H 2 S sensing characteristics of Ni-doped CaCu 3 Ti 4 O 12 films synthesized by a sol-gel method

BOONTUM, ARISARA; WISITSORAAT, ANURAT; PHOKHARATKUL, DITSAYUT; HODAK, SATREERAT K.; HODAK, JOSE H.

SENSORS AND ACTUATORS B-CHEMICAL

ELSEVIER SCIENCE SA

Año: 2018 vol. 260 p. 877 - 887

0925-4005

The problem of detecting the toxic hydrogen sulfide (H2S) gas at part per million levels in air by meansof simple solid state gas sensors is relevant to environmental and gas processing industries. In this work,high-performance H2S gas sensors are developed based on nickel-doped calcium copper titanate (NidopedCCTO)thinfilms synthesized by a sol-gelmethod. Fromgas-sensingmeasurements,the response ofNi-doped CCTO sensing films increased substantially with increasing Ni doping level from 1.5 to 7.3 wt%,revealing a catalytic effect of Ni on the surface reactions with adsorbed H2S molecules. In particular,7.3 wt% Ni-doped CCTO sensors offered a high response of 120 for 10 ppm of H2S at the optimal operatingtemperature of 250 ◦C, an order of magnitude higher than that of undoped one. In addition, the responsetime dropped significantly from ∼80 s to ∼4 s while the recovery time slightly improved as the Ni dopingcontentincreased from 0 to 7.3 wt%. Moreover,the Ni-doped CCTO sensors exhibited good reproducibilityand high H2S selectivity against ethanol, H2, NO2 and NH3. Therefore, the Ni-doped CCTO sensors arehighly promising for sensitive and selective detections of H2S.