溶剂热法合成纳米立方状Co_3O_4及其电容特性研究

Solvothermal Synthesis and Capacitance Performance of Co_3O_4 Nanocubes

以聚乙二醇为分散剂,在水-正丁醇体系中采用溶剂热法合成纳米立方状Co_3O_4。采用IR、XRD和TEM等手段对前驱物及产物的物相和形貌进行表征,对溶剂热法合成Co_3O_4的反应机理进行初步研究,并以Scherrer公式计算出样品平均晶粒尺寸为21.6nm。通过循环伏安、恒流充放电、交流阻抗等测试对Co3O4电极的电化学性能进行表征。结果表明,在2mol·L^(-1)KOH溶液中,-0.4￣0.46V(vs.SCE)电位范围内,立方状Co_3O_4具有良好的电容特性、大电流充放电性能及循环稳定性。单电极初始比容量达333.21F·g^(-1),1000次循环后样品比容量保持69%。通过XRD测试分析Co_3O_4循环前后的物相转变,结果表明经过1000次循环后Co_3O_4仍保持为立方晶型。

Co3O4 nanocubes were synthesized by solvothermal method using polyethylene glycol 20 000 as dispersant in water and n-butanol solvent system. The structure and morphology of the precursor and product were charactrized by IR, X-ray diffraction（XRD） and transmission electron microscopy（TEM）. The formation mechanism of Co3O4 was also discussed preliminary. The average grain size of the product was 21.6 nm calculated by Scherrer formula. Electrochemical properties of Co3O4 electrode were performed by cyclic vohammetry （CV）, galvanostatic charge/ discharge and alternating current （AC） impedance method. The results indicate that the Co3O4 nanocubes show excellent capacitive performance, charge/discharge ability at high current density and cycling stability in 2 mol·L^-1 KOH electrolyte in the potential range of -0.4 -0.46 V （vs SCE）. The initial specific capacitance of single Co3O4 electrode reaches 333.21 F·g^-1 and 69% is maintained after 1 000 cycles. The phase transformation of Co3O4before and after cycling was studied by XRD test. The results indicate that the cubic phase of Co3O4 is maintained after 1 000 cycles.