Síntese e caracterização de pontos quânticos de carbono dopados com nitrogênio

Abstract

Carbon nanomaterials, such as carbon quantum dots and graphene oxide, have received the attention of the scientific community in recent years. Its physical and chemical properties, such as water solubility, low toxicity, photoluminescence, suggest several applications in the technological area, such as the preparation of electronic devices at nanoscale and biosensors. Several methods of synthesis of carbon-based materials have been explored, but some have a high cost. In this work, carbon based nano materials were prepared by simple carbonization of citric acid by heat treatment at 200 °C. Nitrogen doping was done using melamine along with citric acid. The characterization of the samples was performed by spectroscopy (UV-VIS, FT-IR, Emission and Excitation), thermal analysis (Thermogravimetry and Thermodifacial Analysis) and potentiometric titration. The results show that the insertion of nitrogen through doping promoted an increase in the intensity of photoluminescence of the samples. By means of the FT-IR and acid-base titration techniques, the insertion of nitrogen into the carbonaceous structure was evidenced, with the formation of secondary amide groups. The number of acid sites in each sample is difficult to determine via acid-base titration due to the presence of functional groups subject to the hydrolysis reaction; which directly affects the determination of acid groups. Although doping with nitrogen makes it possible to determine the equivalence point with greater accuracy.