Application of vanadium oxide nanoparticles in smart surfaces

• Autor(a) principal: Marques, Catarina Costa e
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/58089
• topic: Vanadium oxides; hydrothermal synthesis; microwave irradiation; nanosheets; phase transitions; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

Vanadium oxides (VOx) have been extensively investigated due to their many phases and range of properties, such as eletrochromic, thermochromic and electrochemical. Therefore, this promising materials may be implemented as energy efficiency materials in many sectors like military, industrial, domestic and transport. In the present dissertation VOx phases and nanostructures have been synthesized by hydrothermal synthesis using microwave irradiation as heating source. The synthesis parameters, such as reducing agent, dissolution method and the hydrothermal parameters temperature, reducing agent concentration and ratios were vary and studied to observe their impact in morpholy and the resultant VOx phase. Several pure and combination of VOx phases were achieved, such as VO2 (B), V6O13, V3O7, VO2 (M2) and V2O5. The structural composition and morphology of the as-obtained powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Additionally, to observe a possible transition temperature of the samples a thermogravimetry and differential scanning calorimetry (TG-DSC) analysis were performed. Furthermore, nanosheets were layered in fluorine doped tin oxide (FTO) and Indium tin oxide (ITO) and applied as cathode, with a maximum current of 1.75 mA for ITO and 1.46 mA for FTO.