By Pegah M. Hosseinpour, Northeastern University, Nanomagnetism Group
The Big Picture: Ordered TiO2 Nanotubes as Energy Materials
Ordered arrays of electrochemically-fabricated TiO2 nanotubes, pictured on the right, (versus those synthesized hydrothermally with a random spaghetti shape) are promising candidates for solar energy harvesting.1 Their wide range of photocatalytic applications includes gas-sensing, purification and water splitting to produce hydrogen fuel.
More in Depth: Intelligent Tailoring of TiO2 Nanotube Arrays
The large band gap of common crystal structures of TiO2 (anatase and rutile) makes them active only within the UV range which results in conversion of only ~4% of the solar spectrum.2 Proper doping of TiO2 nanotubes with magnetic elements such as iron and post-synthesis processing treatments can tailor their morphology, crystal structure, electronic structure (such as band gap), and magnetic properties--parameters which are bound to the functionality of these nanostructures.3 Current research at the Nanomagnetism Group of Northeastern University involves development of a proper method to incorporate iron to the TiO2 nanotubes, characterization of the fabricated Fe-doped nanotubes, and evaluation of their catalytic functionality as a function of synthesis method and iron content.
All images courtesy Pegah Hosseinpour. [Top] Lateral view of TiO2 nanotube array. [Bottom] “Nano Hay Bales” or false-colored scanning electron imaging of iron-titanium oxide nanotubes (Featured at the APS Image Gallery, March Meeting 2012)