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Highly efficient electronic sensitization of non-oxidized graphene flakes on controlled pore-loaded WO3 nanofibers for selective detection of H2S molecules.

Choi SJ, Choi C, Kim SJ, Cho HJ, Hakim M, Jeon S, Kim ID - Sci Rep (2015)

Bottom Line: A tentacle-like structure with randomly distributed pores on the surface of electrospun WO3 NFs were achieved, which exhibited improved surface area as well as porosity.In contrast, porous WO3 NFs with maximized pore diameter showed a high response (Rair/Rgas = 2.8 at 5 ppm) towards large and heavy acetone molecules.Further enhanced sensing performance (Rair/Rgas = 65.6 at 5 ppm H2S) was achieved by functionalizing porous WO3 NFs with 0.1 wt% non-oxidized graphene (NOGR) flakes by forming a Schottky barrier (ΔΦ = 0.11) at the junction between the WO3 NFs (Φ = 4.56 eV) and NOGR flakes (Φ = 4.67 eV), which showed high potential for the diagnosis of halitosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.

ABSTRACT
Tailoring of semiconducting metal oxide nanostructures, which possess controlled pore size and concentration, is of great value to accurately detect various volatile organic compounds in exhaled breath, which act as potential biomarkers for many health conditions. In this work, we have developed a very simple and robust route for controlling both the size and distribution of spherical pores in electrospun WO3 nanofibers (NFs) via a sacrificial templating route using polystyrene colloids with different diameters (200 nm and 500 nm). A tentacle-like structure with randomly distributed pores on the surface of electrospun WO3 NFs were achieved, which exhibited improved surface area as well as porosity. Porous WO3 NFs with enhanced surface area exhibited high gas response (Rair/Rgas = 43.1 at 5 ppm) towards small and light H2S molecules. In contrast, porous WO3 NFs with maximized pore diameter showed a high response (Rair/Rgas = 2.8 at 5 ppm) towards large and heavy acetone molecules. Further enhanced sensing performance (Rair/Rgas = 65.6 at 5 ppm H2S) was achieved by functionalizing porous WO3 NFs with 0.1 wt% non-oxidized graphene (NOGR) flakes by forming a Schottky barrier (ΔΦ = 0.11) at the junction between the WO3 NFs (Φ = 4.56 eV) and NOGR flakes (Φ = 4.67 eV), which showed high potential for the diagnosis of halitosis.

No MeSH data available.


Related in: MedlinePlus

Schematic illustration of synthetic process for the porous WO3 NFs: (a) Electrospinning of the spherical PS-colloid-decorated W precursor/PVP composite NFs, (b) detailed description of the spherical PS-colloid-decorated W precursor/PVP composite NFs, (c) pore size and pore distribution controlled WO3 NFs obtained after high-temperature calcination, (d) sensitizing effect of non-oxidized graphene flake functionalized porous WO3 NFs.
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f1: Schematic illustration of synthetic process for the porous WO3 NFs: (a) Electrospinning of the spherical PS-colloid-decorated W precursor/PVP composite NFs, (b) detailed description of the spherical PS-colloid-decorated W precursor/PVP composite NFs, (c) pore size and pore distribution controlled WO3 NFs obtained after high-temperature calcination, (d) sensitizing effect of non-oxidized graphene flake functionalized porous WO3 NFs.

Mentions: A schematic illustration for obtaining porous WO3 NFs using spherical PS colloids and the composite of NOGR-loaded porous WO3 NFs is shown in Figure 1. The nonwoven WO3 NFs can be obtained by a conventional single nozzle electrospinning of the W precursor (ammonium metatungstate hydrate)/PVP composite solution followed by high-temperature calcination. During the preparation of the electrospinning solution, insoluble PS colloids were added and dispersed homogeneously within composite electrospinning solution. After the electrospinning, the spherical PS colloids were decorated on the surface as well as embedded in the W precursor/PVP composite NFs (Figures 1a and b). The spherical PS colloids and the PVP were eliminated, and W precursor was oxidized to form WO3 NFs during the high-temperature calcination process. A distinctive morphological uniqueness indicated that the spherical pores on the surface as well as inside of the WO3 NFs were generated as a result of the decomposition of the spherical PS colloids (Figure 1c). It is advantageous that the pore size and the distribution can be controlled in WO3 NFs by using different sizes of PS colloids in the electrospinning solution, which will provide better gas-sensing performance by increasing surface area and, thus, facilitating the gas penetration path through the pores. In addition, the sensitization effect of NOGR flakes can further enhance the sensing characteristics when the porous WO3 NFs are functionalized with NOGR flakes (Figure 1d).


Highly efficient electronic sensitization of non-oxidized graphene flakes on controlled pore-loaded WO3 nanofibers for selective detection of H2S molecules.

Choi SJ, Choi C, Kim SJ, Cho HJ, Hakim M, Jeon S, Kim ID - Sci Rep (2015)

Schematic illustration of synthetic process for the porous WO3 NFs: (a) Electrospinning of the spherical PS-colloid-decorated W precursor/PVP composite NFs, (b) detailed description of the spherical PS-colloid-decorated W precursor/PVP composite NFs, (c) pore size and pore distribution controlled WO3 NFs obtained after high-temperature calcination, (d) sensitizing effect of non-oxidized graphene flake functionalized porous WO3 NFs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308697&req=5

f1: Schematic illustration of synthetic process for the porous WO3 NFs: (a) Electrospinning of the spherical PS-colloid-decorated W precursor/PVP composite NFs, (b) detailed description of the spherical PS-colloid-decorated W precursor/PVP composite NFs, (c) pore size and pore distribution controlled WO3 NFs obtained after high-temperature calcination, (d) sensitizing effect of non-oxidized graphene flake functionalized porous WO3 NFs.
Mentions: A schematic illustration for obtaining porous WO3 NFs using spherical PS colloids and the composite of NOGR-loaded porous WO3 NFs is shown in Figure 1. The nonwoven WO3 NFs can be obtained by a conventional single nozzle electrospinning of the W precursor (ammonium metatungstate hydrate)/PVP composite solution followed by high-temperature calcination. During the preparation of the electrospinning solution, insoluble PS colloids were added and dispersed homogeneously within composite electrospinning solution. After the electrospinning, the spherical PS colloids were decorated on the surface as well as embedded in the W precursor/PVP composite NFs (Figures 1a and b). The spherical PS colloids and the PVP were eliminated, and W precursor was oxidized to form WO3 NFs during the high-temperature calcination process. A distinctive morphological uniqueness indicated that the spherical pores on the surface as well as inside of the WO3 NFs were generated as a result of the decomposition of the spherical PS colloids (Figure 1c). It is advantageous that the pore size and the distribution can be controlled in WO3 NFs by using different sizes of PS colloids in the electrospinning solution, which will provide better gas-sensing performance by increasing surface area and, thus, facilitating the gas penetration path through the pores. In addition, the sensitization effect of NOGR flakes can further enhance the sensing characteristics when the porous WO3 NFs are functionalized with NOGR flakes (Figure 1d).

Bottom Line: A tentacle-like structure with randomly distributed pores on the surface of electrospun WO3 NFs were achieved, which exhibited improved surface area as well as porosity.In contrast, porous WO3 NFs with maximized pore diameter showed a high response (Rair/Rgas = 2.8 at 5 ppm) towards large and heavy acetone molecules.Further enhanced sensing performance (Rair/Rgas = 65.6 at 5 ppm H2S) was achieved by functionalizing porous WO3 NFs with 0.1 wt% non-oxidized graphene (NOGR) flakes by forming a Schottky barrier (ΔΦ = 0.11) at the junction between the WO3 NFs (Φ = 4.56 eV) and NOGR flakes (Φ = 4.67 eV), which showed high potential for the diagnosis of halitosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.

ABSTRACT
Tailoring of semiconducting metal oxide nanostructures, which possess controlled pore size and concentration, is of great value to accurately detect various volatile organic compounds in exhaled breath, which act as potential biomarkers for many health conditions. In this work, we have developed a very simple and robust route for controlling both the size and distribution of spherical pores in electrospun WO3 nanofibers (NFs) via a sacrificial templating route using polystyrene colloids with different diameters (200 nm and 500 nm). A tentacle-like structure with randomly distributed pores on the surface of electrospun WO3 NFs were achieved, which exhibited improved surface area as well as porosity. Porous WO3 NFs with enhanced surface area exhibited high gas response (Rair/Rgas = 43.1 at 5 ppm) towards small and light H2S molecules. In contrast, porous WO3 NFs with maximized pore diameter showed a high response (Rair/Rgas = 2.8 at 5 ppm) towards large and heavy acetone molecules. Further enhanced sensing performance (Rair/Rgas = 65.6 at 5 ppm H2S) was achieved by functionalizing porous WO3 NFs with 0.1 wt% non-oxidized graphene (NOGR) flakes by forming a Schottky barrier (ΔΦ = 0.11) at the junction between the WO3 NFs (Φ = 4.56 eV) and NOGR flakes (Φ = 4.67 eV), which showed high potential for the diagnosis of halitosis.

No MeSH data available.


Related in: MedlinePlus