Síntesis y caracterización de óxido de grafeno y óxido de grafeno reducido

Abstract

In the present degree work, the synthesis and characterization of graphite oxide (GO) and reduced graphite oxide (rGO) was performed; after comparing different methods that exist to oxidize graphite, it was finally experimented based on the changed Hummers method; starting with potassium permanganate aliquots. Besides, the addition of sodium nitrate to oxidize graphite was omitted. With his modification it was expected to eliminate toxic gases such as nitrogen dioxide and residual contamination from sodium and nitrate ions. For the rGO, some reduction techniques were discarded because their synthesis process was not environmentally friendly, so it was decided to use two reducing agents; ascorbic acid and citric acid. With the characterization of the rGO, it was concluded that, the reduction process with ascorbic acid was more effective since the reduction with citric acid cannot be carried out for long times and that the functional groups it provides cause deeper oxidation on the GO layers. After the synthesis process was completed, each material was characterized by SEM-EDS, FT-IR, Uv-Vis, and Raman spectroscopy. Using SEM, large-leafed, high-purity graphite, a wrinkled graphite oxide with its typical veil shape, and a characteristically reduced graphite oxide were observed, as if the GO had been unfolded. From FT-IR spectroscopy, peaks of GO and rGO were obtained, representing the carboxyl, epoxy and hydroxyl groups, and likewise the loss of some of these after the reduction process. Through Uv-Vis the characteristic peaks of GO and rGO were gotten; at 229 nm and 272 nm, respectively. Finally, with the Raman spectroscopy, it was confirmed that the got material was GO and rGO when corroborating it with scientific literature.