Functionalization of single-walled carbon nanotubes with a HNO3/H2SO4 mixture through different treatments: A DFT supported study

Chemical functionalization is carried out on Single-Walled Carbon Nanotubes (SWCNT) to improve its surface interaction when used for final application such as for drug carriers. This research compared the effectiveness of ultrasonic treatment and stirring in the functionalization process. Both methods were conducted at room temperature. The functionalization processes were performed by using two different solvents which are nitric acid and a mixture of sulfuric acid and nitric acid (3:1). The result of Fourier Transform Infrared (FTIR) spectra shows the appearance of carboxyl group at 1730 cm−1 for the sonication with mixed acid. Acid contents were determined by Boehm titration and the results show that acid groups are present. Both analyses indicate that the –COOH group is successfully attached on SWCNT surface. The study on density functional theory (DFT) was used to support the experimental results. DFT results show that the increase in the carboxyl group number improves the stability of SWCNT.