Facile and one step synthesis of WO3 nanorods and nanosheets as an efficient photocatalyst and humidity sensing material

In this report, large scale WO3 nanorods (NRs) and nanosheets (NSs) are prepared successfully by a facile one-step microwave irradiation method, using tungstic acid as tungsten source and CTAB & PEG as surfactants. TEM images showed that CTAB assisted microwave produced WO3 nanorods (diameter of 20-50 nm, length of 400-500 nm) and nanosheets (widths of 250-300 nm and thicknesses of about 15 nm) was produced with the presence of PEG assisted WO3 samples respectively. Powder XRD result showed that monoclinic phase of WO3 and the consequent pattern is in good agreement with the JCPDS card No. 83-0951. The photocatalytic activity of the catalyst powders were examined by using methylene blue (MB) and congo-red (CR) dyes under visible light irradiation. The results proved that superior catalytic performance of WO3 nanosheets compared to WO3 nanorods towards dye solutions, this could be due to more active surface for the interaction of dye molecules compared to the rods, which results in a more capable degradation of the dye molecules. Humidity sensor results also showed that WO3 nanosheets were high sensing performance, including sensitivity (98%), fast response (25 s)/recovery time (15 s) and high stability than compared to WO3 nanorods.