H2-Sensing Performance of 2D WO3 Nanostructure—Effect of Anodization Parameter

In this work, we investigate the effect of HNO3 anodizing solution concentration ranging from 1.5 to 3 M on H2-sensing performance of 2D WO3 nanostructures prepared by anodizing sputtered tungsten films. The thickness of WO3 nanosheets was found to reduce while the crystallinity degraded with increasing HNO3 concentration. However, the nanosheets anodized in 2 M HNO3 exhibited the highest response of 43.4 to 1 vol % H2, which was one order of magnitude larger than those fabricated with other concentrations at the optimal operating temperature of 350 °C. In addition, the optimal nanostructures displayed good H2 selectivity against NO2, CH4, C2H2 and C2H5OH.