ЕЛЕКТРОКАТАЛІТИЧНЕ ВИДІЛЕННЯ ВОДНЮ НА СУПЕРСПЛАВАХ CoRe, CoWRe, ОСАДЖЕНИХ ІЗ ЦИТРАТНОГО ЕЛЕКТРОЛІТУ

• Date: 2020
• Main Authors: Yapontseva, Yuliya, Maltseva, Tetiana, Kublanovsky, Valeriy
• Format: Article
• Language: English
• Published: V.I.Vernadsky Institute of General and Inorganic Chemistry 2020
• Online Access: https://ucj.org.ua/index.php/journal/article/view/232
• Journal Title: Ukrainian Chemistry Journal

Chemical composition and electrocatalytic properties of binary (CoRe) and ternary (CoWRe) alloys electrodeposited from citrate electrolyte with different amount of potassium perrhenate (0.01 and 0.05 mol·L-1) depending on the deposition current density (5÷40 mA·cm-2) are shown. It was found that rhenium, which is practically not reduced at the cathode to the metal from an individual solution, in the formation of an electrolytic alloy with cobalt is able to be reduced in large quantities (44-67 at.%); in the formation of ternary alloys there is a decrease in the amount of rhenium in the alloy (15-41 at.%) at a tungsten content of 4-5 at.%, which is almost unchanged at all values ​​of the deposition current density. The reaction of hydrogen ions electroreduction on the obtained coatings was studied by the method of stationary voltammetry. The kinetic parameters of the reaction (coefficients of the Tafel equation, logarithm of the hydrogen exchange current density and overvoltage at the selected current density of 10 mA·cm-2) are calculated and it is shown that the best electrocatalysts for hydrogen electroreduction in alkaline solution can be ternary alloys CoWRe with rhenium content 15-20 at. %, which allow to increase almost by an order of magnitude the exchange current density and significantly reduce hydrogen overvoltage (150-170 mV) compared to cobalt. The presence of a small number of refractory metal atoms allows obtaining such a distribution of elements on the surface that provides surface diffusion of hydrogen atoms from the rhenium or tungsten atom, where the first electron transfer are quickly (Volmer reaction), to the cobalt atom, on which electrochemical desorption takes place (Heyrovsky reaction). The increase in the content of refractory metals leads to a decrease in the electrocatalytic effect.