Hydrothermal synthesis of highly crystalline nanotubes/nanoplates of pure and silver-doped anatase-titania using acid-catalyst-modified sol–gel precursors

Abstract

Highly crystalline nanotubes/nanoplates of pure and Ag-doped anatase-titania (TiO 2 ) having high aspect-ratio have been synthesized, without the involvement of thermal treatment, via the hydrothermal method using the acetic-acidmodified sol-gel processed nanocrystalline pure and Agdoped anatase-TiO 2 as precursors. The samples have been characterized for analyzing their morphology, structure, specific surface-area, and surface-chemistry using the transmission electron microscope, selected-area electron diffraction (SAED), X-ray diffraction, Brunauer-Emmett-Teller specific surface-area measurement, and Fourier transform infrared techniques. It has been observed that the hydrothermal treatment of acid-catyalyst-modified pure and Agdoped nanocrystalline anatase-TiO 2 precursors and the subsequent washing of hydrothermal products result in the formation of nanotubes/nanoplates of pure and Ag-doped anatase-TiO 2 instead of those of hydrogen titanate which is invariably obtained with the use of unmodified-precursors. It has been proposed that the formation of nanotubes/nanoplates of pure and Ag-doped anatase-TiO 2 via the hydrothermal method without the involvement of thermal treatment, under the given processing conditions, is due to the operation of double ion-exchange mechanism which is in contrast to that of conventional single ion-exchange mechanism responsible for the formation of nanotubes of hydrogen titanate. The operation of as-proposed double ion-exchange mechanism has been strongly supported by the experimentally observed variation in the solution-pH involved during the washing treatment of hydrothermal product.

Self-Regeneration Performance and Characterization of Silver-Containing Activated Carbon Fibers Coated by Titanium Dioxide

“…This result otherwise proves that Ag atoms did not replace Ti 4+ to form lattice defects. It is because Ag atom size (1.26 Å) was larger than Ti atom size (0.67 Å), and it was difficult to fit into the TiO 2 lattice [18].…”

Estudo de nanoestruturas de titanato sintetizadas pelo método hidrotérmico

“…A prata pode ser reduzida pelo tratamento com borohidreto (Ma et al, 2004), por irradiação da suspensão com luz UV (Li et al, 2008;Plodinec et al, 2014;Barrocas et al, 2016), ou por tratamento térmico em ar acima de 400 o C (Toledo-Antonio et al, 2009;Cesano et al, 2010;Camposeco et al, 2015). Outra opção é usar nanocristais de TiO2 modificados com prata como precursores da síntese de TNS (Lai et al, 2008;Rodríguez-Gonzáles et al, 2012;Jose et al, 2015).…”