A Simple Dip-Coating Method of SnO2-NiO Composite Thin Film on a Ceramic Tube Substrate for Methanol Sensing

In this work, SnO2-NiO composite thin film was successfully grown on a ceramic tube substrate directly by a simple dip-coating method combined with annealing. Characterization analysis demonstrates that uniform SnO2 film consists of a great number of nanospheres and NiO grows on SnO2 as an agglomerated block. In comparison to the pure SnO2 sample, the SnO2-NiO composite thin films gas sensor exhibits superior methanol sensing properties at 225 degrees C. The gas response to 10 ppm methanol reached 15.12 and the response and recovery times were 8 s and 7 s, respectively. The excellent selectivity and recovery rate are explained by the unique properties of the NiO semiconductor and the higher sensor response is attributed to the pivotal heterojunction effect.