EL ECTROCHEMISTR Y ( PAN I) 3. 0 ev ev,. Mott2Schottky mol/ L K 3 Fe (CN) 6 / K 4 Fe (CN) 6 (p H = 8. 52) : A. ]. PAN I

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1 EL ECTROCHEMISTR Y Vol 7 No 1 Feb 2001 :1006Ο3471 (2001) 01Ο0102Ο07 TiO 2 2,,,, (,, ) 3 : TiO 2 2 ( PAN I) TiO 2 PAN I, TiO 2,, TiO 2 PAN I TiO 2 TiO ev Fowler ( g 1/ 2 h ) Fowler 3 33 ev, Mott2Schottky 0 05 mol/ L K 3 Fe (CN) 6 / K 4 Fe (CN) 6 (p H = 8 52) 0 13 V, cm - 3 ; TiO 2 2 PAN I V, cm - 3 TiO 2 2PAN I TiO 2 2PAN I : TiO 2 ; ; : O 646 : A Grgetzel [1,2 ], [3 ], TiO 2, [4 ( PAN I) ] PAN I [5,6 ev, ], [7 ] TiO 2 2PAN I,, TiO 2 2PAN I 1 1 1,PAN I/ PA TP/ Au : ( PA TP) PA TP/ Au [8 ] PA TP/ Au ( 0 41 cm 2 ),0 5 mol/ L / 0 5 mol/ L HClO 4, : : ( , ), (99177)

2 1 : TiO V (, ) 100 mv/ s, 125, m PAN I/ PA TP/ Au 1 0 mol/ L HClO V 10 min, PAN I/ PA TP/ Au TiO 2 2PAN I PAN I/ PA TP/ Au, NaOH p H (p H2 2),+ 0 1 V 30 min, 1 2 CHI2660 ; HITACHI S2520 [9 ; ], RkP576a Rk Hz (, g ) 2 (model 2100, Kyoto) (20 ) 2 1 (a) (b) PAN I TiO 2 2PAN I, PAN I, PAN I TiO 2 PAN I, PAN I 1 PAN I (a) TiO 2 2PAN I (b) SEM Fig 1 SEM micrograph for PAN I film(a) and TiO 2 2PAN I composite film(b) 3 2 TiO 2 2PAN I PAN I 0 05 mol/ L Fe ( CN ) - 6 / Fe 4 (CN) - 6 PAN I TiO 2,0 7 V TiO 2 2PAN I

3 nm450 nm 400 nm300 nm, 0 V 730 nm450 nm 730 nm450 nm PAN I,400 nm300 nm TiO 2 TiO 2 PAN I TiO ev PAN I TiO 2, TiO 2 2PAN I 350 nm 550 nm, 6 1 W 4 4 W, g % 2 TiO 2 2PAN I/ PA TP/ Au PAN I/ PA TP/ Au 0 05 mol/ L K 3 Fe ( CN) 6 / K 4 Fe %( ) (CN) 6 TiO 2 2PAN I, Fig 2 Photocurrent spectra of TiO 2 ΟPAN I/ 3,0 05 mol/ L Fe (CN) / Fe (CN) - 6 PA TP/ Au and PAN I/ PA TP/ Au film, electrode in 0 05 mol/ L K 3 Fe ( CN 6 ) / K 4 Fe (CN) ( 3 ) 6 solution 552 mv 22 76A, 0 84, Fe ( CN) / Fe ( CN) 6 4 -, 2 4 %, Fowler,4 PAN I Fowler g 1/ 2 = A (h 2 E t ), ( E t,h ), 4,,A 3 TiO 2 2PAN I/ PA TP/ Au a b x K 3 Fe (CN) 6 / K 4 Fe (CN) 6 Ο, 1 69 ev 1 64 ev Fig 3 PhotocurrentΟvoltage characteristics of a cell, based on the TiO 2 2PAN I/ PA TP/ Au film elec2 trode and the electric couple of K 3 Fe ( CN) 6 / E g = 3 33 ev [10 ], K 4 Fe (CN) 6 PAN I,

4 1 : TiO mol/ L K 3 Fe ( CN ) 6 / K 4 Fe( CN) 6 (p H = 8 52) PAN I PAN I TiO 2, 1 0 mol/ L HClO 4 (p H = 0 43, ) ( f = 1 000Hz), Mott2Schottky ( 5 ), Mott2Schottky 1/ C 2 = ( E - E fb - k T/ q) /N (, q, N,, k, T ) [11 ], 1 0 mol/ L HClO 4 4 PAN I < 1/ 2 h PAN I 0 63 V,TiO 2 Fig 4 < 1/ 2 versus hplot derived from photocurrent V p H spectra of partiallyοoxidized PAN I [12 ], 0 05 mol/ L K 3 Fe (CN) 6 / K 4 Fe (CN) V V 5a, PAN I p 5b PAN I TiO 2 n 5 PAN I TiO cm - 3 (= 22 5 [13 ] ) cm - 3 (= 50 [14 ] ) TiO 2 PAN I, SEM, TiO 2 2PAN I ( 6 ) PAN I TiO 2, TiO 2 PAN I, / V,PAN I PAN I 2 TiO 2 TiO 2 2 ;TiO 2 TiO 2 2 PAN I TiO 2 PAN I [7 ], 730 nm450 nm 400 nm300 nm 0 V, /, PAN I 2,PAN I PAN I 2 TiO 2 TiO 2 2, PAN I PAN I Au, 730 nm450 nm, PAN I ( PAN I), cm - 3 ( ) [7 ],, ( )

5 Tab 1 The result of photodegradation for phenol solution(100 mg/ L) Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Illuminating time/ min Absorbance Concentration/ mg L Degradation efficiency TiO 2 2PAN I, 442 3W, 2 mm 30 ml 100 mg/ L, 30, 60,90,120,150 min,, 1 TiO 2 2 PAN I 3 PAN I TiO 2, TiO 2 PAN I PAN I TiO 2,0 7 V TiO 2 2 PAN I 730 nm 450 nm 400 nm300 nm, 0 V 730 nm450 nm TiO 2 PAN I, 5 PAN I TiO 2 ΟPAN I TiO mol/ L HClO 4 (p H = 0 43) MottΟSchottky TiO ev Fig 5 Mott ΟSchottky plots for partiallyοoxidized PAN I film ( A) and TiO 2 ΟPAN I composite Fowler PAN I film (B) in the 1 0 mol/ L HClO 4 solution(p H = 0 43) Fowler

6 1 : TiO ev, Mott2Schottky 1 0 mol/ L HClO 4 PAN I 0 87 V (N HE), cm - 3 TiO 2 2PAN I 0 09V (N HE), cm - 3 PAN I p, PAN I TiO 2 n TiO 2 2PAN I 6 TiO 2 ΟPAN I Fig 6 Energy diagram of the simplified band structure of the TiO 2 ΟPAN I composite film The Photoelectrochemistry of TiO 2 2Polyaniline Composite Film HUAN G Huai2guo,ZHEN G Zhi2xin, L UO jin, ZHAN G Hong2ping, WU Ling2ling, L IN Zhong2hua 3 ( S tate Key L ab f or Phys Chem of the Solid S urf ace, Dept of Chem, Inst of Phys Chem, Xiamen U niv, Xiamen, , China) Abstract : A TiO 2 and polyaniline ( PAN I) composite film was obtained by electrochemical methods The SEM image of the composite film showed that the PAN I film is almost completely covered with TiO 2 The spectra of photocurrent for the TiO 2 2PAN I composite film, which over2 laps the TiO 2 film and PAN I film, showed that the composite film is able to have higher conver2 sion efficiency The spectra of photocurrent for the TiO 2 2PAN I composite film were different from these of TiO 2 film photosensitized by PAN I The bandgap energy of TiO 2 film on partially2 oxidized PAN I film was determined as 3 0 ev by the threshold energy of photocurrent band for TiO 2 The spectra of photocurrent for partially2oxidized PAN I film electrode suggested that it has the characteristics of sub2band gap spectra of photocurrent and followed Fowler rule( g 1/ 2 h ) The bandgap energy of insulating matrix in partially2oxidized PAN I is determined as 3 33 ev by the Flowler plots, and the insulating matrix in partially2oxidized PAN I was verified to be reduced

7 PAN I The flat2band potentials, in the order of 0 87 V vs N HE for partially2oxidized PAN I and 0 09V vs N HE for TiO 2 2PAN I composite film in 1 0 mol/ L HClO 4 solution,were obtained from Mott2Schottky plots The doping content of partially2oxidized PAN I and TiO 2 2PAN I composite film are cm - 3 and cm - 3, respectively The photoelectrochemical process of TiO 2 2PAN I composite film is interpreted and the energy diagram is proposed The TiO 2 2PAN I composite film can be well used for treating the wastewater, for example, containing phenol Key words : TiO 2, Polyaniline, Photoelectrochemistry Reference s : [1 ] O Regan B, Grgtzel M A low2cost, high2efficiency solar cell based on dye2sensitized colloidal TiO 2 films [J ] Nature, 1991, 353 :737 [2 ] Nazeeruddin M K, Kay A, Rodicio I et al Conversion of light to electricity by cis2x2bis ruthenium( II) [J ] J Am Chem Soc, 1993, 115 :6 382 [3 ] Vogel R, Hoyer P, Weller H Quantum2sized PbS,CdS,Ag 2 S,Sb 2 S 3 and Bi 2 S 3 particles as sensitizers for various nanoporous wide2bandgap semiconductors[j ] J Phys Chem, 1994, 98 :3 183 [ 4 ] Kilmartin P A, Wright G A Anion insertion and expulsion in polyaniline electrodes studied by photocur2 rent transients[j ] Electrochim Acta, 1998, 43 : [ 5 ] Stafstrom S, Bredas J L, Epstein A J, et al Polaron lattice in highly conducting polyaniline : theoreti2 cal and optical studies[j ] Phys Rev Lett, 1987, 59 : [ 6 ] McCall R P, Grinder J M, Leng J M, et al Spectroscopy and defect states in polyaniline[j ] Phys Rev B, 1990, 41 : [7 ] Zuo F, Angelopoulos M, MacDiarmid A G, et al Transport studies of protonated emeraldine polymer : a granular polymeric metal system[j ] Phys Rev B, 1987, 36 : [8 ] ZHAN G Hong2Ping, LUO2Jin, HUAN G Huai2Guo, et al Ordered Nano2structured polymer films of PA TP/ PAN I by electrochemical2assembly[j ] Chem J Chinese Universities, 1999, 20 :624 [9 ] LUO2Jin, L IN Zhong2Hua, WU Ling2Ling, et al In situ electronic spectroscopic techniques for interfacial electrochemistry[j ] Chem Research in Chinese Univ, 1996, 12 : 270 [ 10 ] Sukamto J P H, Mcmillan C S, Smyrl W H Photoelectrochemical investigations of thin metal2oxide films : TiO 2,Al 2 O 3 and HfO 2 on the parent metals[j ] Electrochim Acta, 1993, 38 : 15 [11 ] Bard A J, Faulkner L R Electrochemical methods : fundamentals and applications[ M ] Wiley, New York : [12 ] Fujishima A et al Electrochemical mensuration [ M ] Beijing : Peking University s Printing House, [13 ] Schrebler R, Gomez H, Cordova R et al Study of the aniline oxidation process and characterization of pani films by electrochemical impedance spetroscopy[j ] Synth Met, 1998, 93 : 187 [14 ] Goossens A Intensity2modulated photocurrent spectroscopy of thin anodic films on titanium [J ] Surf Sci, 1996, 365 : 662