A facile fabrication of a uniform and homogeneous CNT–TiO2 composite: a microscopic and scattering investigation

Abstract

We demonstrated a facile and robust two-step method to fabricate a carbon nanotube–titania nano composite using spray hydrolysis and a chemical vapour deposition (CVD) technique with control over the morphology and deposition chemistry of reaction. Hierarchically structured NiO doped TiO₂ submicrospheres have been realized by hydrolysis of titanium alkoxide at the water–oil interface of micrometer sized droplets. Utilizing these TiO₂ microspheres, a composite of TiO₂–CNT has been synthesized through the CVD technique. Mesoscopic structural investigations have been carried out on composites using ultra small-angle neutron scattering, and small-angle X-ray scattering. There exist three distinct length scales in the composite microspheres. Thermal evolution of microstructure was investigated by in situ X-ray diffraction which clearly indicates an amorphous to crystalline transition of TiO₂. It is established that the polymorphic phase transition of TiO₂ nanoparticles is associated with the increase in its size. Microscopic studies showed that the TiO₂ substrate has given a uniform growth surface for CNTs. Furthermore, their growth mechanism has been discussed.