氧化石墨烯氧化程度对磷酸铋/石墨烯复合气凝胶光催化活性的影响
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摘要
三维网络结构磷酸铋/石墨烯复合气凝胶(BiPO_4/GA)可用于有机污染物的吸附富集和原位光催化协同净化.本文采用SEM、FTIR、XRD和紫外-可见漫反射光谱(UV-Vis DRS)系统表征了氧化石墨烯(GO)及其氧化程度对BiPO_4/GA复合材料的形貌、结构、光吸收和光催化性能的影响.氧化程度较高的GO呈棕色,易与BiPO_4形成气凝胶,且BiPO_4纳米棒均匀分散在石墨烯层上.而氧化程度较低的GO颜色较深,合成的BiPO_4/GA复合材料难以保持气凝胶形状.高氧化程度BiPO_4/GA复合材料对苯酚和亚甲基蓝(MB)的降解率分别约为低氧化程度BiPO_4/GA的1.88倍和2.34倍.研究结果表明,通过提高复合材料制备原料GO的氧化程度,可以显著提高BiPO_4/GA气凝胶的光催化活性.光催化机理为BiPO_4/GA气凝胶表面吸附富集有机污染物,光生电子从BiPO_4转移到石墨烯层,并通过催化剂上产生的空穴及超氧自由基(·O_2~-)进行有机物的有效氧化降解.
Three-dimensional network bismuth phosphate/graphene aerogel(BiPO_4/GA) could be used to achieve adsorption enrichment and in situ photocatalytic synergistic purification. The effects of graphene oxide on the morphology, structure, optical absorption and photocatalytic properties of the composites were investigated using SEM, FTIR, XRD and DRS characterizations. The graphene oxide with higher oxidation degree turned to brown and could easily form aerogel with BiPO_4, while the color of graphene oxide with lower oxidation degree was dark and could hardly keep an aerogel shape. The degradation rate of phenol and methylene blue(MB) by BiPO_4/GA composite material with high oxidation degree was about 1.88 and 2.34 times of that with low oxidation degree BiPO_4/GA, respectively. The results demonstrated that the photocatalytic activity of BiPO_4/GA aerogel could greatly be enhanced by increasing the oxidation degree of graphene oxide. The photocatalytic mechanism was due to the adsorption of organic pollutants on the surface of BiPO_4/GA aerogel. The photogenic electrons were transferred from BiPO_4 to the graphene layer, and effective oxidative degradation of organic compounds was carried out through the holes and superoxide radical(·O_2~-) generated on the catalyst.
Three-dimensional network bismuth phosphate/graphene aerogel(BiPO_4/GA) could be used to achieve adsorption enrichment and in situ photocatalytic synergistic purification. The effects of graphene oxide on the morphology, structure, optical absorption and photocatalytic properties of the composites were investigated using SEM, FTIR, XRD and DRS characterizations. The graphene oxide with higher oxidation degree turned to brown and could easily form aerogel with BiPO_4, while the color of graphene oxide with lower oxidation degree was dark and could hardly keep an aerogel shape. The degradation rate of phenol and methylene blue(MB) by BiPO_4/GA composite material with high oxidation degree was about 1.88 and 2.34 times of that with low oxidation degree BiPO_4/GA, respectively. The results demonstrated that the photocatalytic activity of BiPO_4/GA aerogel could greatly be enhanced by increasing the oxidation degree of graphene oxide. The photocatalytic mechanism was due to the adsorption of organic pollutants on the surface of BiPO_4/GA aerogel. The photogenic electrons were transferred from BiPO_4 to the graphene layer, and effective oxidative degradation of organic compounds was carried out through the holes and superoxide radical(·O_2~-) generated on the catalyst.
引文
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[3] YANG Y,LIU F C,KAWAZOE Y,et al.Adsorption of water on fluorinated graphene [J].Journal of Physics and Chemistry of Solids,2019,124:54-59.
[4] LI J D,FANG W,YU C L,et al.Ag-based semiconductor photocatalysts in environmental purification [J].Applied Surface Science,2015,358:46-56.
[5] LIU H T,GUO Y K,WANG N N,et al.Controllable synthesis and photocatalytic activity of ultrathin hematite nanosheets [J].Journal of Alloys and Compounds,2019,771:343-349.
[6] YU X,SHI J J,FENG L J,et al.A three-dimensional BiOBr/RGO heterostructural aerogel with enhanced and selective photocatalytic properties under visible light [J].Applied Surface Science,2017,396:1775-1782.
[7] LV H,LIU Y.M,TANG H B,et al.Synergetic effect of MoS2 and graphene as cocatalysts for enhanced photocatalytic activity of BiPO4 nanoparticles [J].Applied Surface Science,2017,425:100-106.
[8] PAN C S,ZHU Y F,et al.New type of BiPO4 oxy-acid salt photocatalyst with high photocatalytic activity on degradation of dye [J].Environmental Science & Technology,2010,44:5570-5574.
[9] LI G F,DING Y,ZHANG Y F.et al.Microwave synthesis of BiPO4 nanostructures and their morphology-dependent photocatalytic performances [J].Journal of Colloid and Interface Science,2011,363:497-503.
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[12] CHEN F Y,AN W J,YAO L,et al.Fabricating 3D porous PANI/TiO2-graphene hydrogel for the enhanced UV-light photocatalytic degradation of BPA [J].Applied Surface Science,2018,427:123-132.
[13] ZHU H J,LI Z K,YANG J H,et al.A novel composite hydrogel for adsorption and photocatalytic degradation of bisphenol A by visible light irradiation [J].Chemical Engineering Journal,2018,334:1679-1690.
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[15] LIU X,WANG J,DONG Y M,et al.One-step synthesis of Bi2MoO6/reduced graphene oxide aerogel composite with enhanced adsorption and photocatalytic degradation performance for methylene blue [J].Materials Science in Semiconductor Processing,2018,88:214-223.
[16] HE Y R,LI S C,LI X L,et al.Graphene (rGO) hydrogel:A promising material for facile removal of uranium from aqueous solution [J].Chemical Engineering Journal,2018,338:333-340.
[17] WU Z S,WINTER A,Chen L,et al.Three-dimensional nitrogen and boron co-doped graphene for high-performance all-solid-state supercapacitors [J].Advanced Materials,2012,24:5130-5135.
[18] XU Y,SHENG K,LI C,et al.Self-assembled graphene hydrogel via a one-step hydrothermalprocess [J].Acs Nano,2010,4:4324-4330.
[19] YANG J J,CHEN D M,ZHU Y,et al.3D-3D porous Bi2WO6/graphene hydrogel composite with excellent synergistic effect of adsorption-enrichment and photocatalytic degradation [J].Applied Catalysis B:Environmental,2017,205:228-237.
[20] HUMMERS Jr.W S,OFFEMAN R E.Preparation of Graphitic Oxide [J].Journal of the American Chemical Society,1958,80:1339-1339.
[21] PAN L P,LIU S L,ODERINDE O,et al.Facile fabrication of graphene-based aerogel with rare earth metal oxide for water purification [J].Applied Surface Science,2018,427:779-786.
[22] MA Y H,WANG J J,XUN S M,et al.Ag2O/sodium alginate-reduced graphene oxide aerogel beads for efficient visible light driven photocatalysis [J].Applied Surface Science,2018,430:156-164.
[23] BANDA H,ARADILLA D,BENAYAD A,et al.One-step synthesis of highly reduced graphene hydrogels for high power supercapacitor applications [J].Journal of Power Sources,2017,360:538-547.
[24] JI F,LI J,CUI X L,et al.Hierarchical C-doped BiPO4/ZnCoAl-LDO hybrid with enhanced photocatalytic activity for organic pollutants degradation [J].Applied Clay Science,2018,162:182-191.
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