纳米片层状BiOBr_xI_(1-x)的制备及可见光降解甲基橙研究
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摘要
卤氧化铋由于具有特殊的层状结构和合适的禁带宽度,表现出良好的可见光催化活性和稳定性。改变卤氧化铋复合物中卤素的组成能调节禁带宽度,优化光催化性能。采用溶剂热法制备了纳米片层状BiOBr_xI_(1-x)固溶体催化剂,利用XRD、SEM和紫外-可见漫反射谱分析了BiOBr_xI_(1-x)固溶体催化剂的结构、形貌和光学特性,并以甲基橙为目标降解物,评价其可见光催化活性。结果表明:与单体卤氧化铋相比,BiOBr_xI_(1-x)固溶体催化剂提高了可见光激发率和载流子转移率,对甲基橙的降解效果更好;当Br/I比为4/6时,BiOBr_xI_(1-x)固溶体催化剂的光催化活性最高,其降解速率常数是组成为40% BiOBr+60% BiOI的机械混合催化剂的2.7倍。通过添加活性组分捕获剂研究其光催化降解机理的结果显示:BiOBr_xI_(1-x)固溶体催化剂光降解甲基橙过程中h~+直接氧化甲基橙分子起主导作用,也存在一定的·O_2~-对甲基橙的氧化作用。
Bismuth oxide halides exhibit good photocatalytic activity and stability due to their special layered structure and suitable band gap.Changing the composition in bismuth oxide halides can adjust the band gap and optimize the photocatalytic performance.By using solvothermal method,this paper prepares nanosheetlike BiOBr_xI_(1-x) solid solution catalysts,and characterizes the structure,morphology and optical properties of the prepared catalysts by XRD,SEM and UV-vis diffuse reflectance spectrum.Then the paper evaluates the photocatalytic activity of the catalysts by using methyl orange as the target of degradation,and explores the photocatalytic degradation mechanism of the catalysts by adding the trapping agents of active component.The results show that the solid solution catalyst has higher visible light excitation,carrier transfer rate and better photocatalytic activity than pure BiOBr or BiOI catalyst.When the Br/I ratio is 4/6,the photocatalytic activity is the highest,and the degradation rate constant is 2.7 times of the mechanical mixture catalyst of 40% BiOBr+60% BiOI.The direct oxidation of methyl orange by h~+ plays a dominant role,and the oxidation of methyl orange by·O_2~- exists.
Bismuth oxide halides exhibit good photocatalytic activity and stability due to their special layered structure and suitable band gap.Changing the composition in bismuth oxide halides can adjust the band gap and optimize the photocatalytic performance.By using solvothermal method,this paper prepares nanosheetlike BiOBr_xI_(1-x) solid solution catalysts,and characterizes the structure,morphology and optical properties of the prepared catalysts by XRD,SEM and UV-vis diffuse reflectance spectrum.Then the paper evaluates the photocatalytic activity of the catalysts by using methyl orange as the target of degradation,and explores the photocatalytic degradation mechanism of the catalysts by adding the trapping agents of active component.The results show that the solid solution catalyst has higher visible light excitation,carrier transfer rate and better photocatalytic activity than pure BiOBr or BiOI catalyst.When the Br/I ratio is 4/6,the photocatalytic activity is the highest,and the degradation rate constant is 2.7 times of the mechanical mixture catalyst of 40% BiOBr+60% BiOI.The direct oxidation of methyl orange by h~+ plays a dominant role,and the oxidation of methyl orange by·O_2~- exists.
引文
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[3]王喜全,马溢阳,殷月,等.MnO2催化生成O2作电子捕获剂协同TiO2催化剂的制备及研究[J].安全与环境工程,2016,23(2):45-49.
[4]安宁,马雨威,刘聚明,等.与粉煤灰耦合增强碳掺杂TiO2的可见光催化氧化能力(英文)[J].催化学报,2018,39(12):1890-1900.
[5]王喜全,李媛,孙浩.负载型钒酸铋的制备及其光催化性能研究[J].安全与环境工程,2016,23(1):59-63,69.
[6]赫荣安,曹少文,余家国.铋系光催化剂的形貌调控与表面改性研究进展[J].物理化学学报,2016,32(12):2841-2870.
[7]马占营,任鹏,高奕红,等.可见光响应型Ag/Ag3PO4复合光催化剂的制备及其光催化性能[J].化学研究与应用,2018,30(9):1545-1549.
[8]Zhang K L,Liu C M,Huang F Q,et al.Study of the electronic structure and photocatalytic activity of the BiOCl photocatalyst[J].Applied Catalysis B:Environmental,2006,68(3):125-129.
[9]Shang M,Wang W Z,Zhang L.Preparation of BiOBr lamellar structure with high photocatalytic activity by CTAB as Br source and template[J].Journal of Hazardous Materials,2009,167(1):803-809.
[10]Xiao X,Zhang W D.Facile synthesis of nanostructured BiOI microspheres with high visible light-induced photocatalytic activity[J].Journal of Materials Chemistry,2010,20(28):5866-5870.
[11]Zhang J F,Lv J L,Dai K,et al.One-step growth of nanosheet-assembled BiOCl/BiOBr microspheres for highly efficient visible photocatalytic performance[J].Applied Surface Science,2018,430:639-646.
[12]Su X D,Yang J J,Yu X,et al.In situ grown hierarchical 50% BiOCl/BiOI hollow flowerlike microspheres on reduced graphene oxide nanosheets for enhanced visible-light photocatalytic degradation of rhodamine B[J].Applied Surface Science,2018,433:502-512.
[13]Wang Q,Liu Z Q,Liu D M,et al.Ultrathin two-dimensional BiOBrxI1-x solid solution with rich oxygen vacancies for enhanced visible-light-driven photoactivity in environmental remediation[J].Applied Catalysis B:Environmental,2018,236:222-232.
[14]Jiang J,Zhao K.Synthesis and facet-dependent photoreactivity of BiOCl single crystalline nanosheets[J].Journal of the American Chemical Society,2012,134(10):4473-4476.
[15]Yin M C,Li Z S,Kou J H,et al.Mechanism investigation of visible light-induced degradation in a heterogeneous TiO2/Eosin Y/Rhodamine B system[J].Environmental Science and Technology,2009,43(21):8361-8366.
[16]Cao J,Li X,Lin H L,et al.In situpreparation of novel p-njunction photocatalyst BiOI/(BiO)2CO3 with enhanced visible light photocatalytic activity[J].Journal of Hazardous Materials,2012,239/240:316-324.
[17]Wang Y N,Deng K J,Zhang L Z.Visible light photocatalysis of BiOI and its photocatalytic activity enhancement by in situ ionic liquid modification[J].Journal of Physical Chemistry C,2011,115(29):14300-14308.