Gas-Sensitive Behavior Based on Charge Transfer Processes of a Novel Polyoxometalate (POM)/TiO<sub>2</sub>/SiO<sub>2</sub> Composite Film

The POM/TiO2/SiO2 Supermolecule composite based on POM films were synthesized via an easy liquid phase deposition method (LPD) at low processing temperature for the first time and employed for studying the charge transfer processes between the film and ambient atmospheres. Here the POM is the Keggin type lacunary FeW11O399- (FeW11) polyanion. Gaseous adsorption properties of the films to noxious gases such as NH3 show that the composite is much better than that of the TiO2/SiO2 films, which may be attributed to the enhancement of the gaseous adsorption ability on the film surface as well as the modified charge transfer process between the adsorbed gases and the films due to the inducing of POM into TiO2/SiO2 matrix. In addition, more importantly, compared with the TiO2/SiO2 films, the POM/TiO2/SiO2 films showed relative faster response and recovery time at optimal working temperature of 440 K, indicating that the films have great potential to be designed as gas sensor used at low temperature.