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Advances in Material Chemistry
Vol.1 No.2(2013), Article ID:12508,3 pages DOI:10.12677/AMC.2013.12004

Preparation and Photocatalytic Electrocatalytic Properties of γ-Bi2MoO6*

Huidong Xie1,2#, Wei Yang1, Zhiqi Wang1, Yahong Yao1, Yajuan Zhao1, Xiaochang Wang2

1School of Science, Xi’an University of Architecture and Technology, Xi’an

2Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi’an University of Architecture and Technology, Xi’an

Email: #xiehuidong@tsinghua.org.cn

Received: May 18th, 2013; revised: Sep. 10th, 2013; accepted: Sep. 20th, 2013

Copyright © 2013 Huidong Xie et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT:

γ-Bi2MoO6 was prepared by a mixed solvothermal method, using Bi(NO3)3·5H2O and (NH4)6Mo7O24·4H2O as raw materials. X-ray powder diffraction (XRD), infrared spectra (IR), and scanning electron microscopy (SEM) were used to characterize the as-prepared γ-Bi2MoO6. The as-prepared products showed a single phase and a microsphere structure. The photodegradation test showed that γ-Bi2MoO6 had performance degradation of methyl orange. The cyclic voltammetry demonstrated that γ-Bi2MoO6 accelerated the rate of electron transfer of K4Fe(CN)6/K3Fe(CN)6.

Keywords: Bismuth Molybdate; Preparation; Photocatalysis; Electrocatalytic

γ-Bi2MoO6微米球的制备及其光电催化性能*

谢会东1,2#,杨  薇1,王志奇1,姚亚红1,赵亚娟1,王晓昌2

1西安建筑科技大学,理学院,西安

2西安建筑科技大学,教育部西北水资源环境生态重点实验室,西安

Email: #xiehuidong@tsinghua.org.cn

摘 要:

以Bi(NO3)3·5H2O和(NH4)6Mo7O24·4H2O等为原料,采用混合溶剂热法制备了γ-Bi2MoO6。采用X-射线粉末衍射(XRD)、红外光谱(IR)和扫描电镜(SEM)等手段对制得的γ-Bi2MoO6进行了分析表征。所得产物为单相微米球状,光催化实验显示产物具有一定的降解甲基橙性能,循环伏安曲线显示产物能够促进K4Fe(CN)6/ K3Fe(CN)6电对之间的电子传递。

收稿日期:2013年5月18日;修回日期:2013年9月10日;录用日期:2013年9月20日

关键词:钼酸铋;制备;光催化;电催化

1. 引言

γ-Bi2MoO6是最简单的铋层状结构铁电化合物,主要用在催化、气敏元件和氧离子导体方面,用作催化剂时可用于催化氧化CO为CO2[1,2],催化氧化丙烯等碳氢化合物、选择性氧化和氨解氧化石蜡[3]和可见光光解水等[4]。较多的文献报道具有可见光降解有机染料的性能[5-7]。γ-Bi2MoO6制备方法主要有:固相合成法[8]、水热法[9-12]、微波水热法[2,13]、溶剂热法[14,15]、燃烧法[16]、共沉淀法[17]、熔盐法[18]和喷雾法[19]等。不同的合成方法对于产物的形貌、结构乃至性能等有较大影响,文献报道的形貌有片状[2,18]、带状[14]、空心管状[20]、花状[15]、空心球状[19,21]等。迄今为止,文献对于混合溶剂热法制备的γ-Bi2MoO6的光催化性能报道较少,尚没有文献对于γ-Bi2MoO6的电催化性能报道。本文采用乙醇和乙二醇混合溶剂热法合成了γ-Bi2MoO6,采用X-射线粉末衍射、红外光谱和扫描电镜等分析手段对制得的γ-Bi2MoO6进行了分析表征。同时考察了γ-Bi2MoO6催化剂对废水中有机染料甲基橙的降解和电催化性能。

2. 实验

2.1. γ-Bi2MoO6的制备

所有化学试剂均为分析纯。将1.2125 g (2.5 mmol) Bi(NO3)3·5H2O和0.2206 g (0.179 mmol) (NH4)6Mo7O24·4H2O加入到10 mL乙二醇溶液中,超声10 min,待其全部溶解后,加入30 mL溶有0.3 g尿素的无水乙醇溶液,搅拌均匀后,转入50 mL水热反应釜中。将反应釜密封,置于烘箱中160℃恒温反应12 h。反应完毕后,待反应釜自然冷却至室温,取出沉淀,依次用去离子水和乙醇离心洗涤直至清洗液呈中性,然后置于烘箱中60℃干燥24 h,所得样品进行分析表征和性能测试。

2.2. 性能测试和表征

产物的物相分析用型号为日本理学公司的D/Max2550VB + /PC的X射线衍射仪测定,测定条件为Cu Kα靶,管电流50 mA,管电压40 kV,扫描步长0.02˚,测定范围3˚~90˚。红外光谱分析采用日本岛津IR Prestige-21型傅立叶变换红外光谱仪。扫描电镜(日本电子公司,型号:JEOL JSM-5800,加速电压20 kV)。

光催化实验在自制的夹套式光反应器中进行,500 W氙灯光源(CEL-LAX 500,北京中教金源科技有限公司),取10 mg/L的甲基橙和0.1 g的产物,超声10 min,避光搅拌30 min,使溶液和催化剂达到吸附平衡后,打开氙灯,每隔30 min取一次样,8000 rpm离心分离,然后取上层清液,采用722型分光光度计在464 nm波长下测定甲基橙的吸光度。

电化学性质分析采用上海辰华仪器公司电化学工作站,型号:CHI660,常规三电极系统,以碳糊电极或修饰碳糊电极为工作电极,饱和甘汞电极为参比电极,铂丝电极为辅助电极,利用循环伏安法研究电对在修饰电极上的电化学行为,采用的氧化-还原电对为5 mmol·L−1 K4Fe(CN)6/K3Fe(CN)6,电解质溶液为0.1 mol·L−1 KCl。

3. 结果与讨论

3.1. X射线衍射

图1为混合溶剂法所制备的产物的XRD谱图。从图中可以看出,XRD峰形尖锐,和JCPDS卡(No. 72-1524)上正交钼铋矿相结构的γ-Bi2MoO6较一致。产物中没有其它杂质峰的存在,表明在此条件下生成了单相物质。此外,样品的峰形窄而强,说明其结晶度很好。

Figure 1. XRD pattern of γ-Bi2MoO6

图1. γ-Bi2MoO6的X射线衍图

3.2. 红外光谱分析

红外光谱常用来表征产物的化学键结构。图2显示了混合溶剂热法所制备γ-Bi2MoO6在波数为400~ 1500 cm−1范围的红外光谱。红外光谱808 cm−1处的带为共角的MoO6八面体的ν1(A)和ν3(F2)振动(Mo-O伸缩振动),518 cm−1附近的带为Mo-O-Bi振动模式。红外光谱中1385 cm−l处的峰可能是起始物的吸收峰。在459 cm−1附近处出现了吸收峰,是Bi-O键的伸缩振动吸收峰[22]

3.3. SEM形貌分析

图3是在所合成的γ-Bi2MoO6粉体的SEM照片。从图中可以看出,在该条件下所制备的粉体结晶呈致密球形,粒径变化范围较大,从数百纳米到3微米。

3.4. 光催化活性

图4为γ-Bi2MoO6对甲基橙的吸光度和光照时间的关系。如图所示,在没有加入γ-Bi2MoO6催化剂时,甲基橙溶液在氙灯照射2.5 h后,吸光度几乎没有什么变化(<1%)。这表明在没有催化剂参与的情况下,较长时间内甲基橙溶液在可见光照射下是比较稳定的。从图中还可以看到,在添加γ-Bi2MoO6光催化剂的催化体系中,随着光照时间的增加,甲基橙的吸光度逐渐降低,经过2.5 h的可见光照射后,甲基橙的吸光度降低达到29.5%。

3.5. 电催化性能

图5为γ-Bi2MoO6修饰电极和裸电极对K4Fe(CN)6/

Figure 2. Infrared spectra of γ-Bi2MoO6

图2. γ-Bi2MoO6的红外光谱图

(a)(b)

Figure 3. SEM images of γ-Bi2MoO6, scale: (a) 10 μm, (b) 5 μm

图3. γ-Bi2MoO6的SEM照片,标尺: (a) 10 μm,(b) 5 μm

Figure 4. Maximum absorbance vs time of photodegradation methyl orange using γ-Bi2MoO6

图4. γ-Bi2MoO6光降解甲基橙溶液最大吸光度与时间的关系

Figure 5. Cyclic voltammograms of the bare electrode and γ-Bi2MoO6 modified electrode

图5. γ-Bi2MoO6修饰电极和裸电极的循环伏安曲线

K3Fe(CN)6响应的循环伏安关系。如图所示,裸电极电流信号弱,且不可逆,在电位为0.573 V处有一个氧化峰,对应的峰电流值分别为55.3 μA;在−0.22 V处有一个还原峰,对应的峰电流值为49.9 μA。对比两曲线图可以发现γ-Bi2MoO6修饰电极不仅具有较高的峰电流值(氧化峰电流Ipa = 130 μA,还原峰电流Ipc = 134.9 μA),峰电位差变少(ΔEp = 0.377 V,Epa = 0.388 V,Epc = 0.011 V),说明修饰电极可逆性较好,γ-Bi2MoO6是一种良好的电极修饰材料,具有较强的促进K4Fe(CN)6/K3Fe(CN)6对电子传递的作用。

4. 结论

1) 采用混合溶剂热法制备了γ-Bi2MoO6。所得产物为单相实心微米球状结构,在可见光照射下显示一定的可见光催化活性,2.5 h对甲基橙的降解率为29.5%。

2) γ-Bi2MoO6是一种良好的电极修饰材料,氧化还原峰电流大大增强,峰电位差减小,说明γ-Bi2MoO6具有较强的促进K4Fe(CN)6/K3Fe(CN)6电对电子传递的作用。

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NOTES

*资助信息:中国博士后基金特别资助项目,编号:2012T50801。

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