Carbon Nanotubes Modified with Oxygen- and Nitrogen-Containing Groups as Perspective Catalysts for the Oxygen Electroreduction Reaction

Oxygen electroreduction is the key reaction among processes and devices of practical importance. Accordingly, the efforts of researchers are directed to the development of catalysts for the oxygen reduction reaction, which provided the effective oxygen reduction and stability at their low cost. Carbon nanotubes modified with oxygen- and nitrogen-containing groups, under the oxygen/nitrogen ratio of 1.3, meet these requirements considerably. In this work, we show that carbon nanotubes modified by oxygen and nitrogen accelerate the oxygen reduction reaction both in acid and alkaline electrolytes. Here, the modifying of carbon nanotubes' surface increased the electrochemical activity in the oxygen reduction reaction significantly which manifests itself in the shift of the half-wave potential in polarization curves in acid electrolyte by similar to 0.40 V to more positive values in comparison with not modified carbon nanotubes (in acid electrolyte). In alkaline electrolyte, the modified carbon nanotubes approach monoplatinum catalyst in their activity in the oxygen reduction reaction. The stability of modified carbon nanotubes (according to the testing by the potential cycling) is superior to that of the untreated carbon nanotubes. The obtained data show the perspectives of the modified carbon nanotubes' application as supports for cathodic catalysts of low-temperature hydrogen-air fuel cells. In the direct alkaline alcohol-air fuel cells and metal-air power sources of lithium-air type, the modified carbon nanotubes can be used as catalysts per se. The tailor-made synthesis of desired type and amount of nitrogen-containing groups is suggested to be realizable after the preliminary modification of carbon nanotubes with the oxygen-containing groups.