Sanjitarani Santra

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  • Ph.D., Materials Science and Engineering, Arizona State University, continuing
  • MS, Chemistry, Arizona State University, 2007
  • MSc. Engg., Materials Science, Indian Institute of Science, Bangalore, 2004

 

I started my work on TiO2 nanotubes in Dr. Crozier’s research group in 2009.  Due to low cost, high availability, benign chemical properties, and activity in UV range, TiO2 has become popular candidate for photocatalytic studies. We have synthesized nanotubes with controllable parameters supported on Ti foil, as well as free standing tubes with both ends of tubes open. It has been shown that photocatalytic properties can be influenced by the phase and the structure of the oxide. Hence, it is important to investigate the optimization of stable combinations of phase and morphology at various annealing temperature conditions. We have studied the tubes at various temperatures in both ex- and in-situ Transmission Electron Microscopy (TEM). The structural and phase characterization of tubes has been investigated by high resolution imaging, selected area diffraction (SAD), electron energy loss spectroscopy (EELS), and Inverse Fast Fourier Transformation (IFFT) analysis.

To enhance the catalytic activity of TiO2, it is doped, or functionalized, with different metal systems. Since most of the well-aligned arrays of nanotubes are supported by Ti foil, transportation of the dopant metal atoms is limited. In most popular impregnation techniques tubes also suffer damage from post heat treatments. In a separate study, we have successfully inserted highly mono dispersed Pt nanoparticles of ~ 2nm, in tubes. The particles were identified by Energy Dispersive X-ray spectroscopy (EDS) in TEM while determining their spatial and size distribution via Scanning Transmission Electron Microscopy (STEM).

Further projects involving bimetallic synthesis of oxide catalyst are in progress.

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SEM images of two types of synthesized TiO2 nanotubes – Tubes supported on Ti foil (a) top (b) bottom part and free standing tubes (c) top (d) bottom part of it.

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Electron energy-loss spectra showing the O K-edge from different TiO2 phases.

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(a) High resolution TEM image of tube annealed at 280oC with Fourier transform of anatase and amorphous regions . (b) Colorized image of a tube showing the distribution of anatase (red) and amorphous (blue) regions.

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In-situ chemical vapor deposition observation in environmental TEM – images of TiO2 nanotubes (a) before and (b) after the W deposition.

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Images acquired with STEM technique – showing uniform dispersion of fine Pt nano particle inside (a) a nanotubes – (b) top (c) middle (d) bottom part of the tube

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In-situ TEM observation of TiO2 nanotubes evolution during annealing at various temperatures.

PUBLICATIONS

1. Individual and Combined Roles of CTBN and Fly Ash in Epoxy System under Compression: Correlation between Microscopic Features and Mechanical Behavior, Journal of Reinforced Plastics and Composites, 2005, 24, 299-313

2. Impact Studies in Elastomer, Fly Ash, and Hybrid-filled Epoxy Composites: Part I – Room Temperature Curing, Journal of Reinforced Plastics and Composites, 2005, 24, 903-922

3. Impact Studies in Elastomer, Fly Ash, and Hybrid-filled Epoxy Composites: Part II – Comparison of Data and Fracture Features of the Samples Cured via a Single Room Temperature and Multiple High Temperatures, Journal of Reinforced Plastics and Composites, 2005, 24, 1013-1024

4.  Growth mechanism of cadmium sulfide nanocrystals, The Journal of Physical Chemistry Letters, 2010, 1, 304

5. In-Situ Transmission Electron Microscopy Investigation of Phase Transformation TiO2 Nanotubes , manuscript under preparation

6. Dispersing Pt metal nanoparticles in supported and freestanding TiO2 nanotube arrays with a one step photoreduction approach, manuscript under preparation

CONFERENCE PRESENTATIONS AND PROCEEDINGS

1. Determining Structure-Property Relations in Inorganic Photocatalyst for Solar Fuel Applications, Solar Fuel Meeting, 2010

2. Effect of TiO2 Nanotube Structure on Photocatalytic Production of Methane, Microscopy and Microanalysis, 2010

3. Determining Structure-Property Relations in TiO2 Photocatalyst for Solar Fuel Applications, MRS spring, 2011

4.  In-situ environmental TEM study of phase and morphological changes of TiO2 nanotubes under different heat treatments, Microscopy and Microanalysis, 2011

5. Structure-Activity correlation in TiO2 nanotubes for photocatalytic reduction of CO2, North American Catalytic Society, 2011

6. In-Situ Observation of W-Deposition in TiO2 Nanotubes, Microscopy and Microanalysis, 2012

CONTACT

sanjita@asu.edu