Langmuir-Blodgett based growth of rGO wrapped TiO2 nanostructures and their photocatalytic performance

Abstract

Graphene oxide (GO)-titanium dioxide (TiO2) nanocomposite sheets were transferred on to solid substrates by Langmuir-Blodgett method and subjected to heat treatment under different conditions to obtain reduced GO (rGO) wrapped TiO2 nanostructures. The morphology, microstructure and chemical composition of nanocomposite sheets were investigated by employing AFM, STM, HR-TEM, XPS, Raman and FT-IR measurements, which reveal significant influence of heat treatment conditions on the reduction of GO, crystalline phases of TiO2 and the development of composite nanostructures. Heat treatment at 400 °C for 30 min results in the formation of un-agglomerated and uniformly distributed TiO2 nanoparticles in anatase/rutile phases, encapsulated by a few nanometer wraps of rGO. Photocatalytic studies of the nanocomposite sheets coated with methylene blue (MB) overlayer showed strong dependence of photo-degradation on their morphology. The 2-dimensional nanocomposite sheets containing rGO wrapped TiO2 nanoparticles exhibit the highest reduction in MB concentration (∼52 %), which is attributed to the availability and accessibility of un-agglomerated TiO2 nanoparticles encapsulated in rGO wraps and the presence of TiO2 in anatase-rutile phases. The process adopted for the growth of 2-dimensional nanocomposite sheets containing rGO wrapped TiO2 nanoparticles on solid substrate is potentially useful for the development of solid state device structures.