پديدآورندگان :
Abbasi Laleh Electroanalytical Chemistry Research Laboratory, Faculty of Chemistry, University of Guilan, Rasht , Arvand Majid arvand@guilan.ac.ir Electroanalytical Chemistry Research Laboratory, Faculty of Chemistry, University of Guilan, Rasht;
كليدواژه :
MnCo2S4 , nanosheet , hydrothermal , supercapacitors
چكيده فارسي :
In recent years, supercapacitors have been extensively developed as a unique class of energy storage devices due to their high power density, fast charge-discharge rate and long-term stability [1-3]. In this respect, ternary transition metal sulfides are promising as new electrode materials due to their higher energy storage capacity [4]. In this study, sulphospinel MnCo2S4 nanosheet arrays were in situ grown on Ni foam substrate through a facile two-step hydrothermal method. In a typical synthesis, a 60 mL mixed solution of 16 mM MnSO4·H2O, 33 mM Co(NO3)2·6H2O and 100 mM hexamethylenetetramine was added to a Teflon-lined stainless steel autoclave with a cleaned Ni foam and heated at 90 ℃ for 10 h to obtain Mn-Co precursor on Ni foam. After that, the substrate with loaded products was dried at 60 °C for further characterization. Then, in order to obtain MnCo2S4, a 75 mL solution of 25 mM Na2S was added to a Teflon-lined stainless steel autoclave with Ni foam supported Mn-Co precursor and maintained at 120 °C for 8 h. After the solution was subsequently cooled naturally, the as-synthesized electrode was washed with deionized water and dried at 60 ℃ for 5 h. XRD, SEM and TEM images confirmed the preparation of MnCo2S4 nanosheet arrays. The electrochemical experiments of obtained electrode were carried out in a three-electrode cell in 2 M KOH electrolyte, with Ag/AgCl, platinum plat and the Ni foam as the reference, counter and working electrodes, respectively. The resultant MnCo2S4 electrode delivered high areal capacitance of 5.43 F cm-2 at a current density of 1 mA cm-2. Additionally, with a 20-fold increase in current density from 1 to 20 mA cm-2, 61.87% of the initial capacitance was retained in the MnCo2S4 electrode, indicating its high rate capability which is significant in practical supercapacitor applications. Owing to the unique structural features, the as obtained MnCo2S4 nanosheet is considered as an effective electrode for the next generation energy storage device.
