γ射线辐照合成石墨烯/银复合多孔气凝胶及其对硝基苯酚的催化性能

Synthesis of graphene/silver aerogel composites via gamma ray irradiation and its catalytic ability for 4-nitrophenol

在乙醇/水体系及N2氛围中,利用一步伽马射线辐照法将氧化石墨烯和银离子原位还原,并组装成具有三维网络结构的石墨烯/银复合多孔水凝胶(GH/Ag),通过冷冻干燥法得到石墨烯/银复合多孔气凝胶(GA/Ag)。通过场发射扫描电子显微镜观察到GA/Ag具有类蜂窝状的多孔网络结构;通过高分辨-透射电子显微镜可以观察到银纳米粒子尺寸范围在20~60 nm;并通过X射线光电子能谱、X射线衍射仪和热重分析等方法表明石墨烯/银纳米粒子复合材料中C元素含量增加,O元素含量降低,同时Ag+被还原及热稳定性增加。由于石墨烯和银纳米粒子之间的协同催化效应,GA/Ag对4-硝基苯酚表现出优异的催化性能,催化浓度高达2.16×10^?3 mol/L。当4-硝基苯酚浓度为0.72×10^?3 mol/L时,该催化反应一级动力学常数为1.53 min^?1,远高于常规化学法制备的复合材料的催化性能。

In an ethanol/water system and N2 atmosphere,graphene oxide and the silver ions were simultaneously reduced by a one-step gamma ray irradiation method and self-assembled into graphene/silver(GH/Ag)composite porous hydrogel materials with a three-dimensional structure.GA/Ag composite porous aerogels were obtained by the freeze-drying method.Scanning electron microscopy observed that GA/Ag composites have a honeycomb-like network structure.Transmission electron microscopy analysis revealed that silver nanoparticles have a size range of 20~60 nm.The results of X-ray photoelectron spectroscopy,X-ray diffraction and thermogravimetric analysis showed that the C element content in the GA/Ag composites increased,the O element content decreased,and Ag+was reduced and thermal stability increased.Due to the synergistic catalysis between graphene and Ag nanoparticles,GA/Ag composites demonstrated excellent catalytic performance and catalyzed the concentration of 4-nitrophenol up to 2.16×10^?3 mol/L.When the concentration of 4-nitrophenol was 0.72×10^?3 mol/L,the first-order kinetic constant k was 1.53 min^?1,which was higher than those synthesized by chemical methods.