不同还原方法制备石墨烯及其电化学性能

Synthesis of graphene by different reduction methods and its electrochemical performance

采用Hummers改进法制备氧化石墨烯,分别选取水合肼、硼氢化钠、铝粉对所制备氧化石墨烯进行还原处理,用红外光谱(FTIR)、X射线衍射仪(XRD)、射电子显微镜(TEM)、原子力显微镜(AFM)、X射线电子能谱(XPS)对样品进行了结构、谱学、形貌表征,用高性能电池检测系统和电化学工作站对样品进行充放电测试、循环测试、CV测试和EIS测试分析。结果表明,所制备的氧化石墨烯分布相对均一、团聚现象较弱、片层厚度为1.107 nm、片层层数约为1~2层,C/O比为1.6。经过三种还原方法处理的石墨烯的含氧官能团在氧化石墨烯基础上都出现明显下降,C/O质量比分别提高到6.4、5.3、3.7。对三种不同还原方法制备的石墨烯(rGO/N_2H_4·H_2O、rGO/NaBH_4、rGO/AlP)进行电化学性能研究,导电性呈现rGO/N_2H_4·H_2O>rGO/Na BH_4>rGO/AlP趋势。导电性高,所制得的电池反应活性较高、极化较低,进而表现出较好的倍率和循环性能,GO/N_2H_4·H_2O、rGO/NaBH_4和rGO/AlP的0.2 C放电比容量分别为158.4、153.3和144.8 mAh/g;其中rGO/N_2H_4·H_2O的导电性最高,表现出更好的倍率性能和循环性能,1 C倍率保持95.5%、2 C倍率保持仍能达到90.1%,0.2 C@RT 800次循环后,容量保持率仍能达到95.3%,而rGO/NaBH_4、rGO/AlP分别为91.1%和89.6%,相对较低。

Graphene was prepared by reducing the graphene oxide in the aqueous colloidal suspension using hydrazine hydrate,sodium borohydride and aluminum powder,respectively.The samples were characterized by using infrared spectroscopy(FTIR),X-ray diffraction(XRD),transmission electron microscope(TEM),and atomic force microscope(AFM).Besides,the high performance battery detection system and electrochemical workstation methods were used to test their electrochemical properties,including charge-discharge test,cycle test,CV and EIS test.The results suggest that the obtained graphene oxide has a well distribution and nearly has no trend to aggregate,with the thickness of 1.107 nm,1-2 layers and the 1.6 C/O ratio.The oxygen containing functional groups of the graphene obtained by three reduction methods shows a significant decrease on the basis of graphene oxide,and the C/O ratio increases to 6.4,5.3,3.7,respectively.The electrochemical properties of graphene prepared by three reduction methods were compared.The results show that the graphene prepared by rGO/N2H4·H2O has the highest conductivity followed by rGO/NaBH4,and rGO/AlP has the lowest conductivity.The higher the electrical conductivity,the higher the reaction activity as well as the lower the polarization of the prepared battery.The prepared battery shows a better rate and cycle performance.When charged-discharged at 0.2,the capacity of GO/N2H4·H2O,rGO/NaBH4 and rGO/AlP are 158.4,153.3,and 144.8 mAh/g,respectively.The rGO/N2H4·H2O has the highest conductivity,shows the best rate capability and cyclic performance,and the discharge specific capacity of GO/N2H4·H2O is 151.2 mAh/g at 1 and 142.7 mAh/g at 2,retaining nearly 91.1%and 89.6%of 158.4 mAh/g at 0.2.After 800 cycles at 0.2@RT,the capacity retention of GO/N2H4·H2O is nearly 95.3%of the initial capacity,however,rGO/AlP and rGO/NaBH4 are 91.1%and 89.6%,respectively.