以甲壳胺(CTS)和钴、铁盐作有机前体与反应物,采用共沉淀法制备了CTS/钴铁层状双金属氢氧化物复合物.样品经过氩气氛、空气氛煅烧,生成氮掺杂部分石墨化碳/钴铁氧化物复合材料(N-PGC/CoFe-TMOs).CTS热解且被过渡金属催化生成部分石墨化碳,同时原位氮掺杂,氮/碳原子比例约为1/18.N-PGC/CoFe-TMOs具有大孔和介孔结构,用作超级电容器电极材料兼有双电层电容与赝电容特征.在2 A·g-1电流密度下,复合物比电容达到671.1 F·g-1,远大于纯钴铁氧化物比电容283.3 F·g-1,复合物具有典型的协同效应,电流密度增加到10A·g-1时,N-PGC/CoFe-TMOs比电容为573.3 F·g-1,经过5000次充放电循环,复合物比电容保留率为66.4％.制备方法简便、通用,煅烧过程可一步制备氮掺杂的部分石墨化碳并与过渡金属氧化物复合,产物电化学性能优异.%With the renewable biopolymer chitosan (CTS) as a structure directing agent and organic precursor,facile coprecipitation method was applied for the cobalt and iron nitrates in solution to prepare CTS/cobalt iron layered double hydroxides composite.The LDHs sample was calcinated in a tubular furnace under Ar atmosphere via heating ramps of 5 ℃ · min-1 from room temperature to 200 ℃ and kept for 1 h,then heated to 600 ℃ and remained for 2 h.After the sample was cooled naturally to room temperature,it was heated again to 250 ℃ under air atmosphere and kept for 12 h to oxidize the transition metal elements.As a result,nitrogen-doped partially graphitized carbon/cobalt iron transition metal oxides nanocomposite (N-PGC/CoFe-TMOs) was obtained.X-ray diffraction,Raman spectroscopy,N2 adsorption-desorption analysis,scanning electron microscopy,high resolution transmission electron microscopy,energy-dispersive X-ray spectroscopy were carried out to characterize the structure,morphology and elemental composition of the product.Cyclic voltammetry and galvanostatic charge-discharge measurements were conducted to evaluate the electrochemical properties of N-PGC/CoFe-TMOs.Experimental results showed that the CTS precursor was converted into partially graphitized carbon by pyrolysis with the help of catalysis graphitization action of transition metal elements.At the same time,the derived carbon material was successfully doped with nitrogen in situ and the N/C atomic ratio was about 1/18.N-PGC/CoFe-TMOs possessed bimodal porous texture including macropores and mesopores,exhibited combined characters of electrical double-layer supercapacitor and pseudocapacitor when used as supercapacitor electrode material.At the current density of 2 A·g-1,N-PGC/CoFe-TMOs composite delivered a large discharge capacity of 671.1 F·g-1,far higher than 283.3 F·g-1 of pure cobalt iron oxides,indicating the typical synergistic effect between nitrogen-doped partially graphitized carbon and transition metal oxides.Even at the high current density of 10 A·g-1,N-PGC/CoFe-TMOs composite still remained a specific capacity of 573.3 F·g-1.After 5000 charge-discharge cycles at 10 A·g-1,the capacitance retention was 66.4％.The reported synthesis method in this work is simple and universal,and calcination process combines the nitrogen-doping,partially graphitized carbon formation with redox-active transition metal oxides synthesis in one step,endowing the product with excellent electrochemical properties.
展开▼
