Macroporous TiO2 thin film gas sensors obtained using colloidal templates

Chemical and physical synthesis routes were combined to prepare macroporous TiO2 thin films by RF sputtering onto poly methyl methacrylate (PMMA) microsphere templated substrates. The organic template was removed by thermal decomposition at 450 °C leaving a thin layer of TiO2 anatase hollow hemispheres with diameter commensurate with that of the original PMMA microspheres (800 nm). This unique morphology increased active surface area while reducing the deleterious interfacial effects between film and substrate leading to substantially enhanced NO2 sensitivity.