Nanofiber technology expert of The Department of Mechanical Engineering has successfully developed a platform technology whereby semiconductor nanofibers which are not very charge conductive are made highly conductive by inserting carbon materials, such as carbon nanotubes (CNT) and graphene.
Developed by Prof. Wallace Leung, Chair Professor of Innovative Products & Technologies of The Department of Mechanical Engineering, the invention of “Highly Conductive Nano-structures incorporated in Semiconductor” has been recently issued a patent by the United States Patent Office.
With the highly conductive nanofibers, electrons, positive and negative ions can travel along these one-dimensional highways at high speed without getting loss at the boundary of the semiconductor nanofibers, for which recombination of electrons with electrolytes/holes can take place reducing efficiency of the device. There are other attractive properties, such as electron storage, with the carbon nanostructure insert in the nanofibers.
The invention provides a composite with one-dimensional semiconductor nanofibers with highly conductive nanostructures and methods of making these novel composites. For use in Dye Sensitized Solar Cells (DSSC), the composite is able to provide fast charge (electrons and ions) transport, and reduce the rate of electron-hole recombination, ultimately increasing the power conversion efficiency of the DSSC beyond 10% (Yang and Leung, Advanced Materials, 25, 1792 1795, 2013). For use in photocatalysis of pollutant gas such as nitric oxide or VOC, the composite can provide fast electrons transport, storage of electrons and large surface area for adsorption and reaction sites of active molecular species taking part in photocatalytic oxidation, providing superior performance as compared to nanofibers without the conductive materials. For use in biological and chemical sensors, the composite can enhance the sensitivity of the surface for biological and chemical sensing purposes. For use in lithium-ion battery, the composite can lower the impedance and increase the charge storage capacity of the battery. There are still a lot of possible applications that can be explored with this breakthrough technology, according to the Prof. Leung.
*Figure (Right). SEM and TEM images: a) SEM image of TiO2 nanorods incorporating MWCNTs; b) and c) are TEM images, respectively, of MWCNTs and TiO2 nanorods incorporating MWCNTs. d) HRTEM image of TiO2 nanorods that incorporate MWCNTs.