ELECTROCHEMISTRY OF NICKEL COMPLEXES WITH SODIUM PECTATE WHILE REDUCING ON GOLD, PLATINUM AND GLASS-CARBON ELECTRODES IN PRESENCE OF CO<sub>2</sub>
Searching for new ways of converting carbon dioxide into value-added products, such as fuels, is a relevant task of our time. Electrochemical reduction of carbon dioxide to carbon monoxide, hydrocarbons, alcohols, and formates is considered as one of the main approaches in this area. One of the most advanced approaches is the use of coordination polymers, particularly scaffold structures, for homogeneous and heterogeneous catalysis of carbon dioxide reduction. In this paper, we are proposing pectic coordination polymers with nickel (PG-NaNi) as a choice for the promising catalysts of carbon dioxide reduction. Nickel - sodium pectate complexes are the components of the coordination polymer and have additional advantages as compared to those of the majority of the known catalysts of carbon dioxide reduction. First, they are cheap and easily available, since one of the core initial reacting agents in their synthesis is pectin, i.e., the product obtained from treating omnipresent biological waste. We have obtained coordination pectin polymers with different contents of nickel ions. Contents of sodium and nickel ions in the compounds obtained were found using atomic emission spectroscopy. The state of carboxyl groups was controlled using IR spectroscopy. Using the cyclic voltammetry method, we have shown that a catalytic response is observed regarding the carbon dioxide reduction reaction, when saturating the colloid aqueous solution of the obtained compounds with carbon dioxide and reducing them on gold and glass-carbon electrodes. We have also found the decreasing currents of current-voltage characteristics on all the electrodes used when reducing the solutions of the compounds in presence of CO2. This occurs due to precipitating the reaction products on the electrodes and, therefore, reducing its active area.