Synthesis and gas-sensing properties of MnO$_{2-x}$ and MnO$_{2-x}$/CuO-coated multiwalled carbon nanotube nanocomposites

Nanocomposites based on multiwalled carbon nanotubes (MWCNT) with manganese dioxide MnO$_{2-x}$ and copper oxide (CuO) were obtained and investigated. The morphology and elemental composition of MWCNT-layer and nanocomposites MWCNT/MnO$_{2-x}$, MWCNT/MnO$_{2-x}$/CuO were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing response of MWCNT-layer and nanocomposites upon exposure to hydrogen sulfide (H$_2$S) and nitrogen dioxide (NO$_2$) was demonstrated at room temperature. Effect of increasing the conductivity of MWCNT-layer and nanocomposites upon exposure to NO$_2$ indicates these nanomaterials have conductive of $p$-type. Copper oxide in nanocomposite significantly enhances the gas sensing response to H$_2$S.