Surface modification of carbon nanofibers by HNO3 treatment

A convenient and one-step surface modification method was developed to introduce different functional groups on the surface of herringbone type carbon nanofibers (CNFs) by treating with nitric acid solution. The modified CNFs were characterized by various techniques such as X-ray diffraction (XRD), nitrogen adsorption–desorption isotherms (BET), thermo gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Fourier transform infrared (FT-IR). The XRD studies revealed intensification of graphitization in CNFs as a function of nitric acid treatment. Similarly, the surface modification of CNFs led to enhance the BET surface area from of 112 to 152 m2/g. The XPS investigations indicated the existence of alcoholic (C–OH) and carbonyl (CO) functional groups on the surface of modified CNFs. Moreover, FT-IR studies confirmed the generation of carboxylate, hydroxyl and alcoholic functional groups on the surface of acid-treated CNFs.