Fe掺杂对改善g-C_3N_4结构提升光催化活性的影响
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摘要
石墨相氮化碳已经成为光催化领域、特别是光催化材料领域的研究热点。本文以尿素为原料,引入少量的硝酸铁改性,制备了不同含量的Fe掺杂的g-C_3N_4催化剂。采用SEM、XRD、IR、XPS、UV-Vis、PL等手段对催化剂样品表征。结果表明,Fe的掺杂有利于g-C_3N_4的剥离,影响了g-C_3N_4的能带结构,增强了其对可见光的吸收,提高电子-空穴对的分离效率。并以罗丹明B水溶液模拟废水,在可见光下考察催化剂的光催化降解性能,发现当Fe掺杂量为0. 3%时效果最佳,降解速率是g-C_3N_4的1. 62倍,且研究发现超氧自由基与空穴是该体系下的主要活性物种。
Graphite carbon nitride has become the hot research material in the field of photocatalysis and photocatalytic materials. In this study, a series of Fe-doped graphitic carbon nitride( g-C_3N_4)photocatalysts were prepared using urea and ferric nitrate as precursors. The resulting Fe/g-C_3N_4 composite photocatalysts were characterized by scanning electron microscope( SEM),X-ray diffraction( XRD), infrared spectrum( IR), X-ray photoelectron spectroscopy( XPS), ultraviolet-visible spectroscopy( UV-Vis) and photoluminescence spectroscopy( PL). Results indicate that Fe doping could promote the exfoliation and change the optical properties of g-C_3N_4,affected the energy band structure,enhanced the absorption of visible light,and improved the electron-hole separation rate. The photocatalytic degradation of rhodamine B solution was performed under visible light irradiation. The photocatalytic activity of Fe-doped g-C_3N_4 sample is highest when 0. 3% Fe is loaded on the substrate,the rate constant for the photocatalyst was 1. 62 times as high as that of pure g-C_3N_4. It was also found that the superoxide radical and hole were the main active species for catalytic degradation in this system.
Graphite carbon nitride has become the hot research material in the field of photocatalysis and photocatalytic materials. In this study, a series of Fe-doped graphitic carbon nitride( g-C_3N_4)photocatalysts were prepared using urea and ferric nitrate as precursors. The resulting Fe/g-C_3N_4 composite photocatalysts were characterized by scanning electron microscope( SEM),X-ray diffraction( XRD), infrared spectrum( IR), X-ray photoelectron spectroscopy( XPS), ultraviolet-visible spectroscopy( UV-Vis) and photoluminescence spectroscopy( PL). Results indicate that Fe doping could promote the exfoliation and change the optical properties of g-C_3N_4,affected the energy band structure,enhanced the absorption of visible light,and improved the electron-hole separation rate. The photocatalytic degradation of rhodamine B solution was performed under visible light irradiation. The photocatalytic activity of Fe-doped g-C_3N_4 sample is highest when 0. 3% Fe is loaded on the substrate,the rate constant for the photocatalyst was 1. 62 times as high as that of pure g-C_3N_4. It was also found that the superoxide radical and hole were the main active species for catalytic degradation in this system.
引文
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[2]Zhang J,Zhang M,Yang C,et al.Nanospherical Carbon Nitride Frameworks with Sharp Edges Accelerating Charge Collection and Separation at a Soft Photocatalytic Interface[J].Advanced Materials,2014,26(24):4121-4126.
[3]Chen K,Chai Z,Li C,et al.Catalyst-Free Growth of Three-Dimensional Graphene Flakes and Graphene/g-C3N4Composite for Hydrocarbon Oxidation[J].ACS Nano,2016,10(3):3665-3673.
[4]Wang X C,Maeda K,Thomas A,et al.A metal-free polymeric photocatalyst for hydrogen production from water under visible light[J].Nature Materials,2009,8:76-80.
[5]Zhang J S,Zhang M W,Yang C,et al.Nanospherical Carbon Nitride Frameworks with Sharp Edges Accelerating Charge Collection and Separation at a Soft Photocatalytic Interface[J].Advanced Materials,2014,26(24):4121-4126.
[6]Shi L,Wang T,Zhang H B,et al.Electrostatic Self-Assembly of Nanosized Carbon Nitride Nanosheet onto a Zirconium Metal-Organic Framework for Enhanced Photocatalytic CO2Reduction[J].Advanced Functional Materials,2015,25(33):5360-5367.
[7]Huang Q,Yu J G,Cao S W,et al.Efficient photocatalytic reduction of CO2by amine-functionalized g-C3N4[J].Applied Surface Science,2015,358:350-355.
[8]Wang M Q,Yang W H,Wang H H,et al.Pyrolyzed Fe-N-C Composite as an Efficient Non-precious Metal Catalyst for Oxygen Reduction Reaction in Acidic Medium[J].ACS Catalysis,2014,4(11):3928-3936.
[9]Lang X J,Chen X D,Zhao J C.Heterogeneous visible light photocatalysis for selective organic transformations[J].Chemical Society Reviews,2014,43:473-486.
[10]Xiao J D,Xie Y B,Nawaz F,et al.Dramatic coupling of visible light with ozone on honeycomb-like porous g-C3N4towards superior oxidation of water pollutants[J].Applied Catalysis B:Environmental,2016,183:417-425.
[11]Shen T T,Lang D,Cheng F Y,et al.Ternary Reduced Graphene Oxide/g-C3N4/Ag-AgCl Nanocomposites for Controlled Visible-Light Photocatalytic Selectivity[J].ChemistrySelect,2016,1(5):1006-1015.
[12]Meng Q G,Yuan M Z,Lv H Q,et al.Facile Construction of Metal-Free g-C3N4Isotype Heterojunction with Highly Enhanced Visibl-light Photocatalytic Performance[J].ChemistrySelect,2017,2(24):6970-6978.
[13]Zhang J,Zhang M,Yang C,et al.Nanospherical Carbon Nitride Frameworks with Sharp Edges Accelerating Charge Collection and Separation at a Soft Photocatalytic Interface[J].Advanced Materials,2014,26(24):4121-4126.
[14]阮林伟,裘灵光,朱玉俊,等.g-C3N4碳位掺杂电学及光学性质的分析[J].物理化学学报,2014,30(1):43-52.
[15]Ong W J,Tan L L,Ng Y H,et al.Graphitic Carbon Nitride(g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation:Are We a Step Closer To Achieving Sustainability?[J].Chemical Reviews,2016,116(12):7159-7329.
[16]Han Q,Bing W,Jian G,et al.Atomically Thin Mesoporous Nanomesh of Graphitic C3N4for High-Efficiency Photocatalytic Hydrogen Evolution[J].ACS Nano,2016,10(2):2745-2751.
[17]Erwin S C,Zu L,Haftel M I,Efros A L,Kennedy T A,Norris D J.Doping semiconductor nanocrystals[J].Nature,2005,436:91-94.
[18]Wang X C,Chen X F,Thomas A,et al.Antonietti M,Metal-Containing Carbon Nitride Compounds:A New Functional Organic-Metal Hybrid Material[J].Advanced Materials,2009,21:1609-1612.
[19]Liu Q,Guo Y R,Chen Z H,et al.Constructing a novel ternary Fe(III)/graphene/g-C3N4compositephotocatalyst with enhanced visible-light driven photocatalyticactivity via interfacial charge transfer effect[J].Applied Catalysis B:Environmental,2016,183:231-241.
[20]Gao J T,Wang Y,Zhou S J,et al.A Facile One-Step Synthesis of Fe-Doped g-C3N4Nanosheets and Their Improved Visible-Light Photocatalytic Performance[J].ChemCatChem,2017,9:1708-1715.
[21]刘翀,刘丽来,聂佳慧.高活性碳球修饰g-C3N4的制备及光催化性能[J].高等学校化学学报,2018,39(7):1511-1517.
[22]张华森,李喜宝,冯志军,等.加热温度对尿素水溶液制备类石墨相氮化碳的影响及其机理[J].硅酸盐学报,2018,46(2):281-287.
[23]Guo Y,Li J,Yuan Y,et al.A Rapid Microwave-Assisted Thermolysis Route to Highly Crystalline Carbon Nitrides for Efficient Hydrogen Generation[J].Angewandte Chemie International Edition,2016,55(47):14693-14697.
[24]Gao J,Wang Y,Zhou S,et al.A Facile One Step Synthesis of Fe Doped g-C3N4Nanosheets and Their Improved Visible-Light Photocatalytic Performance[J].Chem.Cat.Chem.,2017,9(9):1708-1715.
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[30]Zhang Y L,Ma L L,Wang T J,et al.MnO2coated Fe2O3spindles designed for production of C5+hydrocarbons in Fischer-Tropsch synthesis[J].Fuel,2016,177:197-205.
[31]Shen T T,Lang D,Cheng F Y,et al.Ternary Reduced Graphene Oxide/g-C3N4/Ag-AgCl Nanocomposites for Controlled Visible Light Photocatalytic Selectivity[J].Chemistry Select,2016,1(5):1006-1015.
[32]Meng Q G,Yuan M Z,Lv H Q,et al.Facile Construction of Metal Free g-C3N4Isotype Heterojunction with Highly Enhanced Visible light Photocatalytic Performance[J].Chemistry Select,201,2(24):6970-6978.
[33]Liu J,Yang H M,Liu N Y,et al.Total photocatalysis conversion from cyclohexane to cyclohexanone by C3N4/Au nanocomposites[J].Green Chemistry,2014,16(10):4559-4565.