Hierarchical Hollow Co₉S₈ Microspheres: Solvothermal Synthesis, Magnetic, Electrochemical, and Electrocatalytic Properties

Abstract

A simple solvothermal route in a binary solution of triethylenetetramine (TETA) and deionized water (DIW) has been used to synthesize hierarchical hollow Co(9)S(8) microspheres with high surface area (80.38 m(2) g(-1)). An appropriate volume ratio of TETA:DIW has been found to be essential for the formation of hollow Co(9)S(8) microspheres. The magnetic study indicated that the Co(9)S(8) hollow microspheres are paramagnetic at high temperature and antiferromagnetic at low temperature. The oxygen reduction reaction experiments demonstrated that the onset potential of the Co(9)S(8) sample is 0.88 V, which is comparable to the value predicted for Co(9)S(8) (0.74 V) from the theoretical simulation. The discharge capability of Co(9)S(8) hollow microspheres as cathode materials for lithium ion batteries and their electrocatalytic activity for the oxygen reduction reaction (ORR) have been studied.

Preparation of Yolk‐Shell and Filled Co9S8 Microspheres and Comparison of their Electrochemical Properties

“…The former could be associated with the oxidation of metallic Co, while the latter could be related to the oxidation of the SEI. [22,41,42] The peaks at 0.7 V and 1.4 V were barely observed from the second cycle onwards. The CV curves of the subsequent scans almost overlapped with those of the second scan, thus indicating the excellent electrochemical reversibility of the yolk-shell Co 9 S 8 microspheres.…”

“…The strong cathodic peak at around 1 V could be attributed to the reduction of Co 9 S 8 to Co according to the reaction: Co 9 S 8 + 16 Li + + 16 e À ! 8 Li 2 S + 9 Co. [22,41,42] The weak peak at around 0.7 V could be attributed to the electrolyte decomposition and the formation of a solid-electrolyte interface (SEI) layer. [41,42] In subsequent cycles, the strong cathodic peak slightly shifted to higher voltage ranges.…”

“…[15][16][17][18][19][20][21][22][23][24][25][26][27][28] Recently, cobalt sulfides have been investigated as electrode materials for Liion batteries (LIBs) because of their high theoretical capacity. [22][23][24][25][26][27][28] However, electrodes based on cobalt sulfide have a few inherent limitations such as poor cycle stability and a large volume change during Li-ion insertion/extraction.…”

Porous NiCo2S4 Networks as Electrodes for Electrochemical Supercapacitors

“…The binding energy at 169.92 eV is corresponding to the shakeup satellite. 35 According to the XPS analysis, the near-surface of the NiCo 2 S 4 samples were successfully synthesized. Figure 4 shows the nitrogen adsorption-desorption isotherm curve and the corresponding pore size distribution plot of the NiCo 2 S 4 nanomaterials.…”

NiS Hollow Spheres for High‐Performance Supercapacitors and Non‐Enzymatic Glucose Sensors

“…[25][26][27] Transition metal chalcogenides are of great interest as semiconductor functional materials owing to their wide potential applications in various fields such as magnetic devices, electrode materials in electronic devices, catalysts, etc. [28][29][30][31] Among a variety of transition metal sulfides, NiS is a promising energy storage material, and was found to have a potential application as electrode material in supercapacitors. There have been considerable research efforts devoted to the use of NiS for supercapacitors, due to its good pseudocapacitive behavior, practical availability, and low cost.…”