7 research outputs found
Perklorátionok redukciĂłjának vizsgálata ĂgĂ©retes elektrokatalitikus tulajdonságokkal rendelkezĹ‘ fĂ©meken = Investigation of the reduction of perchlorate ions on metals of promising electrocatalytical properties
Jelen kutatás során voltammetriás, impedanciaspektroszkĂłpiai Ă©s bending beam mĂ©rĂ©seket vĂ©geztĂĽnk rĂłdiumon Ă©s rutĂ©niumon perklorátionokat tartalmazĂł közegben. KĂsĂ©rleteink során kĂĽlönbözĹ‘ mĂłdon előállĂtott mintákkal dolgoztunk: tömbfázisĂş fĂ©mekkel, arany hordozĂłra leválasztott illetve vákuumpárologtatott rĂ©tegekkel. MindkĂ©t fĂ©m Ă©s mindegyik előállĂtási mĂłd esetĂ©n tapasztaltuk a perklorátionok redukciĂłját. A redukciĂł mĂ©rtĂ©ke fĂĽggött a felĂĽlet Ă©rdessĂ©gĂ©tĹ‘l, az aktĂv helyek számátĂłl Ă©s a hĹ‘mĂ©rsĂ©klettĹ‘l. RĂ©szletesen vizsgáltuk a redukciĂł termĂ©kekĂ©nt keletkezĹ‘ kloridionok hatását a folyamatra. FelmerĂĽlt annak lehetĹ‘sĂ©ge, hogy a perklorátionok redukciĂłja fĂ©m/vezetĹ‘ polimer (pl. PEDOT (poli(3,4-etilĂ©ndioxitiofĂ©n))) kompozitokban is lejátszĂłdik, ezĂ©rt kezdeti lĂ©pĂ©skĂ©nt megvizsgáltuk a polimer stabilitását. Tapasztalataink szerint a PEDOT kellĹ‘en pozitĂv potenciálokon tĂşloxidálĂłdik, közben elektrokĂ©miai-mechanikai tulajdonságai megváltoznak. Ezen vizsgálatokkal párhuzamosan a laboratĂłriumban kifejlesztĂ©sre kerĂĽlt egy olyan mĂ©rĂ©si mĂłdszer, mely lehetĹ‘vĂ© teszi, hogy a hagyományos forgĂłgyűrűs korongelektrĂłddal vĂ©gzett mĂ©rĂ©sekkel szemben mindkĂ©t munkaelektrĂłd potenciálját folyamatosan változtathassuk egymástĂłl fĂĽggetlenĂĽl, s a korongon zajlĂł folyamatrĂłl mĂ©g több informáciĂłt nyerhessĂĽnk. Az Ăşj rendszerrel várhatĂłan mind a polimerek stabilitásárĂłl, mind a perklorát redukciĂł rĂ©szleteirĹ‘l hasznos informáciĂłk nyerhetĹ‘k a jövĹ‘ben. | In the present work voltammetric, impedance spectroscopic and bending beam measurements were carried out on rhodium and ruthenium in perchlorate containing media. Different samples were used: bulk phase metals, electrochemically deposited and evaporated layers. The perchlorate ions can be reduced on both metals and all type of samples. The rate of the reduction depends on the surface roughness, the number of the active sites and on the temperature. The effect of the chloride ions produced in the reduction process has been investigated in details. Possibility of the reduction of perchlorate ions has raised in metal/conducting polymer (e.g. PEDOT (poly(3,4-ethylenedioxythiophene))) composites, therefore as a first step the stability of the polymer has been studied. During the overoxidation of the PEDOT film its mechanical and electrochemical properties change. Parallel to these investigations, new rotating ring-disc electrode methods have also been developed in our laboratory. With the aid of the new system, independent and dynamic potential programs can be applied simultaneously to the disk and the ring electrodes. This „dual cyclic voltammetry” is a promising method for studying the stability of polymers or the mechanism of the perchlorate reduction
Interpretation of certain features of the interface stress vs. electrode potential curves of gold with the help of dual dynamic voltammetry
It is a widespread opinion that the electrochemical behavior of gold in aqueous media has been thoroughly studied, and the interface stress changes of gold can be explained by monolayer oxide formation/removal and adsorption phenomena. However, in spite of the voluminous literature on this subject, an understanding of these systems and processes is far from complete. The combination of in-situ interface stress measurements and dual dynamic voltammetry brings new insights into the complexity of such systems. One remarkable result is that in the oxide reduction region of gold in sulfuric acid solutions a sudden change in the slope of the interface stress vs. electrode potential curve recorded during the negative-going scan of the cyclic voltammogram can be observed. By applying the dual dynamic voltammetric method to a gold/gold rotating ring-disk electrode (RRDE) it could be shown that the sharp change in the slope of the surface stress vs. potential curve recorded in the oxide reduction region of gold in sulfuric acid solutions is accompanied by the formation of soluble, electrochemically reducible gold species which can be detected at the ring electrode. © The Electrochemical Society
Experimental methods for the determination of stress changes at electrified solid-liquid interfaces
Abstract
In the present study some of the methods developed for the
experimental determination of (interfacial or film) stress changes in
electrochemical systems containing solid-liquid interfaces are briefly
reviewed, as well as the kind and quality of information that can be
obtained using these methods are discussed. The “bending beam”
(“bending cantilever”, “laser beam deflection”, “wafer
curvature”) method and related techniques, the piezoelectric method,
the extensometer method, and the method based on the measurement of
contact angle are discussed in detail. Special attention has been paid
to problems related to the use of optical methods for position
sensing.</jats:p