Catalysts based on carbon nanotubes modified by N, Pt, or PtCo for oxygen reaction catalysis in nonaqueous electrolyte containing lithium ions

Abstract

The effect of carbon nanotube (CNT) surface modification by oxygen– and nitrogen–containing groups on the activity of Pt–containing catalysts supported on these CNT (Pt/CNT and PtCo/CNT) studied in the oxygen reaction in aprotic electrolyte containing lithiumсations. It is shown, that modification of the CNT surface by oxygen– and nitrogen–containing groups enhances the polarization capacity of the material that characterizes the value of the electrochemically active surface area and lowers the overpotential of the oxygen reduction reaction (ORR). Synthesis of platinum or its alloy (PtCo) on modified CNT allowed establishing the relationship between the activity of these catalysts in the oxygen reaction in aprotic electrolyte and the synthesis conditions and CNT pretreatment. The catalytic effect of modification by platinum consists in a decrease in the ORR overpotential with formation of Li2O2 and its further anodic decomposition and in an increase in the reversibility degree. It is shown that the sites on which Pt nanoparticles are fixed on the CNT surface are oxygen–containing groups. The most probable result of synthesis of PtCo alloy on CNT is the binding of cobalt to nitrogen in nitrogen–containing groups and then to platinum (N–Co–Pt).