Electroless plated SnO2–Pd–Au composite thin film for room temperature H2 detection

Extremely thin SnO2 nanosheets with high surface area were fabricated through a one-pot hydrothermal method. In this work, gas sensing property of the SnO2 nanosheets was studied. SnO2–Pd–Au mixed thin films were prepared by electroless deposition of Pd, Au, and nanostructured SnO2 onto the surface of a high resistance alumina substrate. The whole fabrication process was carried out at room temperature without any thermal treatment required. The films deposited on the alumina substrate were characterized by SEM and EDS. The co-deposited Au improved the electric conductance of the sensing film. A relatively large amount of Pd (Pd/Sn ratio around 1:1) was obtained for the film instead of the usually low doping value of Pd (∼0.1% level) for SnO2 hydrogen sensor. It has been found that the SnO2–Pd–Au composite film sensor has fast response in the range of 134–1469 ppm toward hydrogen gas at room temperature. The sensor also shows good stability and repeatability. Effects of annealing condition of the sensing film on H2 gas sensing performance was investigated as well. A possible machnism for SnO2–Pd room temperature hydrogen sensing is proposed.

► Extremely thin SnO2 nanosheets with high surface area were fabricated.
► SnO2–Pd mixed thin films were prepared by electroless deposition with Au.
► The thin film shows fast response toward hydrogen in a wide concentration range.
► The sensing material is particularly suitable for room temperature detection for H2.
► Both SnO2 and Pd play important roles in the sensing mechanism.