Diffusion-controlled H2 sensors composed of Pd-coated highly porous WO3 nanocluster films

• DOI: 10.1016/j.snb.2013.09.116
• Publication Date: 2013-10-12T07:01:34Z
• Authors: Meng Zhao; J.X. Huang; C.W. Ong
• Keywords: Tungsten trioxide; Resistive touchscreen; Surface diffusion

Abstract The resistive H 2 sensing properties of palladium-coated highly porous tungsten oxide nanocluster films (Pd/WO 3 ), with the WO 3 layers having different thicknesses (11.2–153 nm) and electrodes at different positions, were investigated at 80 °C. The results were interpreted by using a model involving various mechanisms including surface catalytic dissociation of the H 2 and O 2 molecules, spillover and diffusion of the split species on the surface and inside the WO 3 layer respectively, and the interaction between the species. The validity of the model was further examined by investigating the influences of the WO 3 thickness and the electrode position on the H 2 sensing properties. The results of data analysis confirm the important role of the diffusion of the split species in the WO 3 layer. The optimum sensor is characterized by having an ultrathin WO 3 nanocluster film with a thickness ≈11 nm, which exhibits a strong sensor response; short response time and recovery time, and stable resistant output during the hydrogenation process.