Development of morphological dependent chemically deposited nanocrystalline ZnO films for liquefied petroleum gas (LPG) sensor

Nanocrystalline ZnO films were deposited on a glass substrate by a simple chemical method based on the room temperature alternate dipping of the substrate in an alkaline zinc nitrate solution and double distilled water containing 1% H2O2. The dipping time duration significantly affected the ZnO film surface morphology. The relationship between the surface morphology and the sensing properties to liquid petroleum gas (LPG) of the ZnO films is newly established. The ZnO films exhibited the maximum response of 28% at 673 K upon exposure to 0.4 vol.% LPG. Further, due to the application of a noble metal catalyst (Pd) on the surface of the ZnO film, the maximum response improved to 57% at 548 K with reduced response time.