Hybrid titania–zincphthalocyanine nanostructured multilayers with novel gas sensing properties

Gas sensors based on hybrid ZnPc–TiO2 nanostructures, produced by molecules and clusters both deposited by supersonic beams, demonstrate enhanced properties in terms of sensitivity, stability and recovery times with respect to pure ZnPc. The hybrid sensors produced by successive deposition of the molecules and the TiO2 clusters show the ability to detect reducing gases, such as methanol, to which the response of metal-phthalocyanines is quite poor. A mechanism based on the formation of chemical bonding, activated by the kinetic energy of the molecules and the strong reactivity of the inorganic clusters, is proposed as being at the basis of electron transfer occurring between the inorganic nanostructure and the molecule. This mechanism would explain the rise of new gas sensing properties of this novel class of nano-hybrid materials.