Hybrid multiwalled carbon nanotubes and trioxide tungsten nanoparticles for hydrogen gas sensing

The WO3/multiwalled carbon nanotubes (MWNTs) hybrid films were fabricated by spin-coating on an alumina substrate. The structure, morphology, chemical composition and quality of the as-prepared WO3 nanoparticles, functionalized MWNTs and WO3/MWNTs hybrid films were studied by SEM, TEM, XRD, XPS, DLS and Raman spectroscopy methods. Results show that WO3 nanoparticles were nucleated on oxygenated functionalized MWNTs in hybrid suspension. After coating and annealing the films at 350 degrees C, the hybrid WO3/MWNTs films present rather linear gas sensitivity as a function of hydrogen concentrations at 300 degrees C. Results are discussed based on surface increase as well as development of two types of Schottky potential barrier height, one at the n-WO3/p-MWNTs hetero-junction and the other at WO3 grain boundaries.