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1 Journal of Korean Powder Metallurgy Institute Vol. 17, No. 4, 2010 DOI: /KPMI w k v ƒ Ÿ y Ÿ p sƒ Á a * w» l œw, a ( ) lj qj, ù t» Preparation of C Doped Photocatalyst Activating to Visible Irradiation and Investigation of Its Photocatalytic Activity In-Chul Yeo and In-Cheol Kang a Department of Mechanical Engineering, Incheon University, Incheon , Korea a Department of Nano-Surface Technology, SongdoTechnopark, Incheon , Korea (Received June 9, 2010; Revised June 24, 2010; Accepted July 2, 2010) Abstract A carbon doped (C- ) photocatalyst, which shows good photocatalytic activity to Ultraviolet irradiation and visible irradiation, was successfully prepared by co-grinding of with ethanol or Activated Carbon(C), followed by heat treatment at 200 o C in air for 60 min. Ethanol and C were used as a representative agent of liquid and solid for carbon doping. Their influence on improving photocatalytic ability and carbon doping degree was studied with degradation of methyl orange and XPS analysis. The product prepared by co-grinding of with Ethanol had Ti-C and C-O chemical bonds and showed higher photocatalytic activity than the product prepared by co-grinding of with C, where just C-O chemical bond existed. As a result, mechanochemical route is useful to prepare a carbon doped photocatalyst activating to visible irradiation, where the solid-liquid operation is more effective than solid-solid operation to obtain a carbon doped. Keywords :, Carbon doping, Mechanochemical, Photocatalyst 1.»/ ü w w, w, k Ÿ» yw y j, x ƒ w š [1-5]. p, Ÿ w w üyw Ÿ Ÿ ƒ Ÿ š [1, 6, 7]. ù Ÿ y w. k Ÿ 3-5% wš ƒ Ÿ 48% wš. Ÿ ƒ ƒ Ÿ w y k Ÿ z y w, w y w Ÿ y w Ÿ y ƒ y». ƒ Ÿ y Ÿ» w wy[8], t [9], y[10] w w, p ù vw y ƒ w [11-16]., k, y v w ü O2p ƒ C2p/N2p/S3p e w ˆ ƒ, ƒ Ÿ w y» Ÿ y ƒ w. k vw» w mechanochemical(mc) w. MC mw yw» *Corresponding Author : [Tel : ; [email protected]] 281

2 282 Á yw yw w, û yw w w œ [17]. k vw ƒ Ÿ y Ÿ w» w k ƒ y w ƒ w. wù k wù š y k. ƒƒ w w y,, t, Ÿ p y, k v, yw w y w Ÿ p w w w e, w œ y w sƒwš w. 2. x 1 x œ ùkü. œ w (HAJI ENG., Korea) w, w ü vƒ 45 cm 3 y g sp(psz) 15 mm g 7 w. anatase- (a- ; purity-min 98.5%, Wako Pure Chem. Inc., Japan) w, k w w y w ƒƒ k y k w. k v w w g sp g 7 ( 4g) wì š 700 rpm ¾ w. w z z w» 200 o C 60 w œ w t w w. ƒ 400 o C v k y w» 200 o C w [18]. k yw ƒ y ww» w Cu-Ka w XRD (RAD-B, Rigaku Co. Ltd., Japan) w w, t (SSA) w» w k d (ASAP- 2010, Micrometritics, Shimadzu Co. Ltd., Japan) w. k v q w» w X- ray photoelectron spectroscopy(xps)(phi5600 ESCA system, Ulvac-phi. Inc., Japan) w k y w w w. Ÿ p sƒ w ƒ Ÿ ƒ p w sƒw [19]., k yw ƒ k Fig. 1. Experimental flowing chart for preparation of C doped by mechanochemical process. Journal of Korean Powder Metallurgy Institute

3 w k v ƒ Ÿ y Ÿ p sƒ 283 yw ƒƒ w 0.2 g» ƒƒ š, 5 ppm p 100 ml» z ƒ Ÿ Ÿ w g ¾ p y d w. d w w UV-Visible Spectrophotometer (DU-800, Beckmn Coulter, USA) w p d w. 3. š 2 anatase- (a) k ƒ v (C- )(b) ˆ yw. k ƒ v anatase- 3.2 ev ˆ ƒ w y».» (excited electron) (conduction band) w z y w wš ù t w y k.» y(hole) ƒ (valence band) û w wš t w y w. k ƒ v C2p ƒ x w O2p ˆ w. Ÿ ƒ Ÿ w y». k ƒ v ƒ Ÿ w y» k ƒ Ÿ z w w Ÿ yw» w. 3 + k (A) +C(B) w z y XRD Fig. 2. Schematic diagrams for band-gap structure of raw- (a) and C doped (b). Fig. 3. Phase constitution with period of grinding time for +ethanol (A) and +C (B). Vol. 17, No. 4, 2010

4 284 Á w. 3 A, R, S ƒƒ anatase, rutile srilankitex ùkü, Z ball pot w ¼ ZrO 2 ùkü. 3(A) (a)» anatase ùkü. 15 w š x srilankite (high pressure phase) x, ¼ Rutile w, 240 w anatase srilankite rutile w.» ƒ y w y y w, œ w [19]. +C(B) ƒ œ ¼ rutile w, (A) ZrO 2 ƒ. š +š š + ball pot f ƒ w». š x 12, NH 3» w ZrO 2 ƒ. š ZrO 2 ball w ball w ZrO 2 ball ZrO 2 pot» q. ù ƒ ƒ w ball w ZrO 2 ball w f j ƒ w. 4 k (5 wt%) yw w w t y ùk ü. 10 m 2 /g ¼ t ƒw 120 w 53 m 2 /g ¾ ƒw. w y w» œ w k v w. š x 18 š w w [18], 120 w k wì 120 w t w, w j» k wì w t w w 5 ù j. k ƒ w, i) k ƒ w k v w, ii) k ƒ w k q. œ x g t k. ù 240 ¾ ¼ wš v w ƒ t w š š ƒ k t w w w» [18]. 5 k 700 rpm 120 w t y k ƒ ùkü. 4 w w š. (a) k ƒ w š 120 w. Fig. 4. Specific surface of +ethanol(5gwt%) ground by 700G rpm with change of period of grinding time. Fig. 5. Specific surface area of +ethanol ground by 700Grpm for 120Gmin with change of added ethanol amount. Journal of Korean Powder Metallurgy Institute

5 유성 볼밀법을 이용한 탄소 도핑 가시광 활성 값은 볼밀 하기 전인 초기 분말의 비표면적 값과 거 의 같았다. 이는 비표면적의 증가는 볼밀에 의한 분 말의 미세화 보다는 탄소 도핑으로 인한 표면 개질 에 의해 비표면적이 증가하는 것임을 잘 설명해 준 다. 첨가되는 에탄올의 양이 증가하면서 비표면적의 TiO 2 광촉매 제조 및 이의 특성 평가 285 값이 증가하는 양상을 잘 보여준다. 9 wt%의 에탄올 을 첨가했을 경우 약 59 m /g까지 비표면적이 증가했 으나 10 wt% 이상의 에탄올을 첨가한 경우에는 과다 첨가로 인해 볼밀이 진행되기 어려울 정도로 분말들 간의 응집 현상이 일어났다. 2 Fig. 6. SEM images of raw-tio2(a) and samples(b-d) ground by 700 rpm for 120 min with change of added ethanol amount. Fig. 7. Photocatalytic activity of TiO2+ethanol(5 wt%) ground by 700 rpm with change of grinding period of time to visible (A) and UV (B) irradiation; Horizontal axial (the period of irradiation), Vertical axial (a residual amount of methylorange); (a) ethanol(5 wt%)-15 min grinding, (b) ethanol(5 wt%)-30 min grinding, (c) ethanol(5 wt%)-60 min grinding, (d) ethanol(5 wt%)-120 min grinding and (e) as received TiO2. Vol. 17, No. 4, 2010

6 286 Á 6 k ƒ SEM. (a)» 30 µm xk š. (b)-(d) ƒƒ 0wt%, 3 wt%, 5 wt% ƒw 700 rpm 120 w z SEM. (b)-(d) j š. k ƒw (c) (d) (b) w x û ƒ. w t 10 m 2 /g 53 m 2 /g j» k v w. š x 23 k ƒ v w t ƒw š šwš, k ƒ v w ƒ y w» š šw [23]. 7 + k (5 wt%) 700 rpm w z ƒ Ÿ Ÿ (X ) p (Ÿ p, Y ) y d w. (A) ƒ Ÿ w p y š (B) w. (a)-(d) ƒƒ 15, 30, 60, 120 w w ùkü, (e)» anatase- w. ƒ Ÿ Ÿ p ƒ w w. p, 60, 120 w 15, 30 w x w Ÿ w. anatase- (e) w š. w (B) ƒ Ÿ (A) w w, ¼ w w. ¼ k v z ƒ w». 8 + k 700 rpm 120 w, k ƒ (5 wt% (a), 7 wt% (b), 9 wt% (c)) p (Ÿ w ; Y ) Ÿ k (X ) ùkü. ƒ Ÿ k 5 wt% (a) ƒ w Ÿ p ƒ, 7 wt% (b) 9wt% (c) û w. 7wt% (b) 9wt% (c)ƒ 5wt% (a) w t f ( 5) ew w. ƒ k ƒw k v w t t ƒw. ù k v ˆ w» y w ƒ g Ÿ p û [20, 21]. w k 5wt% ƒw š Ÿ p w w ˆ ƒ f w k ƒ. Fig. 8. Photocatalytic activity of +ethanol ground by 700Grpm with change of added ethanol amount to visible (A) and UV (B) irradiation; Horizontal axial (the period of irradiation), Vertical axial (a residual amount of methylorange); (a) ethanol(5g wt%)-120g min grinding, (b) ethanol(7g wt%)-120g min grinding, (c) ethanol(9g wt%)-120 min grinding and (d) as received. Journal of Korean Powder Metallurgy Institute

7 w k v ƒ Ÿ y Ÿ p sƒ 287 Fig. 9. Photocatalytic activity of +C ground by 700Grpm with change of grinding period of time and added C amount to visible(a) and UV(B) irradiation; Horizontal axial (the period of irradiation), Vertical axial (a residual amount of methylorange); (a) C(5Gwt%)-15Gmin grinding, (b) C(5Gwt%)-30Gmin grinding, (c) C(5Gwt%)-60Gmin grinding, (d) C(5Gwt%)-120 min grinding, (e) C(1G wt%)-120g min grinding, (f) C(3G wt%)-120g min grinding and (g) As received Carbon. 9 +C ƒ k ƒ Ÿ (A) (B) Ÿ w (X ) Ÿ p (Y : p ) sƒw. (a)-(d) k 5wt% ƒ z 700 rpm 15, 30, 60, 120 w w š, (e) (f) 1 wt%, 3 wt% k ƒw k 700 rpm 120 w w. (g) k v w ƒ w k w. ¼ p ƒw w š. wr,» k w 30 ü p ƒ.» k p w š, k ƒ p. (A) (d), (e), (f) w w š. š ¼ p ƒw w k y w p w k œ ƒ q». x ƒ Ÿ š. ù 9 ü k v w Ÿ z w y w w š, 10 w. 10 C1s w t yw w Fig. 10. Chemical binding energy of C1s; (a) +ethanol(5gwt%), (b) +C(5Gwt%) and (c) as received. ùkü. (a) (b) ƒƒ + k (5 wt%) +C(5 wt%) 700 rpm 120 z 200æ 60 w. anatase- (c) ev C-C w š» k ƒ t [22]. Vol. 17, No. 4, 2010

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