Enhanced hydrogen sensing performance of tungsten activated ZnO nanorod arrays prepared on conductive ITO substrate

We report for the first time, the H2 sensing properties of tungsten activated ZnO (W:ZnO) films prepared on electrically conductive Indium Tin Oxide (ITO) coated glass substrate by spray pyrolysis technique. Microstructure, morphology and optical properties of W:ZnO films prepared with different W dopant concentrations were investigated. All the deposited films show a hexagonal wurtzite crystal structure with preferred orientation along the c-axis perpendicular to the ITO substrate. The optical absorption results revealed increase in band gap and improvement in transmission upto 3% W incorporation in ZnO. The improved crystallinity of the ZnO film revealed from increase in intensity of photo emission, established the possibility of development of a sensor device with W dopant at 3% level. The energy dispersive X-ray elemental analysis of the samples confirmed the incorporation of W ions into ZnO lattice. SEM results show the influence of W catalyst on the uniform and well-aligned growth of ZnO nanorods with unique shape on ITO substrate, which provided higher capture efficiency favorable for Hydrogen (H2) sensing. Gas sensing properties of W:ZnO films were studied at room temperature for different H2 concentrations (from 100 to 400 ppm). It was demonstrated that W doping play an important role in defining the enhancement of sensor response towards H2. Our results show fast response and recovery time for 3% W:ZnO film, suitable for high performance H2 gas detection.