Microsphere templating as means of enhancing the sensitivity of thin film metal-oxide gas sensors

Abstract

Chemical and physical synthesis routes were combined to prepare macroporous thin films of semiconducting metal-oxides such as CaCu3Ti 4O12 and TiO2 by pulsed laser deposition onto poly(methyl methacrylate) (PMMA) and poly(styrene) (PS) microsphere templated substrates. Subsequently, the organic microspheres were removed by thermal decomposition. The remaining inorganic films comprised a monolayer of hollow hemispheres with diameter commensurate with that of the microspheres. This unique morphology increases the surface area and reduces the interface area between film and substrate. Consequently, the surface activity is markedly enhanced while deleterious interfacial effects between film and substrate are significantly reduced. Both effects are highly advantageous for gas sensing applications. Indeed, microsphere templated films showed remarkably enhanced gas sensitivity compared with control films deposited onto untreated substrates.