p-/n-Type Switching in the Ag/BTO/TiO2 Nanocomposite as a Gas Sensor toward Ethanol, Liquefied Petroleum Gas, and Ammonia

A novel Ag/BTO/TiO2 nanocomposite was preparedusingchemical reduction and sol-gel techniques followed by sinteringat & SIM;950 & DEG;C to grow rutile TiO2 and remove organicmaterials and hydroxyl groups. The structural, optical, morphological,dielectric, and gas-sensing properties were investigated using X-raydiffraction, Fourier transform infrared spectroscopy, ultraviolet-visiblespectroscopy, scanning electron microscopy, energy dispersive X-rayspectroscopy, and inductance, capacitance, and resistance meter, respectively.The surface plasmon resonance peak of Ag was observed at 428 nm, andthe absorption edge of the Ag/BTO/TiO2 nanocomposite wasobserved at 235 nm, with an energy bandgap of 5.42 eV. The dielectricconstant is lower at 25 & DEG;C and becomes highest at 350 & DEG;Cand low frequency. The percentage response is better toward ammoniathan ethanol and liquefied petroleum gas (LPG) at 25 & DEG;C, whileit is greater, & SIM;87%, for LPG at a higher temperature. The p-/n-typeswitching and vice versa were recorded in the whole gas-sensing measurement.During response-recovery time, the device performed as n typefor ethanol and ammonia and p type for LPG, with a very fast responsetime of & SIM;4 s for all gases. The recovery time for ethanol wasachieved at 20-25 s, while for LPG and ammonia, it was & SIM;60s. Moreover, the negative and positive activation energies also confirmthe switching behavior in the novel Ag/BTO/TiO2 nanocomposite.