Multilayer porous Pd-WO3 composite thin films prepared by sol-gel process for hydrogen sensing

Abstract

Based on sol-gel, multilayer porous Pd-WO3 composite thin films have been successfully prepared by utilizing a layer-by-layer deposition strategy. The crystal structure and microstructure were analyzed by various characterization methods. The sensing performance of the prepared films at different hydrogen concentrations and the temperature was studied. Results show that the performance of the hydrogen sensor can be improved greatly by the use of composite structure and soft template (Pluronic F127). The response performance of 1 mol% porous Pd-WO3 composite films was better than that of 2–10 mol% films. The porous Pd-WO3 composite films showed a high sensitivity (~346.5 times better than the sensitivity of pure WO3 films for 1000 ppm H2) and a fast response time (7 s) at the temperature of 250 °C. Porous Pd-WO3 composite films had good selectivity for hydrogen and stable sensing performance. The different response and recovery behavior of samples were contrasted and discussed to explain the effect of the special composite structure and porous structure on hydrogen sensing performance.