MWCNTs produced by electrolysis of molten carbonate: Characteristics of the cathodic products grown on galvanized steel and nickel chrome electrodes

Electrolytic synthesis in molten salts has excellent possibilities for the production of various carbonaceous materials, nevertheless, a study of the synthesis conditions is necessary for that the carbon products obtained is in the carbon nanotube (CNT) structure. In this work, the possibility of production of MWCNTs (multi walled carbon nanotubes) by the electrolytic synthesis of molten salts has been shown. The product structure and morphology can be controlled by choosing the right electrolysis conditions (type of electrode, applied current and electrolysis time). The properties of the produced carbon-containing products were analyzed by XRD, TEM, HRTEM and Raman spectroscopy. A correlation of product properties with synthesis conditions and parameters has been made. When using steel and nickel chrome as cathode, the products have lower levels of defects and are partially filled with metal phase when 1 A and 4 h of electrolytic synthesis were used. The metal phase acts as a catalyst for the nanotubes generation in the electrolytic synthesis from molten salts. Even so, after electrolysis for 4 h, these products are 90% MWCNT. The MWCNT growth on the galvanized steel or nickel-chrome cathodes is similar to an average external diameter of 100-125 nm and internal diameter is 25-40 nm. However, when grown in nickel-chrome cathode, the nanotubes have better quality and smaller walls. No additional treatments are necessary.