143-19-1Relevant articles and documents
Shape Transition of TiO2 Nanocube to Nanospindle Embedded on Reduced Graphene Oxide with Enhanced Photocatalytic Activity
Mukhopadhyay, Soumita,Maiti, Debabrata,Saha, Arindam,Devi, Parukuttyamma Sujatha
, p. 6922 - 6932 (2016)
In this study, we report a facile synthetic route for the transition of anatase TiO2 nanocube to nanospindle with coexposed {001} and {101} facets on a reduced graphene oxide (rGO) platform. Initially, a TiO2 nanocubes/graphene oxide suspension in an ethanol-water solvent mixture was hydrothermally treated at 180 °C for various reaction durations to perform the in situ growth of TiO2 and simultaneous reduction of graphene oxide to rGO. All composites resulted in the formation of anatase TiO2 with a surface heterojunction formed by coexposed {101} and {001} facets embedded on an rGO sheet. Interestingly, it was observed that 4 h of hydrothermal treatment resulted in the formation of a TiO2 nanospindle with enhanced {001} high energy facet % embedded on an rGO sheet. The photocatalytic performance of the products was evaluated for the photodegradation of malachite green under simulated solar irradiation. All TiO2@ rGO composites exerted enhanced activity as compared to the native TiO2 cube owing to enhanced adsorption and fast electron migration by the rGO platform. Furthermore, the TiO2 spindle @rGO exhibited the highest photocatalytic activity with a 6 fold increase in efficiency over the native TiO2 cube. This superior performance of the nanospindle was ascribed to the synergistic effect of enhanced {001} facet percentage in the surface heterojunction and close interfacial contact with the rGO platform.
Rapid Synthesis of Sub-10 nm Hexagonal NaYF4-Based Upconverting Nanoparticles using Therminol 66
Hesse, Julia,Klier, Dennis T.,Sgarzi, Massimo,Nsubuga, Anne,Bauer, Christoph,Grenzer, J?rg,Hübner, René,Wislicenus, Marcus,Joshi, Tanmaya,Kumke, Michael U.,Stephan, Holger
, p. 159 - 168 (2018)
We report a simple one-pot method for the rapid preparation of sub-10 nm pure hexagonal (β-phase) NaYF4-based upconverting nanoparticles (UCNPs). Using Therminol 66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs. The upconversion (UC) luminescence properties of the nanocrystals were tuned by varying the concentrations of the dopants (Nd3+ and Yb3+ sensitizer ions and Er3+ activator ions). The size and phase-purity of the as-synthesized core and core–shell nanocrystals were assessed by using complementary transmission electron microscopy, dynamic light scattering, X-ray diffraction, and small-angle X-ray scattering studies. In-depth photophysical evaluation of the UCNPs was pursued by using steady-state and time-resolved luminescence spectroscopy. An enhancement in the UC intensity was observed if the nanocrystals, doped with optimized concentrations of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This was attributed to the suppression of surface-related luminescence quenching effects.
Fatty acid ionic liquids as environmentally friendly lubricants for low friction and wear
Gusain, Rashi,Khatri, Om P.
, p. 3462 - 3469 (2016/01/20)
Vegetable oils are environmentally-friendly, sustainable and rich source of fatty acids, and have been used as lubricants since ancient times. The carboxylic group of fatty acids interacts with metal surface and forms the tribo-chemical thin film of low shear strength under the boundary lubrication, which reduces the friction and the wear. Herein, four fatty acids having variable chain length and unsaturated sites are selected as anionic precursors to prepare the tetrabutylammonium-fatty acid ionic liquids. The preparation of these ionic liquids is confirmed by FTIR and NMR (1H and 13C) analyses. The chain length and degree of unsaturation in the fatty acid anions control the viscosity, melting temperature, crystallization temperature and latent heat of fatty acid ionic liquids. These ionic liquids as lubricants exhibited significantly lower friction (18-50%) compared to polyol ester lube base oil. Further, the degree of friction reduction is largely influenced by the structure of the constituent fatty acid anion. The oleate anion showed the best tribo-performance among all fatty acid ionic liquids being studied. The elemental mapping of worn surfaces revealed the formation of fatty acid ionic liquids constituted a tribo-chemical thin film. Being halogen-free and abundantly available sources of fatty acid precursors, these ionic liquids promise immense potential for tribological applications, where the friction and environment are of prime importance.