Multi-walled Carbon Nanotubes Coated by Atomic Layer Deposition of TiO2

Carbon nanotube (CNTs)-metal oxide semiconductor hybrid na- nostructures have been studied since past few years as they ex- ploit the combined properties of both. Due to their high surface area and excellent electrical, mechanical and thermal proper- ties, CNTs combined with metal oxides give an enhanced quality of nanostructures in terms of their structure and morphology which in turn makes them applicable for dif- ferent applications like photocata- lysis, gas sensors, dye-sensitized solar cells and energy storage. In this study multi-walled carbon na- notubes (MWCNTs) were grown by catalytic chemical vapor depo- sition on Si and Si/SiO 2 substrates using Fe catalyst. They were sub- sequently coated by atomic layer deposition (ALD) of TiO 2 from tetrakis(dimethylamido)titanium. Since, ALD is a self-limiting surfa- ce process it is important to unde- rstand how it proceeds on the inert and nanostructured surface of carbon nanotube forest. The- refore, we tested different plasma modifications of MWCNTs surface (oxygen plasma treatment, car- boxyl or amine plasma enhanced chemical vapor deposition) prior to the ALD and also compared thermal and plasma enhanced ALD of TiO 2 . Pristine and modi- fied MWCNTs were characterized by scanning electron microsco- py (SEM), transmission electron microscopy (TEM), X-ray photo- electron spectroscopy (XPS) and Raman spectroscopy.