Influence of noble metal loading and effect of temperature on the hydrogen sensing behavior of the platinum sensitized titania nanotubes

Platinum sensitized titania nanotubes (Pt/TiO2 NTs) is a promising material for hydrogen (H-2) sensing. TiO2 NTs powder was prepared through rapid breakdown anodization (RBA) and was sensitized with Pt NPs by chemical reduction of chloroplatinic acid. The morphological characterization revealed the tubular architecture of TiO2 NTs with length around 6 mu m, diameter of about 20 nm and wall thickness measuring about 3 to 4 nm. The structural analysis confirmed the TiO2 NTs to be in anatase phase and Pt NPs to be in FCC crystal structure. Compositional studies established the effective presence of Pt NPs over TiO2 NTs. The vibrational spectroscopic analysis indicated that in TiO2, Ti4+ state is present with the tetragonal arrangement. The thermal stability investigation revealed that the Pt/TiO2 NTs nanocomposites are stable up to 550 degrees C thereby indicating the materials are suitable to be used in the temperatures under present investigation. The thick film H-2 sensor made using a paste of Pt/TiO2 and the sensor behaviour towards H-2 in argon (H-2/Ar) was studied as a function of Pt loading and temperature. Increase in the Pt loading was found to enhance the sensor response initially but at higher loading the response decreased substantially. Sensitivity to hydrogen was found to increase with temperature with the needed linearity. At higher temperatures, the sensor response of the Pt/TiO2 NTs saturated beyond a certain threshold limit. The sensor behaviour was also observed to be selective only to H-2 gas amid the presence of methane, ammonia and nitrogen oxide gases.