Effect of Liquid-Phase Oxidative Treatments on the Purity, Hydrophilicity, and Structure of Single-Wall Carbon Nanotubes and on the Electrical Conductivity of Their Arrays

A study using a set of physicochemical methods has shown that treatment of single-wall carbon nanotubes synthesized by the electric arc method with an aqueous solution of hydrogen peroxide (followed by treatment with hydrochloric acid) and with a mixture of concentrated nitric and sulfuric acids leads to a decrease in the content of inorganic impurities in the bulk of the finished materials. The acid oxidizing mixture shows the highest performance in the process, causing splitting of the bundles of single-wall carbon nanotubes into separate nanotubes and formation of stable concentrated suspensions of the nanotubes in water and in an isopropanol–water mixture. Both kinds of liquid-phase oxidative treatment enhance the electrical conductivity of the nanotube arrays and exert no pronounced selective effect on single-walled carbon nanotubes depending on the electronic conductivity of molecules of this material.