Fabrication of CO<sub>2</sub> Gas Sensors Using Graphene Decorated Au Nanoparticles and Their Characteristics

(1)

pISSN 1225-5475/eISSN 2093-7563

Au ™Î‘⁄° ⁄√» ◊°… ‚› CO

²

^°∫æ≠«

¶¤˙ ◊ Ø∫

ËÛ¯1^• Ë≠Í2^• §ÕÛ1,+

Fabrication of CO

2

Gas Sensors Using Graphene Decorated Au Nanoparticles and Their Characteristics

Sang-Jin Bae¹, Kang-San Kim², and Gwiy-Sang Chung^1,+

Abstract

This paper describes the fabrication and characterization of graphene based carbon dioxide (CO²) gas sensors. Graphene was synthesized by thermal decomposition of SiC. The resistivity CO²gas sensors were fabricated by pure graphene and graphene decorated Au nanoparticles (NPs). The Au NPs with size of 10 nm were decorated on graphene. Au electrode deposited on the graphene showed Ohmic contact and the sensors resistance changed following to various CO²concentrations. Resulting in resistance sensor using pure graphene can detect minimum of 100 ppm CO²concentration at 50ôC, whereas Au/graphene can detect minimum 2 ppm CO² concentration at same at 50ôC. Moreover, Au NPs catalyst improved the sensitivity of the graphene based CO²sensors. The responses of pure graphene and Au/graphene are 0.04% and 0.24%, respectively, at 50ôC with 500 ppm CO²concentration. The optimum working temperature of CO²sensors is at 75ôC.

Keywords : Carbon dioxide, Gas sensors, Graphene, Au nanoparticle

1. ≠ –

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2

)

« Ë‚ÆÃ ı°«Ì ÷Ÿ

.

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« ˆ”˚Œ œÕμª ßÿ ˙≈œÌ Û¬°≠ ø¤Ã °…— æ

≠° ‰œŸ

[1].

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CO

2 °∫æ≠¬ Ò–Í ˚‹± Êƒ

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Ìº¸ÿ˙ Êƒ Ó« ©Ø æ˘° ÷Ÿ

.

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.

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,

ﬂ§“⁄ ◊ À‚“⁄

,

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√∫Ã ™⁄Ÿ

.

^—Ì

,

^›μºƒ

CO

2°∫æ≠¬ Í≠∫

,

^{Ø¯∫ °}

∫° Î— Ù∫ ›¿∫

,

^{¸• ›¿”μ}

,

˙ÒÎ˙ “¸≠ Ó« Â°

ßÆ° ˆ›Óˆ ›”Í≠∞ ›μº« ™Î∏∂∞¶ ÷Œ Àˆ∞˙

Œ ÁÎœÌ ÷ˆ∏

,

Â√£ ÁÎ√ ﬂ˝œ¬ ˙◊Ø≠Œ Œ— »§

∫Ã ™¸ˆÌ ¸‚˚ Ø∫ Ø≠° ﬂ˝œ¬ ‹°Ã ÷Ÿ

[2].

ˆ≠ Ó ‚ ø»° ∫“™Î©Í

(CNT)

^¬

COx

^{« ˙Ûμ}

(ppb

^¸ß

)

¸ßÓˆ Àˆ“ ˆ ÷¬ Ø¡— Àˆ ∞˙Œ £÷«˙Ÿ

. CNT

^‚

› °∫æ≠« Ù∫ μ¬ Ïˆ— ¸‚˚ Ø∫

,

^{¤∫ ©‚}

,

^{Ù∫ •}

È˚ Œ« Ò≤˙

CNT

« ÎÎÆ °∫Ì¯Ã °…œˆ∏

,

^{°∫ À}

‚ ƒ ∏π√£Ã ¿ÆŸ

[3, 4].

^{÷Ÿ ∫“¯⁄«}

2

^˜¯

(2D)

^∏∂Œ

◊°…∫

CNT(1D)

∏Ÿ ∂ØœÌ ı Ïˆ— ¸‚˚

,

^{‚Ë˚ ∫˙ª}

°ˆÌ ÷‚ ßÆ° Ø¡—

CO

²°∫Àˆ ∞˙Œ ÆŒ«˙∏Á ‚ Ë˚ ⁄Æ˝ª ÃÎ— Ì∫…

CO

2°∫æ≠° ∏Ì«˙Ÿ

[5].

^◊°

…∫

2D

ÚÈ∏∂Œ Œÿ Ù∫ •È˚ Œ« Ò≤

,

^≠–

/

^{≠ »§∫}

, N/MEMS

« ›μº ¯§Ã °…œ‚ ßÆ° °∫æ≠° Î‹˜ ˚

’œŸ

.

^«—

,

Ù∫ ¸‚¸μμ Ø∫∏Œ

CNT

^{”∏ ΔœÛ Í≠∞}

™Î∏∂∞¶ ÃÎœ¬ ÊÏ∏Ÿ °∫æ≠ ≈£ ‚ΩÃ ˚‚ ßÆ°

‹œ ¯⁄ «¬ –⁄ ˆÿ« ÛμÓˆ Àˆ° °…œŸ

.

^{◊°… ‚›}

1ÔÍÎ–≥ ¸‚¯–Œ(School of Electrical Engineering, University of Ulsan)93 Daehak-ro, Nam-gu, Ulsan 680-749, Korea

2μ´Ã ´ª ⁄ÆΔ(Tokai Carbon Korea) Anseong, Gyeonggi-do, 456-843, Korea

+Corresponding author : [email protected]

(Received : Jan. 10, 2013, Revised : Feb. 4, 2013, Accepted : Feb. 19, 2013)

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/by- nc/3.0)which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

(2)

°∫æ≠« Àˆ ≈øœÚ∫ œ›˚∏Œ μ Õ ˜¡Õ« ™“ª œ¬ °∫ –⁄° ◊°… •È° Ì

/

ª¯ª Îÿ ◊°…« ¸μ∫

« Ø≠Œ ™∏≠Ÿ

[3].

^÷Ÿ

,

^{◊°… •È°}

Pt, Pd

^Õ

Au

^{Ó« ›}

” À≈¶ ⁄√œ© Àˆ°∫« °∫ ±√∫˙ μ‚Ûª ß— °

∫æ≠° ∞ﬂ˜ ¨∏«Ì ÷Ÿ

.

◊°…° À≈Œ· ⁄√» ›” ™ Î‘⁄¬ •È˚ª ø≤˚∏Œ ı°√∞Ì œ‘ˆ¶ Ø≠√¥∏Œ

· °∫æ≠« μÕ °∫ ±√∫ª ‚Û√≥ ˆ ÷Ÿ

[6, 7].

ª ¨∏°≠¬ •È˚ ı°° ˚• μ« ‚Ûª ßÿ

10 nm Au

™Î‘⁄¶ ◊°… •È° ı¯œ© ¸‚˙◊ƒ

CO

2æ≠¶ ¶

¤œ© Ø∫ª Ò≥ –Æœ¥Ÿ

.

2. ¨∏Ê˝

ª ¨∏°≠¬ Û–≠–‚Ûı¯˝

(APCVD)

^{ª Îÿ Ò§˙}

3C-SiC

¶ Ãæ·§∫Âﬂ∏Á ∫¤Õμ˙ ﬁ” ≠≥Æ¯§∏Œ

¸∫» ◊°…ª

SiO

2‚«∏Œ ¸Áœ© ∫¤Õμª Îÿ

Au

^¸

ÿª ı¯œ¥Ÿ

[8].

^{μ ‚Ûª ßÿ}

Au colloid (10 nm, 752584 Aldrich)

¶ ◊°… •È° μ˜ﬂ∏Á

,

^©‚≠

PLL (Poly-L- Lysine solution, P6282 Sigma)

^{∫ ◊°…˙}

Au

^{« ¢’È∏Œ·}

ÁÎœ¥Ÿ

.

^{◊°… •È˙}

Au

‘⁄« ¢¯¬ª ‚Û√∞‚ ßÿ

400

^o

C

^°≠

30

–£ ﬁ”≠≥Æ¶ «√ﬂŸ

. Au/

^◊°…˙

Au

^{° ⁄}

√«ˆ ∫ ◊°…ª ÃÎœ© ¸‚˙◊ƒ

CO

2æ≠¶ ¶¤œ¥

Ì

, Keithely probe station (4200 scs)

^∏Œ

CO

2°∫ æ≠« Ø∫

ª ¯§œ¥Ÿ

.

3. ·˙ ◊ Ì˚

Fig. 1

^{∫ ◊°… •È°}

Au

™Î‘⁄« ı¯ ¸ƒ° Î— ¸‚˙

◊ƒ

CO

2°∫æ≠«

I-V

Ó±∏Œ ¯ˆ ◊°…˙

Au/

^◊°…∫

±¸˚Œ »Õ¢’ Ø∫ª ™∏¬Ÿ

.

^{‚ ˙◊∫ ¢¢}

165

^Õ

144

Ÿ∏Œ ◊°…° ⁄√»

Au

^{™Î‘⁄¬}

2

˜ §ŒÃ ¸∫«Ó ¸⁄

« Ãøª ‚Û√— ˙◊Ã “«¬ Õ∏Œ Á·»Ÿ

.

«—

, Au

° ⁄√» ◊°…∫ •È« ⁄Ø¸⁄¶ Æ°Œœ© ◊

°… •È°

O

2«¬ ¿μ« Ì¯ª Êˆœ¬ ∏£∑ ™“ª œ‚

ßÆ° ºŒ« ¸μ∫Ã ı°» Õ∏Œ Á·»Ÿ

[9].

Fig. 2(a)

^¬

SiO

2 ‚«∏Œ ¸Á» ◊°…« Û∏ ∫ÂÆ≥ª ™

∏Ω Õ∏Œ ◊°…« ·‘ª ™∏ª¬

D

ÍÂÕ Ø∫ª ™∏ª¬

G

ÍÂ ◊ÆÌ ˛ˆÕ ¸√»

2D

ÍÂ« «©Œ ∏∫«Á

1350 cm

^-1

, 1584 cm

^-1^◊ÆÌ

2700 cm

^-1^{°≠ ¢¢ ¸∫»Ÿ}

[10].

^{ª ¨}

∏°≠ ÁÎ» ◊°…∫

D

ÍÂ ©‚° ÛÎ˚∏Œ ¤Δ ·‘Ã ˚ Ì

,

◊°…« ·§∫ «©Œ

G

ÍÂ° ©‘ ™∏μŸ

. I

G

/I

D« ™∫

‡

2.25

^¥∏Á

,

^{‚∏° ∏Ì»}

raphene oxide (GO)

^Õ

Reduced Graphene Oxide (RGO)

° Òÿ Ù∫ ˆ°¶ ∏¥Ÿ

[11].

◊°… •È°

Au

^{° ⁄√» ÊÏ}

, G

^{ÍÂ¶ ‚ÿ∏Œ}

D

^{ÍÂ Ò}

≤∫ ı°œÌ

, G

^{ÍÂ° Òÿ}

2D

ÍÂ« Ò≤∫ “œ¥Ÿ

. D

^Í

Â« Ò≤Ã ÙΔ¯ ÃØ¬ ´ª∏∂°≠ Û⁄Æ° ﬂ˝«Ì

, Au

™Î‘⁄° ı¯«¬ ø» ◊°…« ∞¢ ∏∂° ‹Œ« ∫ÆπŒ (a)

(b)

Fig. 1. I-V curves of resistivity CO2sensors using pure graphene and Au/graphene, respectively.

Fig. 2. (a) Raman spectra of graphene with and without AuNPs, respectively and (b) XRD spectra of Au metal catalyst decorated on grap.

(3)

∏Œ Œÿ œ◊Ø≥‚ ßÆ∏Œ Á·»Ÿ

[12, 13]. Fig. 2(b)

^¬

Au

° ⁄√» ◊°…«

XRD

^·˙Œ

Au (JCPDS 01-071-4615)

^«

(111), (200), (220)

^◊ÆÌ

(311)

^·§È∫

2

^Ë

= 38.09

^o

, 44.36

^o

, 64.56

^o^◊ÆÌ

77.67

^o° ¢¢ ™∏μ∏Á ◊°…

(JCPDS 03-065- 6212)

^«

(002), (101)

^·§È∫

2

^Ë

= 26.67o, 44.36o

^{°≠ ¢¢ ™∏}

μŸ

.

^{◊°…° ⁄√»}

Au

^{™Î‘⁄« ÷·§È}

(111)

^∫

2

^Ë

= 38.09

^o

°≠ ™∏≠ Õª ÆŒœ¥Ÿ

.

Fig. 3

^∫

10 nm Au

° ⁄√» ◊°…« •Èª

FE-SEM

^ÃÃˆ

Œ À≈Œ≠ ÁÎ»

Au

° ◊°… •È° ¨Ø∫Õ¶ ÃÁˆ Ì

10 nm

« ©‚Œ ÌÁ –˜«˙Ωª ÆŒ“ ˆ ÷Ÿ

.

Fig. 4

^{¬ ¸‚˙◊ƒ}

CO

2°∫æ≠¶

50

^o

C, 500 ppm

^{–ß‚°≠}

Ì¯° «— ›¿ ◊ ª¯° «— ∏π ¿‰ Ø∫ª ›π˚∏Œ ™

∏Ω ÕÃŸ

.

^÷‘»

CO

2¶ ˜‹œ¥ª ÊÏ

, 25

^Ãª°

CO

2° ª¯«˙Ωª À ˆ ÷Ÿ

.

^μ¬

CO

2Ûμ∞ æ≠‚¬ª À ˆ ÷

∏Á ŸΩ« ƒ∏Œ §«œ¥Ÿ

.

©‚≠

, RCO

2¬

CO

2°∫ ÷‘ ƒ« ˙◊ÃÁ

Ra

^¬

CO

2°∫¶

÷‘œˆ ∫ Î‚ﬂ°≠« ˙◊ª ™∏ΩŸ

.

^{¯ˆ ◊°…° Òœ}

©

10nm Au

™Î‘⁄° ⁄√» ◊°…« μ¬ ‡

5

^{Ë §μ Ù∫}

0.24%

^¥Ÿ

. CO

2°∫æ≠« ◊°…∫ §¯Ã Ÿˆ≥ÆÓŒ

p

^∏‘

∏Œ

CO

2° ◊°… •È° Ì¯œÈ

,

Δ°« ›¿ƒ° «ÿ ¸⁄°

ﬂ˝«Ó ˙◊Ã “œ‘ »Ÿ

[3, 14].

Fig. 5

^¬

50

^o

C

^°≠

CO

2Ûμ Ø≠° ˚• ¿‰Ø∫ª ™∏ª¬ Õ

∏Œ ¯ˆ ◊°…˙

Au

° ⁄√» ◊°… Œ

CO

2Ûμ« “° ˚

• ◊°¡« Ø≠¬ —«œ‘ ÆŒ“ ˆ ÷˙∏™

, 10 nm Au

^{° ⁄√}

» ◊°…∫ ‚™∏Œ« Ãø∫ ∏Ãˆ “‚ ßÆ° Ì¯»

CO

2

« œ¸— ª¯∫ ÃÁÓ ˆˆ ∫ Õ∏Œ Á·»Ÿ

. 500 ppm

^°≠

« ¯ˆ ◊°…˙

10 nm Au

° ⁄√» ◊°…« ¿‰√£

(

^÷Î˙◊

«

90%

^{° μﬁœ¬ √£}

)

^{∫ ¢¢}

9

^Õ

28

Œ À≈¶ ÁÎ— ÊÏ°¬

›¿∫« ı°Œ Œÿ ¿‰√£Ã ˆ¨» Õ∏Œ Á·»Ÿ

.

^«—

, 10 nm Au

^{¶ ÁÎ— ÊÏ}

, 2 ppm

« ˙ÛμÓˆ Àˆ °…œ¥Ÿ

.

^˚Û

≠

,

◊°…∫ ≈£« ‚ΩÃ ˚‚ ßÆ° μ¬ ∑ˆ∏

,

^{Í≠∞ Àˆ}

∞˙∏Ÿ∑∫Ûμ«

CO

2Àˆ°°…œŸ

[15].

Fig. 6

∫ Û¬°≠ ¯ˆ ◊°…˙

10 nm Au

° ⁄√» ◊°…° Î

—μ¶™∏ΩÕ∏Œ‚∏°∏Ì»¨∏«ÊÏ°

SnO

2

, ZnO

^Ó

ª ÃÎ—

CO

2°∫æ≠¬ Û¬°≠ ˆ° ÓΔˆ∏

,

^{◊°… ‚›}

CO

2 °∫æ≠¬

500 ppm

^°≠

0.02%

« ∑∫ Ø≠Æª ™∏¬Ÿ

.

›È

, 10 nm Au

° ⁄√» ◊°…« μ¬ øœ Ûμ°≠ ¯ˆ ◊°

Fig. 4. Repeatabilities of response of pure graphene and Au/graphene CO2gas sensors with 500 ppm CO2at 50^oC, respectively.

Fig. 5. Response of CO2sensors with various CO2concentrations at 50^oC.

Fig. 3. SEM image of 10nm Au catalyst decorated on graphene surface.

Response S(%) = R

^CO²

-R

air ^ø

100 (1) R

air

(2) (3) CO

2

(gas) +e-

^Ê

CO

2

-(ads)

CO

2

-(ads) +O-(ads) + 2e-

^Ê

CO(gas) + 2O

2

-(ads)

(4)

…° Òÿ ı°ﬂ∏Á μ« Ø≠Æ∫

500 ppm

^{°≠ ‡}

0.065%

^Œ

¯ˆ ◊°…° Òÿ

3

^{Ë Ù“Ÿ}

.

ÃÕ∫ ¯ˆ ◊°…˙

CO

2« ≠–˚

›¿Ã ≠œˆ ∏Á

Au

^{° «ÿ}

CO

2›¿Ã ‚Û«˙Ωª «Ã—Ÿ

[16].

Fig. 7

∫ ¬μ° ˚• ¯ˆ ◊°…˙

10 nm Au

^{° ⁄√» ◊°…}

« μ¶ ™∏Ω Õ∏Œ ¯ˆ ◊°…« μ¬

100

^o

C

^{œß ‡}

0.182%

Œ °Â Ù∫ μ¶ ∏¥∏Á

, 10 nm Au

^{° ⁄√» ◊°…}

« μ¬

75

^o

C

^{œß ‡}

0.437%

Œ °Â Ù∫ μ¶ ∏ŒŸ

.

^‚∏

SnO

2

, ZnO

Ó Àˆ∞˙ª ÃÎ—

CO

2°∫æ≠¬ ¬μ° ÙΔ˙ˆ œ μ° ÙΔˆ¬ Ê‚ª ∏Ãˆ∏

,

^{◊°… ‚›}

CO

2°∫æ≠¬

Ø§¬μ°≠

CO

2« Ì¯ ›¿ª œˆ∏

,

^{¬μ¶ Ùªˆœ}

CO

2« Ì¯ ›¿Ã ¡ˆ ∫ Õ∏Œ Á·»Ÿ

[5].

4. ·–

ª ¨∏¬ Ò§˙

3C-SiC

≠≥Æ˝∏Œ ’∫— ◊°…¶ ¸Á

— ◊°…˙

Au

™Î‘⁄° ⁄√» ◊°…°

Au

^{¸ÿ¶ ¸∫œ©}

CO

.

^{¯ˆ ◊°… ⁄}

ºŒμ

CO

2Àˆ° °…ﬂˆ∏

,

‡— ›¿∏Œ Œÿ ∑∫ μ

,

^›

¿ ◊ ∏π√£ª ∏¥Ÿ

.

^◊Ø™

, Au

™Î‘⁄ À≈° ⁄√» Ê Ï° μ¬

75

^o

C

^°≠

500 ppm

^«

CO

2μ¶ ‡

4

^{Ë §μ ‚Û}

«˙Ÿ

.

^Ø˜

, Au

À≈¬ ™Î‘⁄ ∏∂Œ ¯ˆ ◊°…∏Ÿ ›¿“

ˆ ÷¬ •È˚Ã –‚ ßÆ° Ù∫ ¿‰ª ∏¥Ÿ

.

˚Û≠

,

ª ¨∏°≠ ¶¤» ◊°… ‚›

CO

2°∫æ≠¬ ‚∏

«

CO

2°∫æ≠« ø¤¬μŒ

200-400

^o

C

« ¸ß° Òÿ ∑∫ ¬

°≠μ ˙Ûμ ¸ß« Àˆ° °…œ‚ ßÆ° ØÊ¿∞ ◊ Ë‚°

∫ Ó« –ﬂ° ¿Î… ˆ ÷ª Õ∏Œ ‚Î»Ÿ

.

Á« ¤

ª ¨∏¬

2012

‚μ Í–˘øÁ‹« Í–˘¬Á˜˙ ﬂ“‚˜

ª« Í–¨¯ø‚˙≥ﬂ Á˜∏Œ ˆ‡«˙¿œŸ

.

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