Effect of (100) and (001) Hexagonal WO(3) Faceting on Isoprene and Acetone Gas Selectivity

The hexagonal [Formula: see text] polymorph, h- [Formula: see text] , has attracted attention due to its interatomic channels, allowing for a greater degree of intercalation compared to other [Formula: see text] polymorphs. Our research group has previously demonstrated h- [Formula: see text] to be a highly sensitive gas sensing material for a flu biomarker, isoprene. In this work, the gas sensing performance of this polymorph has been further investigated in two distinct configurations of the material produced by different processing routes. The first sample was synthesized using [Formula: see text] and showed (100) faceting. The second sample was synthesized using [Formula: see text] and showed (001) faceting. The gas sensing response of the nanostructured films deposited using the (100) textured h- [Formula: see text] sample 1 had a higher response to acetone at 350 °C. The (001) textured h- [Formula: see text] sample 2 favored isoprene at 350 °C. The selectivity of the latter to isoprene is explained in terms of the dangling bonds present on the (001) facets. The tungsten and oxygen dangling bonds present on the (001) plane favor the adsorption of the isoprene molecule over that of the acetone molecule due to the oxygen containing dipole present in the acetone molecule.