Electrocatalytic Activity of Sodium Copper Pectates in Oxygen Reduction Reaction in Fuel Cells

Abstract

In this paper, the results of the electrocatalytic behavior of a series of copper sodium pectate complexes with different Cu2+ contents (5, 10, 15, 20, 25%) towards the oxygen reduction reaction (ORR) are presented. To investigate the catalytic activity of the studied complexes in ORR, the cyclic voltammograms (CVA) recorded in an oxygen-saturated environment and inert argon gas were compared. Clear reduction peaks are observed in the CVA, confirming the electrochemical activity of the complexes in the oxygen reduction reaction. The kinetics and mechanism of the oxygen reduction reaction on the glassy carbon modified with the complexes in an acidic 0.5 M H2SO4 medium were analyzed. The results obtained by cyclic voltammetry at different scan rates show that the ORR on the copper sodium pectate complexes supported on the glassy carbon is diffusion-controlled. The calculation of the number of electrons participating in the electrochemical reaction was carried out. It was found that the best catalyst of the entire series of samples is a sodium pectate complex with a 5% copper content (n = 4). It was noted that the compound is characterized by a large specific surface area. An increase in the amount of copper ions in coordination biopolymers leads to film formation and a decrease in catalytic activity.