Novel Synthesis and Gas Sensing Performances of CuO-TiO2 Nanocomposites Functionalized with Au Nanoparticles

CuO-TiO2 nanocomposites were synthesized on Al2O3 substrates by a novel chemical vapor deposition (CVD) route, based on the sequential growth of CuO matrices (550 degrees C) and the overdispersion of TiO2 (400 degrees C), both performed under O-2 + H2O atmospheres. The obtained supported materials were subsequently functionalized with gold nanoparticles (NPs) by means of radio frequency (rf) sputtering. The system structure, nano-organization, and chemical composition were characterized by a multitechnique approach, using glancing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). For the first time, both CuO-TiO2 and CuO-TiO2-Au nanosystems were tested as resistive gas sensors for toxic and flammable gases (CH3CH2OH, H-2, and O-3), revealing attractive performances even at moderate working temperatures. Interestingly, the functional response could be appreciably enhanced upon introduction of gold NPs, highlighting the present CuO-TiO2-Au nanosystems as appealing candidates in view of technological applications.