Enhancement of H2S-sensing performances with Fe-doping in CaCu3Ti4O12 thin films prepared by a sol-gel method

In this work, the effects of Fe-doping on structural and gas-sensing properties of CaCu3Ti4O12 (CCTO) thin film prepared by a sol-gel method were systematically studied. Sol-gel-derived CCTO thin films with different Fe-doping concentrations were deposited on alumina substrates by spin-coating and Au/Cr interdigitated electrodes were patterned onto the films by photolithography, sputtering and lift-off processes. Characterizations by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray photoemission spectroscopy and Xray absorption near edge structure confirmed the perovskite CCTO phase with TiO2 and CuO secondary phases and suggested the substitution of Fe3+ ions at Ti4+ sites of CCTO structure. From gas-sensing measurements, Fe dopants greatly enhance H2S response, response time and H2S selectivity against NH3, CO, C2H2, CH4, ethanol and NO2. In particular, 9 wt% (similar to 3 at%) Fe-doped CCTO sensor exhibited the highest response of similar to 126 to 10 ppm H2S, which was more than one order of magnitude higher than that of the undoped CCTO sensor at a low optimum operating temperature of 250 degrees C. The roles of Fe-dopant on gas-sensing mechanisms of CCTO sensor were proposed. (C) 2015 Elsevier B.V. All rights reserved.