Feasibility of H2 sensors composed of tungsten oxide nanocluster films

The hydrogen (H2) sensing properties, including the sensor response, response time and recovery time, of different sensor architectures based on tungsten oxide (WO3) were investigated to assess the feasibility of using WO3 in producing practical H2 sensors. Each of the different sensor architectures consists of 3 layers. The first layer is a 2.5-nm palladium (Pd) layer, which is always deposited onto a highly porous WO3 nanocluster layer. The third layer is an Au/Ti electrode layer, which may be constructed in the form of interdigitated electrodes or 5 × 5 mm2 pad electrodes, which is located either on the top surface of the Pd layer or at the bottom of the WO3 film. Furthermore, the WO3 layer was also constructed to be either 11.2 nm or 153 nm thick. The sensor design consisting of a 2.5-nm Pd layer on an 11.2-nm WO3 layer with interdigitated electrodes at the bottom of the layer was found to exhibit the best overall H2 sensing properties, with excellent cyclic stability over 600 cycles of operation.