Hydrothermal synthesis and structure evolution of hierarchical cobalt sulfidenanostructures

Abstract

Hierarchical and well-defined cobalt sulfide with flower-like, cube-like, ball-like, and surface hollowed-out nanostructures were successfully prepared by a facile one-pot hydrothermal synthesis approach, employing Co(NO(3))(2)·6H(2)O as a cobalt precursor and thiourea as a sulfur source. The morphologies of these structures can be easily controlled by simply adjusting the molar ratio of reactants and solvents, reaction time, reaction temperature, and ligand types. Thiourea plays two important roles in the growth process of CoS nanostructures. First, it is decomposed to produce S(2-) for the final formation of CoS. On the other hand, it serves as a structure-directing agent to control the crystalline growth of CoS. The electrochemical capacitance performances of the CoS nanostructures were studied, and the flower-like CoS nanostructures show the best charge-discharge performance among all CoS products with the highest specific capacitance values of 389 F g(-1) at current density of 5 mA cm(-2), and 277 F g(-1) at higher current density of 50 mA cm(-2).

Electrodeposited polymer encapsulated nickel sulphide thin films: frequency switching material

“…In the spectra the peak for Ni-S stretching was not observed. This might be due to the compact encapsulation of NiS nanoparticles by PVP which arrests any vibrational mode of excitation of the NiS, similar results were obtained by Dong et al for chemical synthesis of CoS with PVP [29]. Hence, it is clear that when PVP and TAA co-exist in the reaction system, PVP plays the dominant role in controlling the growth of NiS.…”

Electrochemically Synthesis of Nickel Cobalt Sulfide for High‐Performance Flexible Asymmetric Supercapacitors

“…From the Figure 5a, The Ni–Co–S/GF electrode gave rise to an anodic and a cathodic peak at 0.4 and 0.14 V, respectively, corresponding to the redox reactions of Ni–Co–S/GF. In addition, the OH − ions play a significant role in the electrochemical oxidation and reduction of nickel sulfides and cobalt sulfides as reported previously 36. Rate capability is an important parameter estimating the power density of electrochemical capacitors.…”

Solvent-controlled morphology of bismuth sulfide for supercapacitor applications

“…In our study, we demonstrate that the use of a suitable solvent or mixture of solvents enables the formation of nanometer-sized Bi 2 S 3 with unique structural forms, including microspheres composed of bean-like units (Bi 2 S 3 -W) and homogeneous nanospheres (Bi 2 S 3 -EG/W). Recently, a solvothermal synthesis in a mixed solvent system (including water as a system component) has been shown to be an effective approach for the synthesis of nanostructures with novel shapes and uniform sizes, such as skeleton spheres, cubes, yarn balls and roses [39,40,47]. As previously reported [40], adjusting the solvent components and their ratios allows the growth of a metal sulfide with a diverse morphology to be controlled.…”

“…However, optimizing the solvothermal process by altering the solvent mixture has not attracted much attention. According to previous reports [39,40], syntheses in mixed solvents favor the formation of nanostructures with more uniform sizes and uncommon architectures compared with syntheses in single solvents. Most reports have focused on the synthesis of Bi 2 S 3 in water [19,22,23,25,27,34,38,41].…”