Estudos teórico-experimentais de óxidos de grafeno funcionalizados com fósforo, nitrogênio e enxofre

• Ano de defesa: 2023
• Autor(a) principal: Costa, Tainara Luiza Guerra
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Doutorado em Química; Centro de Ciências Exatas; UFES; Programa de Pós-Graduação em Química
• Palavras-chave em Português: Óxido de grafeno; Funcionalização; RMN no estado sólido; subject.br-rjbn; Química
• Link de acesso: http://repositorio.ufes.br/handle/10/16987

The synthesis of graphene oxide is already widely discussed and studied in the literature since this nanomaterial exhibits several properties that make them useful for applications in different fields. Among these applications, the functionalization of graphene oxide has attracted great interest in recent years. Within this context, this work aims to study the functionalization of graphene oxide with phosphorus, nitrogen and sulfur, using experimental and computational methods. From the experimental point of view, the synthesis and characterization of functionalized oxides were carried out using different routes. Computational simulations were also performed, with the perspective of analyzing structural and chemical details of these materials from the study of properties such as the chemical shielding of the 13C, 31P and 15N nuclei and their respective chemical shifts in nuclear magnetic resonance spectra, besides the interaction energies. The computational models studied in this work, together with the syntheses and characterizations carried out, allowed the proposition that for phosphorus hybrids the presence of P is mainly due to P-O-C type bonds and adsorbed phosphate groups, evidenced by computational and experimental solid-state 13C and 31P NMR results. For nitrogen and sulfur synthesized hybrids, empirical studies showed the presence of N and S concentrations around 1.7 and 2.7 % (m/m), respectively. Furthermore, especially for nitrogen hybrids, the computational studies indicated the occurrence of adsorption in addition to C-N type bonds, which presented theoretical 15N chemical shifts compatible with those presented in the literature. These studies indicated that the interactions between GO and P/N are energetically viable and provided new information regarding the chemical shifts associated with 31P, 15N, and 13C nuclei in these types of materials. It is believed that the models studied and discussed here can contribute to future investigations involving functionalized graphene oxides, besides helping in the interpretation of 31P, 15N, and 13C NMR spectra obtained for materials with similar chemical structure.