Structural and gas sensing properties of nanocrystalline TiO2:WO3-based hydrogen sensors

Nanocrystalline TiO2:WO3-based hydrogen sensors have been developed by using a sol-precipitation method. Structural and gas-sensing characteristics were performed by using XRD and resistivity measurements. XRD of TiO2 calcined at 600 degrees C for 6 h showed good crystalline quality having a 54 nm grain size. Although these elements were rather slow in response rate, this could be improved significantly by loading the elements further with a noble metal. The operating temperature of the sensors was optimized under different operating conditions. A TiO2:15 wt.% WO3 sensor doped with 0.5 wt.% Pt showed the maximum response to H-2 with a good selectivity at an operating temperature of 200 degrees C. The response time of the TiO2: 15 wt.%WO3 sensor decreased from about 20 min to 1 min with the Pt-loading. The effect of platinum was seen not only in decreasing the response rate but also in increasing considerably the response to H-2. The electronic interaction between the additive and the oxide semiconductor is proposed to account for the sensitization effects. (c) 2005 Elsevier B.V. All rights reserved.