Developing Ethanol Gas Sensors with Nanomaterials Thin Films, Slides of Materials Processing

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OUTLINE

 MOTIVATION

 EXPERIMENTAL METHOD

 RESULTS & DISCUSSION

 OTHER RESEARCH PROJECTS

 INTRODUCTION TO NANOMATERIALS THIN

FILM RESEARCH GROUP

Increasing atmospheric pollution problems:

- Demand of effective and low cost monitoring and controlling systems for detection and quantification of pollution sources - Accurate quantification

• Ability to analyze multiple gas
• Complicated
• Expensive
• Power consumption
• Time consuming
• In laboratory only

MOTIVATION

Standard air pollution measurement

GCMS

Year (^) Composite materials Gas Results

2006 (Geng et.al)

ZnO/Polypyrrole NOx Good selectivity & repeatibility 2007 (Geng et.al)

SnO 2 /PANi Ethanol Operating temperature (60 ° C) 2008 (Kong et.al)

SnO 2 /Polythiophene NOx High sensitivity at room temperature 2009 (Hj. Jumali et.al)

TiO 2 -PANi Ethanol Good response at room temperature

Previous reports on metal oxide/polymer

as gas sensor

SnO 2 TiO 2 and ZnO solutions were prepared using wet chemical method

5 different wt% of PANi powder were directly added to produce composite solutions

Films were prepared by spin coating technique with spinning rate at ~ 2000 rpm for 30 seconds

Au electrode was deposited using sputtering technique

copper characterizations wire

silver paint

substrate

film

Au electrode

EXPERIMENTAL METHOD

RESULTS & DISCUSSION

TEM analysis

SEM analysis and ethanol sensing test of SnO 2 :PANi

SEM analysis and sensor test of TiO 2 :PANi sensor

SEM analysis and ethanol sensing test of ZnO:PANi

ZnO particles

TiO 2 particles

SnO 2 particles

1 TEM analysis

3 SEM analysis and ethanol sensing test of TiO 2 :PANi

200nm

200nm

200nm

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (t)

a.u (voltage)

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (s)

a.u (voltage)

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (s)

a.u (voltage)

TiO 2 : PANi 1:

TiO 2 : PANi 1:

TiO 2 : PANi 1:

3 SEM analysis and ethanol sensing test of TiO 2 :PANi

200nm

200nm

200nm

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (s)

a.u (voltage)

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (t)

a.u (voltage)

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (s)

a.u (voltage)

TiO 2 : PANi 1:

TiO 2 : PANi 1:

TiO 2 : PANi 1:

4 SEM analysis and ethanol sensing test of ZnO:PANi

200nm

200nm

200nm

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (s)

a.u (voltage)

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (s)

a.u (voltage)

0 180 360 540 720 900 1080 1260 1440 1620 1800 time (s)

a.u (voltage)

3.75wt% of PANi

6.25wt% of PANi

5.00wt% of PANi

2 possible mechanisms:

a) The interaction between ethanol molecules and nitrogen atoms of PANi impedes electrons delocalization and charge transport through the PANi chains b) The sorption of vapour into PANi chains cause the chain to swell and increase the conduction path (may probably breaks the conduction path)

Sensing mechanism

Variation of voltage magnitude is due to adsorption and desorption of ethanol gas molecules

REFERENCES

[1] Geng. L, Zhao. Y, Huang. X, Wang. S, Zhang. S, Huang. W & Wu. S. 2006. The preparation and gas sensitivity study of polypyrrole/zinc oxide. Journal of Synthetic Metals 156: 1078- [2] Bai, H. & Shi, G. 2007. Review gas sensors based on conducting polymers. Journal of Sensors 7: 267- [3] Sharma.B.K, Gupta.A.K, Khare.N, Dhawan.S.K. & Gupta. H.C. 2009. Synthesis and characterization of polyaniline-ZnO composite and its dielectric behavior. Journal of Synthetic Metals 159: 391- [4] Nardis. S, Monti.D, Natable.C.D, Amico.A.D, Siciliano.P, Forleo.A.,Epifani. M, Taurino.A, Rella.R, & Paolesse. R. 2004. Preparation and Characterization of Cobalt Porphyrin modified tin dioxide thin films for sensor application. Journal of Sensors and Actuator B. 103: 339- [5] Hosono. K, Matsubara. I, Murayama. N, Woosuck. S, & Izu.N. 2005. Synthesis of Polypyrrole/MoO 3 hybrid thin films and their volatile organic compound gas sensing properties. Journal of Chemistry Material. 17: 349- [6] Matsubara. I, Hosono. K, Murayama. N, Shin.W, & Izu.N. 2004. Synthesis and gas sensing properties of Polypyrrole/ MoO 3 -Layered Nanohybrids. Bulletin of the Chemical Society of Japan. 77:1231- [7] Yamazoe, N. 2005. Review: Toward innovations of gas sensor technology. Journal of Sensors and Actuators B. 108: 2- [8] Choudhury, A. 2009. Polyaniline/silver nanocomposites:Dielectric properties and ethanol vapour sensitivity. Journal of sensor and Actuators B. 138:318- [9] K. Arshak, K., Moore, E., Cunniffe, C., Nicholson, M., & Arshak. A. 2007. Preparation and characterisation of ZnFe2O4/ZnO polymer nanocomposite sensors for the detection of alcohol vapours. Journal of Superlattices and Microstructures 42:479 – 488

OTHER RESEARCH INTEREST

2) QUANTUM DOT (QDs)

1) PRESSURE SENSOR

- Using free lead materials (NBT)

- Different preparation techniques

• Solid state reaction

• Wet chemistry method

- Synthesis CdSe/ZnS core-shell structure

- For pesticides sensor application

Pressure Sensor Result

0 100 200 300 400 500 600 Times (s)

Volt (V)

29 Psi 44 Psi 58 Psi

29 psi

58 psi

44 psi

CdSe solution synthesized at 350 oC for different growth time

CdSe solution CdSe solution under UV-lamp

2) QUANTUM DOT (QDs)