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Growth of carbon nanowalls at atmospheric pressure for one-step gas sensor fabrication.

Yu K, Bo Z, Lu G, Mao S, Cui S, Zhu Y, Chen X, Ruoff RS, Chen J - Nanoscale Res Lett (2011)

Bottom Line: However, Raman and X-ray photoelectron spectroscopies confirmed that most of the oxygen groups could be removed by thermal annealing.A gas-sensing device based on such CNWs was fabricated on metal electrodes through direct growth.The sensor responded to relatively low concentrations of NO2 (g) and NH3 (g), thus suggesting high-quality CNWs that are useful for room temperature gas sensors.PACS: Graphene (81.05.ue), Chemical vapor deposition (81.15.Gh), Gas sensors (07.07.Df), Atmospheric pressure (92.60.hv).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA. jhchen@uwm.edu.

ABSTRACT
Carbon nanowalls (CNWs), two-dimensional "graphitic" platelets that are typically oriented vertically on a substrate, can exhibit similar properties as graphene. Growth of CNWs reported to date was exclusively carried out at a low pressure. Here, we report on the synthesis of CNWs at atmosphere pressure using "direct current plasma-enhanced chemical vapor deposition" by taking advantage of the high electric field generated in a pin-plate dc glow discharge. CNWs were grown on silicon, stainless steel, and copper substrates without deliberate introduction of catalysts. The as-grown CNW material was mainly mono- and few-layer graphene having patches of O-containing functional groups. However, Raman and X-ray photoelectron spectroscopies confirmed that most of the oxygen groups could be removed by thermal annealing. A gas-sensing device based on such CNWs was fabricated on metal electrodes through direct growth. The sensor responded to relatively low concentrations of NO2 (g) and NH3 (g), thus suggesting high-quality CNWs that are useful for room temperature gas sensors.PACS: Graphene (81.05.ue), Chemical vapor deposition (81.15.Gh), Gas sensors (07.07.Df), Atmospheric pressure (92.60.hv).

No MeSH data available.


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Gas sensing performance of as-produced CNWs. (a) SEM image of CNWs bridging two neighboring Au fingers of an interdigitated electrode. Gases are detected by measuring the change in the device current while applying a constant dc bias to the device. (b) Room-temperature sensing response for NO2 and NH3.
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Figure 5: Gas sensing performance of as-produced CNWs. (a) SEM image of CNWs bridging two neighboring Au fingers of an interdigitated electrode. Gases are detected by measuring the change in the device current while applying a constant dc bias to the device. (b) Room-temperature sensing response for NO2 and NH3.

Mentions: To demonstrate the gas sensing performance of the as-grown CNWs, CNWs were grown on interdigitated Au electrodes. The interdigitated electrodes with finger width and inter-finger spacing both of 1 μm were fabricated by an e-beam lithography process and used as the sensor substrates [54]. The growth duration was 5 min as it was found that this exposure would yield a CNW film with CNWs connecting with the two neighbouring electrodes (Figure 5a). The sensor operated at room temperature and was periodically exposed to clean dry air flow of 2 lpm for 10 min to record a base value of the sensor conductance, NO2 (100 ppm) or NH3 (1%) diluted in air of 2 lpm for 15 min to register a sensing signal, and then a lab air flow of 2 lpm again for 25 min to recover the device. A constant dc bias (= 0.1 V) was applied across the two gold terminals.


Growth of carbon nanowalls at atmospheric pressure for one-step gas sensor fabrication.

Yu K, Bo Z, Lu G, Mao S, Cui S, Zhu Y, Chen X, Ruoff RS, Chen J - Nanoscale Res Lett (2011)

Gas sensing performance of as-produced CNWs. (a) SEM image of CNWs bridging two neighboring Au fingers of an interdigitated electrode. Gases are detected by measuring the change in the device current while applying a constant dc bias to the device. (b) Room-temperature sensing response for NO2 and NH3.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211258&req=5

Figure 5: Gas sensing performance of as-produced CNWs. (a) SEM image of CNWs bridging two neighboring Au fingers of an interdigitated electrode. Gases are detected by measuring the change in the device current while applying a constant dc bias to the device. (b) Room-temperature sensing response for NO2 and NH3.
Mentions: To demonstrate the gas sensing performance of the as-grown CNWs, CNWs were grown on interdigitated Au electrodes. The interdigitated electrodes with finger width and inter-finger spacing both of 1 μm were fabricated by an e-beam lithography process and used as the sensor substrates [54]. The growth duration was 5 min as it was found that this exposure would yield a CNW film with CNWs connecting with the two neighbouring electrodes (Figure 5a). The sensor operated at room temperature and was periodically exposed to clean dry air flow of 2 lpm for 10 min to record a base value of the sensor conductance, NO2 (100 ppm) or NH3 (1%) diluted in air of 2 lpm for 15 min to register a sensing signal, and then a lab air flow of 2 lpm again for 25 min to recover the device. A constant dc bias (= 0.1 V) was applied across the two gold terminals.

Bottom Line: However, Raman and X-ray photoelectron spectroscopies confirmed that most of the oxygen groups could be removed by thermal annealing.A gas-sensing device based on such CNWs was fabricated on metal electrodes through direct growth.The sensor responded to relatively low concentrations of NO2 (g) and NH3 (g), thus suggesting high-quality CNWs that are useful for room temperature gas sensors.PACS: Graphene (81.05.ue), Chemical vapor deposition (81.15.Gh), Gas sensors (07.07.Df), Atmospheric pressure (92.60.hv).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA. jhchen@uwm.edu.

ABSTRACT
Carbon nanowalls (CNWs), two-dimensional "graphitic" platelets that are typically oriented vertically on a substrate, can exhibit similar properties as graphene. Growth of CNWs reported to date was exclusively carried out at a low pressure. Here, we report on the synthesis of CNWs at atmosphere pressure using "direct current plasma-enhanced chemical vapor deposition" by taking advantage of the high electric field generated in a pin-plate dc glow discharge. CNWs were grown on silicon, stainless steel, and copper substrates without deliberate introduction of catalysts. The as-grown CNW material was mainly mono- and few-layer graphene having patches of O-containing functional groups. However, Raman and X-ray photoelectron spectroscopies confirmed that most of the oxygen groups could be removed by thermal annealing. A gas-sensing device based on such CNWs was fabricated on metal electrodes through direct growth. The sensor responded to relatively low concentrations of NO2 (g) and NH3 (g), thus suggesting high-quality CNWs that are useful for room temperature gas sensors.PACS: Graphene (81.05.ue), Chemical vapor deposition (81.15.Gh), Gas sensors (07.07.Df), Atmospheric pressure (92.60.hv).

No MeSH data available.


Related in: MedlinePlus