Nanocomposite of cobalt oxide nanocrystals and single-walled carbon nanotubes for a gas sensor application

A polymer-assisted deposition method was used to prepare nanocomposite structures of cobalt oxide and single-walled carbon nanotubes (SWCNTs) for a gas sensor application. Scanning electron microscopy images show that the deposition morphology of Co3O4 is closely related to the viscosity and metal ion concentration in the precursor solution. X-ray diffraction data combined with Raman spectra show that the composite film has high crystalline quality. The basic sensing behavior was evaluated with NOx gas as an electron-accepting gas and H2 as an electron-donating gas. The composite shows a response of ∼200% upon exposure to 4% H2 at room temperature. This value is higher than that observed in SWCNT thin film and Co3O4 film, as well as in other pure and functionalized CNTs. The enhancement may have originated from the combination of the nature of Co3O4 particles that actively react with gases and the formation of an electrical continuum between Co3O4 and SWCNTs.