Reduced graphene (rGO) and metal semiconductor oxides (MOS) nanocomposites for application as toxic gas sensors

• Grant number: 19/22076-5
• Support Opportunities: Regular Research Grants
• Duration: June 01, 2020 - May 31, 2023
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Valmor Roberto Mastelaro
• Grantee: Valmor Roberto Mastelaro
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated researchers: Luís Fernando da Silva ; Maria Inês Basso Bernardi ; Waldir Avansi Junior

Abstract

The detection of different types of gases is becoming increasingly important in our society due to the need to identify toxic gases and organic vapors for environmental and human safety, for emission/control in the industrial sector and in medical diagnostics. Efforts by the scientific community working in this area of research are dedicated to the research of new materials capable of detecting gases at room temperature, under standard environmental conditions and which have high selectivity and sensitivity. Promising materials with these characteristics are obtained through the association of semiconductor metal oxides (MOS) and reduced graphene (rGO). The association of graphene with MOS, compared to sensors containing only the MOS base, has shown better gas detection performance in many aspects such as sensitivity, response/recovery times and operating temperature. Although different works on this topic have been recently published, many aspects of research in this area still remain open. In this context, the general objective of the research project is to study the sensing properties in relation to different toxic gases of composite materials formed by reduced graphene (rGO) and semiconductor metal oxides (MOS). Determining what are the best conditions (rGO / MOS ratio and MOS morphology) that lead to better sensor properties and the mechanisms involved in the process will be critical to the success of the project. To achieve these goals, we will obtain reduced graphene (rGO) samples from graphene oxide using a laser radiation source; obtain nanostructured powder samples of the metal-semiconductor oxides ZnO, In2O3-SnO2 (ITO), WO3 and CuO by the polymeric precursor method; to obtain nanostructured samples of MOS with different morphologies using nanocellose as a template and finally, to perform the synthesis of MOS/rGO nanocomposites whose sensing properties will be characterized. As innovative aspects of the project, we can highlight the use of laser radiation in the graphene reduction process and the use of nanocellulose as a template to obtain metal oxides with different morphologies. The obtained samples will be characterized by conventional and advanced techniques. Finally, the sensing properties of preselected samples with an adequate resistance value will be evaluated with different toxic gases (CO, CO2, Acetone, Ethanol, NO and O3). We hope with this project to contribute to the scientific and technological development of this important research area through new strategies of synthesis of nanostructured materials producing sensors that act at room temperature and present a better degree of selectivity.Objetivos O Objetivo geral do projeto de pesquisa é o estudo das propriedades sensoras em relação a diferentes gases tóxicos de materiais compósitos formados por grafeno reduzido (rGO) e óxidos metálicos (MOS). Os objetivos específicos são: i)Obter amostras de grafeno reduzido (rGO) de alta qualidade a partir do óxido de grafeno utilizando uma fonte de radiação laser; ii)Obter amostras nanoestruturadas na forma de pó dos óxidos semicondutores metálicos ZnO, In2O3-SnO2 (ITO), WO3 e CuO através do método dos precursores poliméricos; iii)Obter amostras nanoestruturadas dos MOS com diferentes morfologias utilizando nanocellose como template; iv)Obter materiais nanocompositos formados por rGO/MOS. Verificar qual a melhor razão, tamanho de partícula e morfologia dos MOS que levam a uma melhor propriedade dos sensores de gases; v)Caracterizar as amostras obtidas através das técnicas de Difração de Raios-X, Espectroscopia Raman, Microscopia eletrônica de Varredura e Transmissão e Espectroscopia de Fotoelétrons Excitados por Raios-X (XPS) vi)Caracterizar as propriedades sensoras das amostras pré-selecionadas que apresentem um valor adequado de resistência para os testes com diferentes gases tóxicos (CO, CO2, Acetona, Etanol, NO e O3).Resultados Previstos i) Esperamos através deste projeto obter materiais nanocomposit. (AU)