Influence of the Oxidized Carbon Nanotubes Modification Conditions on Their Catalytic Activity and Selectivity in the Oxygen Reduction Reaction to Hydrogen Peroxide

Abstract

Catalysts of the hydrogen peroxide cathodic synthesis are obtained from multiwalled carbon nanotubes pre-oxidized with nitric acid, follow by hydrogen reduction in the 300–500°C temperature range. Evaluation of physico-chemical properties of the catalysts showed the synthesis method used to be able controlling changes in the surface oxygen groups’ composition without any change in the multiwalled carbon nanotubes’ structure and morphology. Investigation of catalytic activity in the cathodic process for hydrogen peroxide production demonstrated the sample prepared by hydrogen reduction at 300°C with oxygen content of 5.2 at % (according to XPS data) to have the highest efficiency. The sample produced the hydrogen peroxide with the rate of 0.34 mol/(g h) and Faradaic efficiency of 78%. Increase in the reduction temperature above 300°C resulted in a decrease in the rate of Н₂О₂ accumulation without severe changes in Faradaic efficiency.