Designing hierarchical 1-D metal oxides nanostructures by hydrothermal reaction
A basic goal of making nanomaterials has been to develop nanostructures with high specific surface areas that exhibit the potential to direct the path for electron transport. Very recently, a new class of low dimensional nanomaterials - the 1-D nanostructure - has emerged to be a promising building block that can fulfil these unique characteristics. While there have been a number of reports on the preparation of 1-D nanomaterials, the ability to assemble 1-D nanomaterials into highly-ordered structures remains a challenge.
The aim of this project is to solve this limitation by building a fundamental understanding into the growth mechanisms of anisotropic nanostructures.
Major achievements and highlights
Preliminary results showed that titanium dioxide nanorods with different shapes including well-aligned ‘needle-like’ and ‘Manhattan-tower-like’ morphologies can be successfully prepared by heating TiCl3 at 160°C. Fine tuning of the aspect ratio can be achieved by controlling the aging time and pH of the solution.
Tungsten trioxide nanorods with irregular orientations can be obtained by heating Na2WO4 with SO42- at 180°C. With the addition of oxalic acid, the nanorods assembled into highly ordered microspheres, forming an urchin-like morphology. Similar to the titanium dioxide system, the aspect ratio of the tungsten oxide nanorods is found to be affected by the pH condition.
Future plans and directions
The success of synthesising 1-D nanomaterials is expected to create new opportunities for the fabrication of nanodevices with enhanced functionalities. Subsequent to the success in the synthesis of 1-D nanomaterials, investigation into aligning the growth of nanorods on the conductive supports will be conducted and the photon-to-chemical conversion property will be tested.
