure  
behavior in ion-conducting media 
 
O.P. Pospelov1, G.V. Kamarchuk2 , A.O. Herus2 , M.D. Sakhnenko1, M.V. Ved1,  V. Vakula2 
 
1 Department of Physical Chemistry, National Technical University “Kharkiv Polytechnic Institute”. 
2 Kyrpychov Str., Kharkiv, 61002, Ukraine. 
2 Department of Spectroscopy of Molecular Systems and Nanostructured Materials, B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine. 
47 Nauky Ave., Kharkiv, 61103, Ukraine. 
E-mail: gerus@ilt.kharkov.ua 
  
The investigations of the last years have evidenced that Yanson point contact [1] in an ion-conducting media can be considered as a nanostructured electrochemical gapless electrode system (GES) [2, 3]. One of the characteristic peculiarities of the GES behaviour is charge transfer in two parallel branches that corresponds to electron and ion conduction channels. The electron channel is realized in the bulk of the conductor and provides for direct electric conductivity. The ion channel is localized in electrolyte along the “metal-electrolyte” interface. The transfer processes in these channels are pair conjugated that stimulates a set of original physical-chemical effects and transformations. One of the most interesting results of such interaction is the cyclic switchover effect [2]. The cyclic switchover effect is a basis for a new operating principle of selective detection realized in the innovative sensitive transducers for analysis in liquid and gas media [3]. 
In our work in the framework of the GES concept the model of the process of anode destruction of the copper Yanson point contact has been considered under the cyclic switchover effect. It was shown that the conduction channel’s surface of the dendritic Yanson point contact demonstrates enhanced electrochemical activity. It can be explained by the dimensional effect and existence of the fresh synthesized bulk metal phase on the phase boundary. The obtained results create prerequisites for performance improvement of the new type of quantum sensor devices. 
This work was partly supported by the NATO SPS Programme (Ref: SPS 985481) and the NAS of Ukraine.   
  
1. G.V. Kamarchuk, A.P. Pospelov, L.V. Kamarchuk, and I.G. Kushch, “Point-contact sensors and their medical applications for breath analysis: a review”, in Nanobiophysics: Fundamentals and Applications, V.A. Karachevtsev, ed. (Pan Stanford Publishing Pte. Ltd., 2015) Chap. 11, 327-379. 
2. A.P. Pospelov, A.I. Pilipenko, G.V. Kamarchuk, V.V. Fisun, I.K. Yanson, E. Faulques, A new method for controlling the quantized growth of dendritic nanoscale point contacts via switchover and shell effects. J. Phys. Chem. C  119, 632-639 (2015). 
3. G.V. Kamarchuk, A.P. Pospelov, A.V. Savytskyi, A.O. Herus, Yu.S. Doronin, V.L. Vakula,  E. Faulques, “Conductance quantization as a new selective sensing mechanism in dendritic point contacts”, SN Applied Sciences  1:244 (2019).