镍基MOF电极材料物理超声改性及电化学性能

采用水热法合成了以4,4′-联苯二甲酸(BPDC)为配体的Ni-金属有机框架(MOF),利用低成本、无污染的物理超声法在不改变Ni-MOF晶体结构的前提下对其进行改性,使块状Ni-MOF表面产生孔隙,改善Ni-MOF表面微/纳米结构,提高其电化学性能。通过扫描电子显微镜(SEM)图、X射线衍射(XRD)谱、循环伏安(CV)曲线和恒电流充放电(GCD)曲线分析了改性前后Ni-MOF的微结构形貌和电化学性能。结果表明,经过超声处理后,Ni-MOF的比表面积从40.6 m^2·g^-1增加到65.8 m^2·g^-1,平均孔径从12 nm增加到22 nm。在0.5 A·g^-1电流密度下,超声处理后Ni-MOF电极比电容从420 F·g^-1增加到515 F·g^-1,提高了22.6%,电荷转移电阻明显降低,从25.11Ω降低到15.51Ω。因此,物理超声法可有效改善Ni-MOF表面微/纳米结构,提高其电化学性能。

Modification by Physical Ultrasonic Treatment and Electrochemical Properties of Nickel-Based MOF Electrode Materials

The Ni-metal-organic framework(MOF)with 4,4′-biphenyldicarboxylate(BPDC)as ligand was synthesized by the hydrothermal method.On the premise of maintaining the crystal structure of the Ni-MOF,the Ni-MOF was modified by the low-cost and pollution-free physical ultrasonic method,which made pores produce on the surface of the bulk Ni-MOF,improved the micro-/nano-structure of the Ni-MOF surface and enhanced its electrochemical properties.The microstructure morphologies and the electrochemical properties of the Ni-MOF before and after the modification were analyzed by the scanning electron microscope(SEM)images,X-ray diffraction(XRD)patterns,cyclic voltammetry(CV)curves and galvanostatic charge-discharge(GCD)curves.The results show that after the ultrasonic treatment,the specific surface area of the Ni-MOF increases from 40.6 m^2·g^-1 to 65.8 m^2·g^-1,and the average pore diameter increases from12 nm to 22 nm.Besides,the specific capacitance of the ultrasonicated Ni-MOF electrode increases from420 F·g^-1 to 515 F·g^-1 at a current density of 0.5 A·g^-1,increasing by 22.6%,and the charge transfer resistance decreases significantly from 25.11Ωto 15.51Ω.Therefore,the physical ultrasonic method can effectively improve the Ni-MOF surface micro-/nano-structure and enhance its electrochemical properties.