Morphology and Oxidation State Transitions under Hydrothermal Treatment on Vanadium Oxide (V) Systems

This chapter revisits the review in expanded form of “Hydrothermal Synthesis of Vanadium Oxide Microstructures with Mixed Oxidation States” which summarizes many vanadium oxide micro and nano structures displaying different morphologies and V4+ / V5+ rates, most of the synthetic procedures are related to sol – gel synthesis executed with different V5+ oxide precursors namely V2O5, VO(OCH2CH3)3, NH4VO3 and VOCl3 in presence of different organic molecules, most of them acting as templates under self – assembled processes depending on their distinctive features, like surfactants (amphiphilic molecules), reducing agents and coordination ligands, under certain chemical parameters and conditions such as pH, concentration, stoichiometry, water / solvent rate at specific temperatures, which usually leads to different routes like layered intercalation compounds nanocomposites, semi or complete reduced vanadium oxide systems or coordinated systems directed under different building blocks that are predominant in the environmental chemical system. Once the first stage is completed hydrothermal treatment takes place and many processes occurred under higher temperature, pressure changes and time frame reactions, the resultant products display magnificent 1 – D, 2 – D and 3 – D morphologies, with different oxidations states rates and most of these structures are based in different structural vanadium oxides lattices that are able to withstand each system, like V7O162-, V2O4, V6O11 and V4O92-. This chapter focuses on the chemical stages that take place in previous and subsequent to hydrothermal treatment stages and analyses the possible redox reactions and species that could potentially display a major role in the formation of these intricate structures for the purpose of understanding the characteristic for future applications in many technological fields.