Jurnal f the Krean Chemical Sciety 005, Vl. 49, N. 6 Printed in the Republic f Krea TiO 광촉매활성에서 Rutile 구조의영향 ½ Á k Áy * w yw (005. 8. 5 ) Effect f Rutile Structure n TiO Phtcatalytic Activity Seung-Min Kim, Tae-Kwan Yun, and Dae-Il Hng* Department f Chemistry, Keimyung University, Daegu 704-701, Krea (Received August 5, 005). TiCl4 ƒ ww anatase, rutile ƒ yw TiO Ÿ w. XRD, BET, TEM, XPS UV-Vis DR(Diffuse Reflectance) d mw y w. UV-Vis DR rp rutile rutile anatase ƒ yw TiO anatase TiO Ÿ q w ƒ Ÿ w. ƒ Ÿ w cng red Ÿ w x m w rutile y sƒw. Cng red Ÿ ww rutile anatase ƒ yw ƒ w rutile anatase y ù ùkû. p ƒ Ÿ w cng red ww rutile y w w w, rutile w y k. : ypk, Rutile Fractin, Cng Red ABSTRACT. The TiO phtcatalysts in the anatase, rutile, and bth phases were prepared by the hydrlysis f TiCl 4. The prepared samples have been characterized by pwder x-ray diffractin(xrd), BET, TEM, XPS, and UV-Vis diffuse reflectance spectrscpy. UV-Vis diffuse reflectance spectra shw a slight shift t lnger wavelengths and an extensin f the absrptin in the visible regin fr rutile and rutile/anatase mixtures cmpared t the anatase catalyst. The phtactivity f these catalysts was tested in the phtcatalytic degradatin f cng red diluted in water under UV and Visible irradiatin. It was fund that catalysts f bth phases have better catalytic activity fr degradatin f cng red than anatase and rutile catalysts. The fractin f rutile plays a significant rle in affecting its phtactivity fr phtdegradatin f with ptimum fractin can enhance phtactivity, especially under visible light irradiatin. Keywrds: TiO, Rutile Fractin, Cng Red s s wì ù w w ƒw y š. ù w w» w š y (AOP: Advanced Oxidatin Prcess) w ƒ w š. 1-3 š y w y ƒ OH e g ù w» ww. t š y w O3 HO w O3/UV HO/UVœ 4, (II) HO w Fentn y š 5 TiO Ÿ w TiO/UVœ 1. š y TiO/UV œ w, w, ³, ƒ» z w, ü š 567
568 ½ Á k Áy. w wš Ÿ ƒ 6-8 š anatase TiO 385 nm(3. ev) ƒ y ùk ý x w. 9 w w» w ù 10, j TiO 11 1 vw ƒ Ÿ w» w. ù vw (band gap energy) ƒ Ÿ w y w(electrn hle recmbinatin) g ƒ Ÿ w w TiO w y w 10, 13 š š. Hffmann TiO ù v ù ƒ ƒw y w šw. 10 Zhang TiO Fe 0.09% vw ƒ Ÿ w ww w TiO w y 100% šw. 1 TiO v, v w ƒ Ÿ w y j ùkü š š. 10-1 wz, ƒ ƒ Ÿ y ùkü TiO» y ty ƒ». Rutile TiO ƒ 415 nm(3.0 ev) ƒ Ÿ w y w w anatase TiO w y û š š. w 9 w cng red w w ƒ Ÿ w rutile TiO Ÿ wš ƒ Ÿ y ƒ wš w. x. TiCl4(Aldrich, 99%) ƒ w TiO w. TiCl4» w» ü w» w š ƒ» w. TiCl4 ƒ w w ù j» TiO w» w w w 4 C w ü TiCl4 0.5 M.0 M w g. ƒw y jš, g TiO e. TiO e w» w z w TiO t w. TiO e w» w» w œ l 4 Fig. 1. (a) Phtreactin system and (b) actinmeter. z» x» w 00 C 900 C 3 w w. y x. TiO y sƒw» w» cng red(λmax=496.7 nm) w z w x w š, Fig. 1 ùkü. 7 cm z 1.5 L mx» w. Ÿ š (high pressure mercury lamp, Frce, 300 W) w š, q Fig. ùkü. Ÿ w w» w» y þƒ e ew 5 C w. Jurnal f the Krean Chemical Sciety
TiO Ÿ y Rutile w 569 Fig.. (a) Emissin spectrum f the high pressure mercury lamp and (b) UV-Vis transmissin spectrum f UV-filter. x x 1 L w w š, cng red» 50 mg/l TiO 1.0 g/l w. w cng red yw» w 60 w sx k w x w. y x ƒ Ÿ w w š, ƒ Ÿ Ÿ xw» w l 400 nm w Fig. Ÿ p ƒ vl m g w. Ÿ» l 30 cm w ew z Fig. 1 Ÿ y y w z w x w. z cng red y y w» w w 5 ml w š, TiO ƒ yw w» w 0. µm (membrane filter) w w. UV-Vis Ÿ» cng red d w. y. TiO j» XRD(X-ray Diffractmeter, Philips, X PERT) d w, Cu Kα (=0.154 nm) X Ÿ w z ƒ 0 80 w. XRD d l TiO j» w» w š Si(99.9999%) t w» w sy (line width bradening) w. TiO j» ³ y w» w 100 kv ƒ TEM(Transmissin Electrn Micrscpe, Hitachi, H-7100)d w š, TEM d TiO k k g xw. BET t d w» w t»(surface Area Analyzer, Nva 000) w š,» w sy» ww. d w» w BaSO4 t w UV-Vis Ÿ»(Varian, Cary-50) DR(Diffuse Reflectance) d w. TiO y k y w» w Mg Kα (156.6 ev) X Ÿ k 1s(84.6 ev) vj» vj w 10 trr -9 XPS(X-ray Phtelectrn Spectrscpy, VG Micrtech, MT 500) d w. š Fig. 3» w 00 C 900 C¾ w XRD ql. Fig. 3 400 C w w θ=5.3 anatase(101) p vjƒ d vj ƒ û š, x TiOƒ w ùkü. ƒ 400 C anatase p vj ƒ ƒw š, ƒ 750 C θ=7.5 rutile(110) p vjƒ d. TiOƒ anatase rutile 750 C w ùk ü. 900 C TiO k anatase vj x d š, k rutile vj d. Fig. 3 Fig. 4 XRD d l TiO rutile (1) w w. (1) X TiO rutile ùküš I A I R ƒƒ 005, Vl. 49, N. 6
570 ½ Á k Áy θ=5.3 anatase θ=7.5 rutile XRD p vj ùkü. 14 X 1 0.8I A + ----------- 1 = I R Kλ L = ( ------------------ βcsθ) (1) () Fig. 3. XRD patterns f TiO particles calcined at (a) 00 C, (b) 400 C, (c) 700 C, (d) 750 C, (e) 800 C, and (f) 900 C. Fig. 4. XRD patterns f TiO particles calcined at 400 C: (a) Ti1, (b) Ti, (c) Ti3, (d) Ti4, and (e) Ti5. j» Fig. 3 Fig. 4 anatase rutile vj s () Scherrer w w. () L TiO j», λ x X-ray q (Cu Kα=0.154 nm) š K 0.9, β XRD vj es» w sy w. (1) () w TiO Ÿ rutile j» Table 1 ùkü. Table 1 j» rutile w ƒw š, BET t ƒ w w y w. w TiO Table 1 j» BET t j. Ÿ j» BET t w ywš ƒ Ÿ Ÿ ƒ y w w y wš 400 C TiCl4 w rutile ƒ TiO w. Fig. 4 TiCl4 w rutile ƒw y w. TiCl4 ƒ ƒw Table 1. Summary f the prperties and calcinatin cnditins f TiO Sample Calcinatin Rutile Crystallite size(nm) BET Surface area Degradatin f cng red(%) a temperature( C) fractin(%) Rutile Anatase (m /g) UV Visible Ti11 00 0-7.7 60.1 - - Ti1 400 0-11.0 137.9 74.1 31.7 Ti 400 17 1.0 9.3 16.6 89.3 56.3 Ti3 400 59 1. 11.9 75.7 86.0 44.6 Ti4 400 91 16. 11.4 78.3 75.0 37.8 Ti5 400 100 1.8-78.9 7.4 37.6 Ti1 700 0-58.7 1.5 - - Ti13 750 17 160.3 93.3 5.7 1.7 10.9 Ti14 800 98 185.5 17.6 1.4 16.8 9. Ti15 900 100 57.1-1.1 15.8 9.4 a After phtdegradatin f cng red fr 60 min, exclusive f equilibrium adsrptin. Jurnal f the Krean Chemical Sciety
TiO 광촉매 활성에서 Rutile 구조의 영향 571 Fig. 5. TEM images f TiO particles calcined at (a) 00 C, (b) 400 C, (c) 600 C, and (d) 800 C. 식 (3), (4) 및 (5)와 같이 부산물로써 H 가 생성되며, H 의 농도가 높아지면 700 C이상의 열을 가해주지 않아도 anatase 구조가 재배열하여 rutile 구조로 상전 이하게 된다. Table 1에 TiCl 농도에 따른 TiO 의 입자크기, rutile 분율 및 BET 표면적을 나타내었다. + + 15,16 4 TiCl4 + HO TiOH3++H++4Cl TiO++H+ TiOH3+ + TiO(hydrus)+H+ TiO +HO (3) (4) (5) 소성온도 및 TiCl 농도에 따른 TiO 의 입자크기 및 분포를 확인하기 위해 TEM을 측정하였고, Fig. 5에 나타내었다. XRD 측정에서와 같이 소성온도가 높아 질수록 입자크기가 증가하였다. 그러나 동일한 소성 온도에서 제조한 촉매는 rutile 분율에 따른 입자크기 및 분포의 변화가 TEM 측정에서 구별되지 않았다. 결정구조에 따른 TiO 의 결합상태를 확인하기 위해 XPS를 측정하였고 Fig. 6에 나타내었다. 결정구조와 관계없이 티타늄의 p 및 p 피크는 각각 463.6 ev 및 457.6 ev에서 나타났고 산소의 1s 피크는 59.0 ev 4 1/ 005, Vl. 49, N. 6 3/ Fig. 6. XPS spectrum f TiO calcined at 400 C. 에서 나타났다. TiO 는 결정구조에 따라 anatase의 띠 간격 에너지는 385 nm(3.0 ev)이며 rutile은 415 nm(3.0 ev)로 알 려져 있다. 본 연구에서는 rutile 분율에 따른 촉매의 띠 간격 에너지 변화를 확인하기 위해 순수한 anatase 및 rutile 분율이 17%에서 100%인 TiO 의 UV-Vis DR 9
57 ½ Á k Áy Fig. 7. UV-Vis diffuse reflectance spectra f TiO with different rutile fractin. d w. Fig. 7 rutile ƒw Ÿ q (red shift) w y w š, w rutile w. w rutile ƒ TiO w Ÿ p y w š, Ÿ q š 30 nm¾. y g w TiO w 50 mg/l cng red ƒ Ÿ w w x w. Fig. 8 Fig. 9 ùkü ƒ ƒw y w. w x rutile Fig. 8. Phtdegradatin f cng red ver TiO with different rutile fractin calcined at (a) 400 C (pure anatase), (b) 750 C (17% rutile), (c) 800 C (98% rutile), and (d) 900 C (100% rutile) under UV illuminatin. Fig. 9. Phtdegradatin f cng red ver TiO with different rutile fractin calcined at (a) 400 C (pure anatase), (b) 750 C (17% rutile), (c) 800 C (98% rutile), and (d) 900 C (100% rutile) under visible illuminatin. w» Table 1 ƒ w y e w j» ƒ BET t» w. TiO ƒ (valence band) (cnductin band) y(h + ) (e ) - w. TiO w Ÿ w y w t, y BET t w. rutile TiO w BET t w y w rutile w y y y w. BET t w y w y wš rutile ƒ Ÿ y w w y w» w 400 C w rutile 0%, 17%, 59%, 91% 100% TiO w. TiO w 50 mg/l cng red w x w. Fig. 10 w anatase rutile sww TiO y ûš, 60 Ÿ k rutile 17% 59% w wš ƒ w anatase w cng red ƒƒ 0.5% 16.1% û. Ÿ rutile 91% w anatasex w y š, rutile 100% w anatasex Jurnal f the Krean Chemical Sciety
Fig. 10. Phtdegradatin f cng red ver TiO with different rutile fractin calcined at 400 C under UV illuminatin. TiO Ÿ y Rutile w 573 sww anatase y j. ù y TiO rutile w š, rutile e y w w y w. w anatasex TiO ƒ 385 nm, Fig. 11 ƒ Ÿ w y ùkþ. w x TiO t cng red k ƒ ƒ Ÿ w k TiO w š ƒ y g (11) (1) OH e 17, 18 w cng red w j». w anatase TiO ƒ Ÿ w y cng redƒ Ÿ (phtsensitizer) w y ùkü. Fig. 11. Phtdegradatin f cng red ver TiO with different rutile fractin calcined at 400 C under visible illuminatin. y ùkû. vl ew ƒ Ÿ w w 50 mg/l cng red w x w š, Fig. 11 ùkü. w xw w rutile w w y w anatasex ù ùkû. ù ƒ Ÿ w 50 mg/l cng red 60 Ÿ w j w anatase w rutile 17% y ƒ Ÿ w ƒƒ 0.5% 77.6% Ÿ y j. Table 1 rutile sww ƒ w anatase w BET t Ÿ y. p ƒ Ÿ Ÿ rutile * CR(Cng Red)ads + hv CRads (6) * CRads +TiO CRads + +TiO(e ) (7) TiO(e )+O TiO+O (8) O +H + ΗΟ +Ο +Η + Η O+O (9) O +H + +ΤiΟ (e ) Η O+TiO (10) Η Ο +Ο ΟΗ +OH +O (11) Η O+TiO(e ) ΟΗ +OH +TiO (1) Asahi 19 Zhang 1 w TiO vw ƒ Ÿ q v w q w» e v y w j šw. rutile w w TiOƒ Fig. 7 rutile w w 400 nm 415 nm¾ ƒ Ÿ w š w anatasex TiO w ƒ Ÿ w y { û. ù Fig. 11 ƒ Ÿ w rutile y w rutile ƒw q w BET t wš y w ƒ» q. TiO Ÿ y rutile w š w» w w rutile TiO 005, Vl. 49, N. 6
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