Keggin型铬取代的磷钨杂多阴离子/二氧化钛纳米膜光催化剂的制备及可见光催化性能

doi:10.11944/j.issn.1000-0518.2016.03.150258

摘要/Abstract

摘要：

以钛酸四丁酯Ti(OC₄H₉)₄为TiO₂前驱体,Keggin型铬取代的杂多阴离子PW₁₁Cr为可见光活性组分,采用溶胶-凝胶提拉法在玻片表面制备了PW₁₁Cr/TiO₂纳米膜光催化剂,并用UV-Vis DRS、IR、XRD、SEM和TEM等技术手段对催化剂的光吸收性质、化学组成、晶相和表面结构形貌等进行了表征;讨论了膜中PW₁₁Cr和TiO₂相互作用的方式;以染料模型污染物RhB的可见光催化降解为探针,评估了PW₁₁Cr/TiO₂光催化剂的可见光催化活性,讨论了光催化反应机理,并与TiO₂的光催化反应机理进行了比较;考察了焙烧温度、PW₁₁Cr剂量和溶液pH值对光催化活性的影响;最后用RhB的循环降解实验评估了催化剂的光催化稳定性。实验结果表明,PW₁₁Cr/TiO₂光催化剂对可见光有明显吸收,较低焙烧温度(100 ℃)下得到的膜为无定形结构,而较高焙烧温度(500 ℃)为纳晶结构;前者的光催化活性较高,在200 W金卤灯照射下降解10 μmol/L RhB,120 min的降解率为95%,4 h的COD去除率为72%;羟基自由基是导致RhB降解的主要氧活性物质;低的膜处理温度,高的PW₁₁Cr负载量和溶液酸性有利于提高PW₁₁Cr/TiO₂膜的光催化活性;经循环重复使用10次,PW₁₁Cr/TiO₂膜的光催化活性仅有较少损失。

关键词: Keggin型铬取代磷钨杂多阴离子, 二氧化钛, 可见光催化剂, 溶胶-凝胶法, 罗丹明B

Abstract:

A PW₁₁Cr/TiO₂ nano film photocatalyst was prepared on the surface of a glass slide via the sol-gel dipping pulling method using tetrabutyl titanate Ti(OC₄H₉)₄ as the precursor of TiO₂ and the Keggin type chromium substituted heteropolyanion(PW₁₁Cr) as the visible light active component. Then the light absorption properties, chemical composition, crystal phase and surface morphology of the as-prepared catalyst were characterized using solid ultraviolet-visible diffuse reflection spectroscopy, infrared spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The interaction between PW₁₁Cr and TiO₂ in the film was discussed. Visible photocatalytic activity of the catalyst was assessed using photocatalytic degradation of RhB as a probe. Meanwhile, a photocatalysis mechanism was suggested and compared with that of TiO₂. Influences of the calcination temperature, the PW₁₁Cr dosage and the solution pH on the catalyst activity were also examined. In the end, a recycle test of the catalyst for RhB degradation was employed to evaluate the stability of the catalyst. The PW₁₁Cr/TiO₂ photocatalyst has a good absorption of visible light. The film obtained at low calcination temperature(100 ℃) is amorphous but crystal at high calcination temperature(500 ℃). The former has higher photocatalytic activity, and is employed to degrade RhB with a concentration of 10 μmol/L under the irradiation of 200 W metal halide lamp. The degradation ratio is 95% at 120 min and the COD removal is 72% at 4 h. The hydroxyl radicals are the main reactive oxygen species leading to RhB degradation. Low processing temperature, high PW₁₁Cr dosage and high solution acidity are favorable to enhance the photocatalytic activity of the PW₁₁Cr/TiO₂ film. After recycles of 10 times for RhB degradaion, the photocatalytic activity of the PW₁₁Cr/TiO₂ film lose insignificantly.

Key words: Keggin-type Cr-substituted phosphotungstates, titanium dioxide, visible photocatalyst, sol-gel method, rhodamine B

邹晓梅, 陈艳, 朱兴旺, 刘高鹏, 郭心玮, 雷琴, 柯小雪, 李帅星, 华英杰, 王崇太. Keggin型铬取代的磷钨杂多阴离子/二氧化钛纳米膜光催化剂的制备及可见光催化性能[J]. 应用化学, 2016, 33(3): 320-329.

ZOU Xiaomei, CHEN Yan, ZHU Xingwang, LIU Gaopeng, GUO Xinwei, LEI Qin, KE Xiaoxue, LI Shuaixing, HUA Yingjie, WANG Chongtai. Preparation of the Keggin Type Chromium Substituted Phosphotungstates/Titanium Dioxide Nano Film and Its Visible Photocatalytic Performance[J]. Chinese Journal of Applied Chemistry, 2016, 33(3): 320-329.

参考文献

[1]	Honda K,Fujishima A. Electrochemical Photolysis of Water at a Semiconductor Electrode[J]. Nature,1972,238(5358):37-38.
[2]	Fujishima A,Rao T N,Tryk D A. Titanium Dioxide Photocatalysis[J]. J Photochem Photobiol C,2000,1(1):1-21.
[3]	Chen X B,Mao S S. Titanium Dioxide Nanomaterials:Synthesis, Properties, Modifications, and Applications[J]. Chem Rev,2007,107(7):2891-2959.
[4]	Kamat P V. TiO2 Nanostructures:Recent Physical Chemistry Advances[J]. J Phy Chem C,2012,116(22):11849-11851.
[5]	Pelaez M,Nolan N T,Pillai S C,et al.A Review on the Visible Light Active Titanium Dioxide Photocatalysts for Environmental Applications[J]. Appl Catal B:Environ,2012,125(33):331-349.
[6]	Nakata K,Ochiai T,Murakami T,et al.Photoenergy Conversion with TiO2 Photocatalysis:New Materials and Recent Applications[J]. Electrochim Acta,2012,84(12):103-111.
[7]	Nakata K,Fujishima A. TiO2 Photocatalysis:Design and Applications[J]. J Photochem Photobiol C:Photochem Rev,2012,13(3):169-189.
[8]	Zhang R Y,Elzatahry A A, Al-Deyab S S, et al. Mesoporous Titania:from Synthesis to Application[J]. Nano Today,2012,7(4):344-366.
[9]	Daghrir R,Drogui P,Robert D. Photoelectrocatalytic Technologies for Environmental Applications[J]. J Photochem Photobiol A:Chem,2012,238(238):41-52.
[10]	Djaoued Y,Badilescu S,Ashrit P V. Low Temperature Sol-Gel Preparation of Nanocrystalline TiO2 Thin Films[J]. J Sol-Gel Sci Technol,2002,24(3):247.
[11]	Shi J W,Yan X,Cui H J,et al.Low-Temperature Synthesis of CdS/TiO2 Composite Photocatalysts:Influence of Synthetic Procedure on Photocatalytic Activity under Visible Light[J]. J Mol Catal A:Chem,2012,356:53-60.
[12]	WANG Enjun,YANG Huiyun,CAO Yaan. Photocatalytic Activity of Visible-Light-Driven Zirconium Doped TiO2 Photocatalysts[J]. Acta Chim Sinica,2009,67(24):2759-2764(in Chinese). 王恩君,杨辉云,曹亚安. Zr离子掺杂TiO2可见光催化剂光催化活性的研究[J]. 化学学报,2009,67(24):2759-2764.
[13]	Zhang Y X,Zhou Z Y,Chen T,et al.Graphene TiO2 Nanocomposites with High Photocatalytic Activity for the Degradation of Sodium Pentachlorophenol[J]. J Environ Sci,2014,26(10):2114-2122.
[14]	Wang Y,He Y M,Lai Q H,et al.Review of the Progress in Preparing Nano TiO2:An Important Environmental Engineering Material[J]. J Environ Sci,2014,26(11):2139-2137.
[15]	Spanhel L,Weller H,Henglein A. Photochemistry of Semiconductor of Colloids[J]. J Am Chem Soc,1987,109(22):6632-6635.
[16]	WANG Chongtai,SUN Zhenfan,HUA Yingjie,et al.Photocatalytic Degradation of Nitrobenzene with Keggin-typeFe(Ⅲ)-Substituted Heteropolyanion PW11O39Fe(Ⅲ)(H2O)4-[J]. Acta Chim Sin,2010,68(11):1037-1042(in Chinese). 王崇太,孙振范,华英杰,等. Keggin型铁取代杂多阴离子PW11O39Fe(Ⅲ)(H2O)4-光催化降解硝基苯[J]. 化学学报,2010,68(11):1037-1042.
[17]	HUA Yingjie,WANG Chongtai,SUN Zhenfan,et al.Photocatalytic Degradation of Aniline by a Novel Photo-Fenton-Like System Consisting of PW11O39Fe(Ⅲ)(H2O)4-/H2O2[J]. Chinese J Appl Chem,2012,29(1):63-68(in Chinese). 华英杰,王崇太,孙振范,等. 新颖的PW11O39Fe(Ⅲ)(H2O)4-/H2O2类光-芬顿体系光催化降解苯胺[J]. 应用化学,2012,29(1):63-68.
[18]	WANG Chongtai,HUA Yingjie,LIU Xilong,et al.Visible Photocatalytic Degradation of Rhodamine B Using Keggin Type Cr(Ⅲ)-Substituted Heteropolyanion PW11O39Cr(Ⅲ)(H2O)4-[J]. Acta Chim Sin,2012,70(4):399-404(in Chinese). 王崇太,华英杰,刘希龙,等. 铬取代杂多阴离子PW11O39Cr(Ⅲ)(H2O)4-可见光催化降解罗丹明B[J]. 化学学报,2012,70(4):399-404.
[19]	WU Chunyan,LIU Xilong,SHEN Guoying,et al.Visible Photocatalytic Degradation of Rhodamine B Using Copper-Substituted Tungstophosphate Heteropolyanion[J]. Chinese J Appl Chem,2012,29(9):1030-1035(in Chinese). 吴春燕,刘希龙,沈国英,等. Keggin型铜取代磷钨杂多阴离子可见光催化降解罗丹明B[J]. 应用化学,2012,29(9):1030-1035.
[20]	Hua Y J,Wang C T,Liu J Y,et al.Visible Photocatalytic Degradation of Rhodamine B Using Fe(Ⅲ)-Substituted Phosphotungstic Heteropolyanion[J]. J Mol Catal A:Chem,2012,365:8-14.
[21]	Hua Y J,Chen G L,Xu X N,et al.Comparative Study of Homogeneous and Heterogeneous Photocatalytic Degradation of RhB under Visible Light Irradiation with Keggin-Type Manganese-Substituted Catalysts[J]. J Phys Chem C,2014,118(17):8877-8884.
[22]	HUA Yingjie,XU Xiaonan,ZOU Xiaomei,et al.A Study on the Visible Photocatalytic Property of PW11O39Co(Ⅱ)(H2O)5- in Homogeneous and Heterogeneous Systems[J]. Chinese J Inorg Chem,2014,30(8):1895-1903(in Chinese). 华英杰,徐孝南,邹晓梅,等. PW11O39Co(Ⅱ)(H2O)5-的均相及异相体系可见光催化性能研究[J]. 无机化学学报,2014,30(8):1895-1903.
[23]	Toth J E,Anson F C. Electrochemical Properties of Iron(Ⅲ)-Substituted Heteropolytungstate Anions[J]. J Electroanal Chem,1988,256(2):361-370.
[24]	Rong C Y,Pope M T. Lacunary Polyoxometalate Anions Are Π-Acceptor Ligands. Characterization of Some Tungstoruthenate(Ⅱ,Ⅲ,Ⅳ,Ⅴ) Heteropolyanions and Their Atom-Transfer Reactivity[J]. J Am Chem Soc,1992,114(8):2932-2938.
[25]	Toth J E,Anson F C. Electrocatalytic Reduction of Nitrite and Nitric Oxide to Ammonia with Iron-Substituted Polyoxotungstates[J]. J Am Chem Soc,1989,111(7):2444-2451.
[26]	Troupis A,Triantis T M,Gkika E,et al.Photocatalytic Reductive-Oxidative Degradation of Acid Orange 7 by Polyoxometalates[J]. Appl Catal B,2009,86(s1/2):98-107.
[27]	Yang Y,Guo YH,Hu CW,et al.Lacunary Keggin-Type Polyoxometalates-Based Macroporous Composite Films:Preparation and Photocatalytic Activity[J]. Appl Catal A,2003,252(2):305-314.
[28]	Chen C C,Zhao W,Lei P X,et al.Photosensitized Degradation of Dyes in Polyoxometalate Solutions Versus TiO2 Dispersions under Visible-Light Irradiation:Mechanistic Implications[J]. Chem Eur J,2004,10(8):1956-1965.
[29]	Androulaki E,Hiskia A,Dimotikali D,et al.Light Induced Elimination of Mono- and Polychlorinated Phenols from Aqueous Solutions by PW12O403-. The Case of 2,4,6-Trichlorophenol[J]. Environ Sci Technol,2000,34(10):2024-2028.
[30]	Lei P X,Chen C C,Yang J,et al.Degradation of Dye Pollutants by Immobilized Polyoxometalate with H2O2 under Visible-Light Irradiation[J]. Environ Sci Technol,2005,39(21):8466-8474.
[31]	Liu X,Li Y X,Peng S Q,et al.Photosensitization of SiW11O398--Modified TiO2 by Eosin Y for Stable Visible-Light H2 Generatio[J]. Int J Hydrogen Energy,2013,38(27):11709-11719.
[32]	Liu X,Li Y X,Peng S Q,et al.Photocatalytic Hydrogen Evolution under Visible Light Irradiation by the Polyoxometalate α-[AlSiW11(H2O)39]5--Eosin Y System[J]. Int J Hydrogen Energy,2012,37(37):12150-12157.
[33]	WANG Chongtai. Studies on Fabrications of the Cr(Ⅲ) and Fe(Ⅲ) Substituted Heteropolytungstates and Their Properties of Indirect Electrocatalytic Oxidation[D]. Guangzhou:Sun Yat-Sen University,2008(in Chinese). 王崇太. 过渡金属Cr(Ⅲ)和Fe(Ⅲ)取代磷钨杂多配合物的制备及电催化氧化性能研究[D]. 广州:中山大学,2008.
[34]	DENG Xiaoyan,CUI Zuolin,DU Fanglin,et al.Thermal Analysis Characterization of Nanosized TiO2[J]. J Inorg Mater,2001,16(6):1089-1093(in Chinese). 邓晓燕,崔作林,杜芳林,等. 纳米二氧化钛的热分析表征[J]. 无机材料学报,2001,16(6):1089-1093.
[35]	Kumar M P,Badrinarayanan S,Sastry M. Nanocrystalline TiO2 Studies by Optical, FTIR and X-ray Photoelectron Spectroscopy:Correlation to Presence of Surface States[J]. Thin Solid Films,2000,358(1/2):122-130.
[36]	Castaeda L,Alonso J C,Ortiz A. Spray Pyrolysis Deposition and Characterization of Titanium Oxide Thin Films[J]. Mater Chem Phys,2003,77(3):938-944.