Abstract:Photocatalytic reduction of CO2 on TiO2 and Cu/TiO2 photocatalysts was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) under UV irradiation. The photocatalysts were prepared by sol-gel method via controlled hydrolysis of titanium (IV) butoxide. Copper precursor was loaded onto TiO2 during sol-gel procedure. A large amount of adsorbed H2O and surface OH groups was detected at 25°C on the TiO2 photocatalyst after being treated at 500°C under air stream. Carbonate and bicarbonate were formed rapidly due to the reaction of CO2 with oxygen-vacancy and OH groups, respectively, on TiO2 surface upon CO2 adsorption. The IR spectra indicated that, under UV irradiation, gas-phase CO2 further combined with oxygen-vacancy and OH groups to produce more carbonate or bicarbonate. The weak signals of reaction intermediates were found on the IR spectra, which were due to the slow photocatalytic CO2 reduction on photocatalysts. Photogenerated electrons merge with H+ ions to form H atoms, which progressively reduce CO2 to form formic acid, dioxymethylene, formaldehyde and methoxy as observed in the IR spectra. The well-dispersed Cu, acting as the active site significantly increases the amount of formaldehyde and dioxymethylene, thus promotes the photoactivity of CO2 reduction on Cu/TiO2. A possible mechanism of the photocatalytic CO2 reduction is proposed based on these intermediates and products on the photocatalysts.
出版日期: 2010-06-05
引用本文:
. In situ DRIFTS study of photocatalytic CO 2 reduction under UV irradiation[J]. Front. Chem. Sci. Eng., 2010, 4(2): 120-126.
Jeffrey C. S. WU, Chao-Wei HUANG, . In situ DRIFTS study of photocatalytic CO 2 reduction under UV irradiation. Front. Chem. Sci. Eng., 2010, 4(2): 120-126.
Tseng I H, Chang W-C, Wu J C S. Photoreduction of CO2 using sol-gel derived titania and titania-supported copper catalysts. Appl Catal B: Environm, 2002, 37(1): 37―48 doi: 10.1016/S0926-3373(01)00322-8
Ulagappan N, Frei H. MechanisticStudy of CO2 Photoreduction in Ti silicalitemolecular sieve by FT-IR spectroscopy. J Phys Chem A, 2000, 104(33): 7834―7839 doi: 10.1021/jp001470i
Bando K K, Sayama K, Kusama H, Okabe K, Arakawa H. In-situFT-IR study on CO2 hydrogenation over Cu catalystssupported on SiO2, Al2O3, and TiO2. Appl Catal A: Gen, 1997, 165(1―2): 391―409 doi: 10.1016/S0926-860X(97)00221-4
Yang R, Fu Y, Zhang Y, Tsubaki N. Insitu DRIFT study of low-temperature methanol synthesis mechanism onCu/ZnO catalysts from CO2-containing syngasusing ethanol promoter. J Catal, 2004, 228(1): 23―35 doi: 10.1016/j.jcat.2004.08.017
Schilke T C, Fisher I A, Bell A T. In situInfrared study ofmethanol synthesis from CO2/H2 on titania and zirconia promoted Cu/SiO2. J Catal, 1999, 184(1): 144―156 doi: 10.1006/jcat.1999.2434
Nomura N, Tagawa T, Goto S. In situ FTIR study on hydrogenationof carbon dioxide over titania-supported copper catalysts. Appl Catal A: Gen, 1998, 166(2): 321―326 doi: 10.1016/S0926-860X(97)00271-8
Wu J C S, Cheng Y-T. In situ FTIRstudy of photocatalytic NO reaction on photocatalysts under UV irradiation. J Catal, 2006, 237(2): 393―404 doi: 10.1016/j.jcat.2005.11.023
Tseng I H, Wu J C S, Chou H-Y. Effects of sol-gel procedures on thephotocatalysis of Cu/TiO2 in CO2 photoreduction. J Catal, 2004, 221(2): 432―440 doi: 10.1016/j.jcat.2003.09.002
Liao L F, Lien C F, Shieh D L, Chen M T, Lin J L. FTIR study of adsorptionand photoassisted oxygen isotopic exchange of carbon monoxide, carbondioxide, carbonate, and formate on TiO2. J Phys Chem B, 2002, 106(43): 11240―11245 doi: 10.1021/jp0211988
Anpo M, Aikawa N, Kubokawa Y. Photocatalytic hydrogenationof alkynes and alkenes with water over titanium dioxide. Platinumloading effect on the primary processes. J Phys Chem, 1984, 88(18): 3998―4000 doi: 10.1021/j150662a027
Inoue T, Fujishima A, Konishi S, Honda K. Photoelectrocatalytic reduction of carbon dioxide inaqueous suspensions of semiconductor powders. Nature, 1979, 277(5698): 637―638 doi: 10.1038/277637a0
Howe R F, Gratzel M. EPRstudy of hydrated anatase under UV irradiation. J Phys Chem, 1987, 91(14): 3906―3909 doi: 10.1021/j100298a035
Serpone N, Lawless D, Disdier J, Herrmann J-M. Spectroscopic, photoconductivity, and photocatalyticstudies of TiO2 colloids: naked and with thelattice doped with Cr3+, Fe3+, and V5+ cations. Langmuir, 1994, 10(3): 643―652 doi: 10.1021/la00015a010
Fujishima A, Rao T N, Tryk D A. Titanium dioxide photocatalysis. J Photochem Photobiol C: Photochem Rev, 2000, 1(1): 1―21 doi: 10.1016/S1389-5567(00)00002-2
Tseng I H, Wu J C S. Chemicalstates of metal-loaded titania in the photoreduction of CO2. Catal Today, 2004, 97(2―3): 113―119 doi: 10.1016/j.cattod.2004.03.063
Szczepankiewicz S H, Colussi A J, Hoffmann M R. Infrared spectra of photoinducedspecies on hydroxylated titania surfaces. J Phys Chem B, 2000, 104(42): 9842―9850 doi: 10.1021/jp0007890
Hadjiivanov K, Bushev V, Kantcheva M, Klissurski D. Infrared spectroscopy study of the species arising duringnitrogen dioxide adsorption on titania (anatase). Langmuir, 1994, 10(2): 464―471 doi: 10.1021/la00014a021
George B, Mclntyre P: In: Infrared Spectroscopy: Analytical Chemistry by Open Learning. John Wiley and Sons, London, 1988
Boccuzzi F, Chiorino A. FTIRStudy of carbon monoxide oxidation and scrambling at room temperatureover copper supported on ZnO and TiO2. 1. J Phys Chem, 1996, 100(9): 3617―3624 doi: 10.1021/jp950542g
RaskÛ J, KecskÈs T, Kiss J. Adsorption and reaction offormaldehyde on TiO2-supported Rh catalystsstudied by FTIR and mass spectrometry. J Catal, 2004, 226(1): 183―191 doi: 10.1016/j.jcat.2004.05.024
AraÒa J, MartÌnez Nieto J L, Herrera Melin JA, DoÒa RodrÌguez J M, Gonzlez DÌaz O, PÈrez PeÒa J, Bergasa O, Alvarez C, MÈndez J. Photocatalytic degradationof formaldehyde containing wastewater from veterinarian laboratories. Chemosphere, 2004, 55(6): 893―904
Boccuzzi F, Chiorino A, Manzoli M. FTIR study of methanol decompositionon gold catalyst for fuel cells. J PowerSources, 2003, 118(1―2): 304―310 doi: 10.1016/S0378-7753(03)00075-2
Popova G Y, Yu T V A, Chesalov A, Stoyanov E S. In situ FTIR study of the adsorption of formaldehyde, formic acid,and methyl formate at the surface of TiO2 (Anatase). Kinet Catal, 2000, 41: 805―811 doi: 10.1023/A:1026681321584
Boccuzzi F, Chiorino A, Manzoli M, Andreeva D, Tabakova T. FTIRstudy of the low-temperature water-gas shift reaction on Au/Fe2O3 and Au/TiO2 catalysts. J Catal, 1999, 188(1): 176―185 doi: 10.1006/jcat.1999.2636
AraÒa J, DoÒa-RodrÌguez J M, Cabo C G i, Gonz·lez-DÌaz O, Herrera-Melin J A, PÈrez-PeÒa J. FTIRstudy of gas-phase alcohols photocatalytic degradation with TiO2 and AC-TiO2. Appl Catal B: Environm, 2004, 53(4): 221―232
Rhodes M D, Pokrovski K A, Bell A T. The effects of zirconia morphologyon methanol synthesis from CO and H2 over Cu/ZrO2 catalysts: Part II. Transient-responseinfrared studies. J Catal, 2005, 233(1): 210―220 doi: 10.1016/j.jcat.2005.04.027
Chen M T, Lien C F, Liao L F, Lin J L. In-situ FTIR study of adsorption and photoreactions of CH2Cl2 on powdered TiO2. J Phys Chem B, 2003, 107(16): 3837―3843 doi: 10.1021/jp0220884
Wong G S, Kragten D D, Vohs J M. The oxidation of methanolto formaldehyde on TiO2 (110)-supported vanadiafilms. J Phys Chem B, 2001, 105(7): 1366―1373 doi: 10.1021/jp003691u