Material and gas-sensing properties of tungsten oxide nanorod thin-films

Tungsten oxide thin-films were deposited simply by drop-casting a solution containing single-crystalline and monodispersed W18O49 nanorods prepared by a large-scale colloidal synthesis route. They were verified to be highly porous, nonstoichiometric, and monoclinic crystal structure only with little carbon impurities. These material properties heavily reflect relevant nanostructural characteristics of the nanorods acting as a basic building block. It could be comprehended by the observed structure of randomly arranged tungsten oxide agglomerates formed by favorable parallel alignment of individual nanorod units. Tungsten oxide nanorod sensors exhibit sensitive detection capability even at room temperature to various reducing volatile organic compounds (VOCs). This anomalous performance seems to result from unique nanostructural features of the thin-films, allowing a high surface-to-volume ratio and a considerable amount of active sensing sites due to the highly anisotropic, nonstoichiometric structure of W18O49 nanorods.