Effect of (100) and (001) Hexagonal WO3 Faceting on Isoprene and Acetone Gas Selectivity

Abstract

The hexagonal WO3 polymorph, h-WO3, has attracted attention due to its interatomic channels, allowing for a greater degree of intercalation compared to other WO3 polymorphs. Our research group has previously demonstrated h-WO3 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 Na2WO4∙2H2O and showed (100) faceting. The second sample was synthesized using WCl6 and showed (001) faceting. The gas sensing response of the nanostructured films deposited using the (100) textured h-WO3 sample 1 had a higher response to acetone at 350 °C. The (001) textured h-WO3 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.

SERS Materials with Small‐Molecule Sensitivity for Biological Diagnosis

“…Esophageal cancer, esophagogastric cancer, gastric cancer, pancreatic cancer Ag NWs modified with ZnO NPs [17] Isoprene Esophagogastric cancer, gastric cancer Hexagonal WO 3 [18] Isopropanol Lung cancer, COVID-19 MIL-100 (Fe) [19]…”

Two-Step Solvothermal Process for Nanoarchitectonics of Metastable Hexagonal WO3 Nanoplates

“…Further, a metastable hexagonal polymorph (h-WO 3 , P6/mmm) that exhibits a large network of open hexagonal channels along the c-axis has been reported . It has been shown that this characteristic of h-WO 3 opens a wide range of applications in electrochemical, as well as in electrochromic appliances [6,7], as gas sensors [7][8][9][10] and in photo-catalysis [11,12].…”

“…In other words, it seems impossible to obtain pure h-WO 3 from hydrothermal synthesis. Solvothermal synthesis using WCl 6 as precursor can obtain h-WO 3 free from alkaline ions [8,30,31]. Choi et al [30] has shown that h-WO 3 can be directly synthesized by solvothermal synthesis with WCl 6 as precursor and a water/ethanol mixture solution as solvent with a water content between 2 vol% and 10 vol%.…”

Improved isoprene detection performance of Si-doped WO3 films deposited by sputtering and post-annealing

“…For a brief overview of the current research status of isoprene sensing SMOs, Table 1 summarises the materials studied and their sensing performances published during recent years (2020-2023). [13][14][15][16][17][18][19][20][21][22][23][24][25] The most investigated SMOs for VOC sensing were transition-metal oxides, including In 2 O 3 , SnO 2 , WO 3 , MoO 3 , TiO 2 , ZnO, and Co 3 O 4 , 26 which were usually doped with a small amount of another element (or elements) for higher sensitivity to a particular gas (i.e., the selectivity for this gas). Several of the above SMOs, i.e., In 2 O 3 , 20 ZnO, 17 WO 3 , 21 and Co 3 O 4 , 25 have been studied for isoprene sensing and a number of elements, including Au, 17,21 Pt, 16 Pd, 20 Ti, 27 and Si, 12 have been tried as dopants.…”

“…For a brief overview of the current research status of isoprene sensing SMOs, Table 1 summarises the materials studied and their sensing performances published during recent years (2020–2023). 13–25…”