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

Effect of oxidation degree of graphene oxide on photocatalytic activity of bismuth phosphate/graphene composite aerogel

三维网络结构磷酸铋/石墨烯复合气凝胶(BiPO4/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BiPO4/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BiPO4形成气凝胶,且BiPO4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BiPO4/GA复合材料难以保持气凝胶形状.高氧化程度BiPO4/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BiPO4/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BiPO4/GA气凝胶的光催化活性.光催化机理为BiPO4/GA气凝胶表面吸附富集有机污染物,光生电子从BiPO4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(·O2-)进行有机物的有效氧化降解.

Three-dimensional network bismuth phosphate/graphene aerogel(BiPO4/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 BiPO4,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 BiPO4/GA composite material with high oxidation degree was about 1.88 and 2.34 times of that with low oxidation degree BiPO4/GA,respectively.The results demonstrated that the photocatalytic activity of BiPO4/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 BiPO4/GA aerogel.The photogenic electrons were transferred from BiPO4 to the graphene layer,and effective oxidative degradation of organic compounds was carried out through the holes and superoxide radical(·O2-)generated on the catalyst.