I

AgI/TiO2

2011 5

AgI/TiO

2 ?????????????????

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II

UDC 10497

AgI/TiO2

Study on Thermochromic Reversibility and Photostability of AgI/TiO2 Nanocomposite

2011 5 2011 5

2011 5

III

:

()

I

AgI 150 oC AgI AgI TiO2AgI/TiO2

1. AgI/ TiO2(P25), AgI/TiO2R AgI/Anatase-TiO2(A)TEM X AgI/ TiO2 TiO2 AgI AgI 150 oC 150 oCAgI/ TiO2(P25) - AgI

2. AgI/TiO2(P25) AgI I-Ag+-I-V-Ag+-I-V-Ag+ AgI TiO2 AgI I- AgI/TiO2 Ag+-O2--Ti4+ AgIAgn AgI/ TiO2

II

Abstract

Pure AgI particles experience a color evolution at the to phase transition

temperature. However, the photoinstability of AgI due to its labile

photodecomposition to metallic Ag under light illumination greatly hinders its

diverse applications. Herein, it was found for the first time that the formation of

AgI/TiO2 nanocomposite not only result in a considerable reduction of

thermochromic transition temperature of AgI as well as excellent thermochromic

reversibility, but also leads to excellent photostability under the illumination of

indoor fluorescent lamp.

AgI/TiO2(P25), AgI/Rutile-TiO2 and AgI/Anatase-TiO2 nanocomposite was

prepared and characterized by transmission electron microscopy (TEM), X-ray

diffraction (XRD) and diffusive reflectance UV-vis (DRUV-vis) absorption spectra

at different temperatures. All the three AgI/TiO2 samples exhibit thermochromic

switching phenomena at the phase - transition temperature of AgI with the

evolution of its color from light yellow at ambient temperature to dark khaki at 150 oC. Besides, the AgI/TiO2(P25) nanocomposite exhibits a hysteresis loop on the

heating/cooling cycle, which is attributed to the suppression of to phase

transition due to the higher surface energy of AgI nano particles.

Based on the characterization results by photoluminescence, transient

photocurrent decay and positron annihilation spectra, it is concluded that large size

surface defects, such as I- vacancy clusters (e.g. Ag+-I-V-Ag+-I-V-Ag+) on the surface

of AgI as deep electron traps, are responsible to photodecomposition of pure AgI.

The excellent photostability for the AgI/TiO2 nanocomposite is due to the following

reason: the surface I- vacancy clusters as deep electron traps in pure AgI are replaced

by Ag+-O2--Ti4+ bonds on the interface of AgI/TiO2, thus Agn cluster formation

through the surface migration of photogenerated Ag atoms is completely inhibited,

resulting in the inhibition of photodecomposition of AgI.

Keywords: AgI, Nanocomposite, Thermochromism, Photostability, Positron annihilation.

III

................................................................................................................................ I Abstract ......................................................................................................................... II ..............................................................................................................................III ..................................................................................................................1

1.1 ......................................................................................1 1.1.1 ....................................................................2 1.1.2 ............................................................2 1.1.3 ....................................................................................3

1.2 ..............................................3 1.2.1 ....................................................................................3 1.2.2 ....................................................................................4

1.3 ......................................................................................6 1.3.1 ........................................................6 1.3.2 ............................................................................7 1.3.3 ............................................................................9

1.4 AgI..................................................................................10 1.4.1 ......................................................................10 1.4.2 AgI....................................................................................12

1.5 ....................................................................13 .AgI/TiO2 .........................................14

2.1 ................................................................................................................14 2.2 ............................................................................................14

2.2.1 ..............................................................................................14 2.2.2............................................................................................15

2.3 ....................................................................................................15 2.3.1 TiO2 ........................................................................15 2.3.2 TiO2 ........................................................................15 2.3.3 TiO2(P25) AgI....................16

2.4 AgI/TiO2 .....................................16 2.4.1 ..........................................................................................16 2.4.2................................................17

2.5.....................................................................................................17 2.5.1...................................................................................17 2.5.2 XRD ................................................................................19 2.5.3 TEM HRTEM ........................................................22 2.5.4...........................................................................23

2.6 ................................................................................................................27 AgI-TiO2............................................................................29

3.1.................................................................................................................29 3.2 ........................................................................................................29

3.2.1 ..............................................................................29 3.2.2 ......................................................................30

IV

3.2 AgI/TiO2 AgI .............................................31 3.3.................................................................................................33 3.4 ........................................................................................35 3.5 ............................................................................39 3.6 ................................................................................................................42

................................................................................................................43 .....................................................................................................................44 ........................................................................................................................48 ..............................................................................................49

1

Feyneman 20 60[1]Feyneman

1nm-100nm[2-9]

[10]

[11]

1.1

2

1.1.1

nanocomposites Roy Kormanrneni[12] 19841-100nm[13]

1.1.2

1.1.2.1

[14]

1.1.2.2

1.1.2.3

3

[15]

1.1.2.4

1.1.3

(1) 10-100nm

10-70m2/g (2)

1063 2nm 300 (3)

(4)

1-0.8 (5) -

5-50nm

(6) 45nm TiO2

1.2

1.2.1

4

[16] GaN/ZnO 1.1ZnO GaN ZnO GaN

1.1 GaN/ZnO

ZnO GaN GaN ZnO ZnO[17]Guo TiO2/ZnO[18] 1 2 3.

1.2.2

[19-21]

5

1.2.2.1

[22] 1.1

1.2

1.2.2.1

[23]

1.3

6

1.3 1 Et 2 Et 1 3 Et 4 Et 3

1.2.2.3

[22]

1.2.2.4

-

[23]

1.3

1.3.1

7

[24],[25]

1871 Houston Houston [26]1959Morin[27-31][32],[33] 80 [34][35] VO2VO2 67 67VO2 VO6 67VO2 VO2

1.3.2

1.3.2.1

8

1.4 25

1.4

1.3.2.2

CuHgI4

[36]

[37](CH3)2CHNH3CuCl 5 6[38] Febinteanu Marilena[Ni(AA)3-n(BB)n][PdX4] Ni2+

9

Cu2+ClAA[Ni(AA)3-n(BB)nCl2][39]

1.3.2.3

CrO42- Pb2+ Pb4+ Pb2+ Pb4+ Pb4+ Pb4+[40] 100

1.3.3

()

10

Del Sol 80 TC Licritherm ,

Nature

1.4 AgI

1.4.1

1925 Sheppard [41][42]

11

TiO2

TiO2[43]

1.5 AgBr/TiO2

1.5 AgBr/TiO2 2.6eV TiO2 3.2eV TiO2Zang TiO2(P25)/TiO2[44]Kakuta/[45]Zhang MX-5B[44]LiAg/AgBr/SFN 7[45]

12

1.6AgI/TiO2 TEM HRTEM

AgI Zhang /[46] Li// AgI/TiO2 Li- 4- 1.6[47]

1.4.2 AgI

AgI, 147 -AgI AgI 147 AgI -AgI-AgI -AgI ABABAB ABCABC

1.5 AgIa-AgIb-AgIc-AgI

147-AgI

13

-AgI[48] -AgI -AgI[49-52] -AgI 1-1cm-1Makiura AgI [53]

1.5

AgI AgI -AgI [49-52] -AgI 1-1cm-1 AgI AgI TiO2 AgI

AgI/TiO2

(1) AgI/TiO2 (2) AgI/TiO2 (3) HRTEMTEMSEMXRD

DRUVPALS

14

AgI/TiO2

2.1

AgI , 147 147-AgI -AgI[48] -AgI -AgI [49-52] -AgI 1-1cm-1Makiura AgI [53] AgI [54-56] AgI AgI

AgI AgI/TiO2 DSCXRDTEM

2.2

2.2.1

15

ECF1-8-13

202-OAB

79-1

KQ-400KDE

TG328A

YZ15W

MC-100l

XQM-0.4

IKAC-MAG HP7

GYZ-125

2.2.2

C16H36O4Ti AR AgNO3 99.5 KI

TiO2(P25) TiO2 AR C2H5OH 99.7

2.3

2.3.1 TiO2

(1) 10.62g TiCl4 200ml

(2) 40 3

(3) 150 TiO2

2.3.2 TiO2

16

(1) (2)

10 (3) 10 200

TiO2

2.3.3 TiO2(P25) AgI

(1) 1.000g TiO2P25 100ml A

(2) 0.078g KI 10ml B (3) 0.080g AgNO3 10ml C (4) B A (5) C A

30 (6) 80

TiO2 TiO2 AgI

2.4 AgI/TiO2

2.4.1

STA449CXXRD Rigaku D/Max-IIIA X Cu KTEM JEM-100CX UV-3600 Shimadzu RF-5301 410 nm X

17

XPert PRO DY2198 X Cu K 10

2.4.2

2-1

(1) AgI/TiO2

(2) (3)

2.5

2.5.1

18

2-2 AgI/TiO2(P25)TG5 /min

2-3 AgI/ TiO2TG5 /min

19

2-4 AgI/ TiO2TG5 /min

2-22-32-4 50TiO2(P25) TiO2 TiO2 AgI 150AgI AgI

2.5.2 XRD

20

2-5 AgI/TiO2 XRD

2-6 AgI/TiO2(P25)XRDa)25 oC, b)70 oC, c)100 oC, d)120

oC, e)140 oC, f)155 oC.

2-7 AgI/ TiO2 XRDa) 25 oC, b) 70 oC, c) 100 oC,

d) 120 oC, e) 150 oC

2-5 AgI/ TiO2 P25 XRDTiO2 PDF

21

83-20450 422.38, 23.70, 39.28, 46.28 -AgI100002(110),(112) AgI/TiO2AgI

2-8 AgI/TiO2XRDa)25 oC, b)70 oC, c)100 oC,

d)120 oC, e)150 oC -AgI -AgI 150 -AgI

XRD 2-62-72-8 AgI/ TiO2 P25AgI/ AgI/ TiO2 XRD AgI/ TiO2 150 -AgI100002 -AgI 150AgI/P25 -AgI100002 -AgI 110200 -AgI 150 -AgI AgI/ AgI/ 150 -AgI -AgIAgI XRD 150 -AgI AgI TiO2-AgI110AgI -AgI110 AgI/AgI/ AgI -AgI110

22

2.5.3 TEM HRTEM

2-9 AgI/TiO2(P25) TEMA HRTEMBAgI/ TiO2 TEMC HRTEMDAgI/ TiO2 TEME

2-9 AgI/TiO2(P25) TEMA HRTEMBAgI/TiO2 TEMC HRTEMD AgI/ TiO2 TEME 2-9A-AgI TiO2TiO2 11-33nm -AgI 10-28mm2-9CTiO2 0.32nm TiO2110 AgI 0.23nm -AgI110

23

AgI/ TiO2 P25 -AgI110/ TiO2110/ TiO2101AgI TiO2(P25)-AgI TiO2110 TiO2(P25) 2-9D D AgI/ TiO2 TEM-AgI

TiO2 TEM AgI/ TiO2 -AgI110/ TiO2101 2-9E AgI/ TiO2 TEMAgI

TiO2-AgI/ TiO2

2.5.4

24

2-10 AgI AgI/TiO2(P25)a) 25 oC, b)

70 oC, c) 100 oC, e) 155 oC.

2-10 AgI/TiO2 AgI 2-11 AgI/TiO2 25 oC100 oC155 oC AgI/TiO2

hv=A(hvEg)1/2

, v, Eg, A[63],[64] AgI/TiO2

25 oC 100 oC 155 oC

2-11 AgI/TiO2