Mechanical ball-milling preparation of fullerene/cobalt core/shell nanocomposites with high electrochemical hydrogen storage ability

Kinetics and mechanism effects of 2D carbon supports in hydrogen spillover composites

Extensive research has been performed using two-dimensional (2D) carbon materials as catalyst supports to achieve high-performance hydrogen storage composites through the hydrogen spillover phenomenon. However, the kinetics and mechanism effects of different support materials still need to be investigated. This study employed high-energy ball milling to fabricate Co1-xS/C60 and C1-xS/rGO composites with stable structures and abundant hydrogen storage sites. We explored the mechanism of hydrogen adsorption behavior through electrode kinetic studies and density functional theory calculations, revealing the intrinsic relationship between material composition, structure, and hydrogen diffusion kinetics. The 2D flakes of C60 and rGO support and connect C1-xS nanoparticles, providing electron transport pathways for the composites. Theoretically, the spherical C60 support with less steric hindrance showed a more vital ability to increase the hydrogen adsorption capacity, while kinetically, thin film rGO offers fast channels for hydrogen diffusion. These findings contribute to our understanding of hydrogen spillover and present opportunities to investigate the synergistic effects in 2D carbon-based composites.

Core-shell nanomaterials: Applications in energy storage and conversion

Materials with core-shell structures have attracted increasing attention in recent years due to their unique properties and wide applications in energy storage and conversion systems. Through reasonable adjustments of their shells and cores, various types of core-shell structured materials can be fabricated with favorable properties that play significant roles in energy storage and conversion processes. The core-shell material can provide an effective solution to the current energy crisis. Various synthetic strategies used to fabricate core-shell materials, including the atomic layer deposition, chemical vapor deposition and solvothermal method, are briefly mentioned here. A state-of-the -art review of their applications in energy storage and conversion is summarized. The involved energy storage includes supercapacitors, li-ions batteries and hydrogen storage, and the corresponding energy conversion technologies contain quantum dot solar cells, dye-sensitized solar cells, silicon/organic solar cells and fuel cells. In addition, the correlation between the core-shell structures and their performance in energy storage and conversion is introduced, and this finding can provide guidance in designing original core-shell structures with advanced properties.

Electrochemical Hydrogen Storage in Facile Synthesized Co@N-Doped Carbon Nanoparticle Composites

A Co@nitrogen-doped carbon nanoparticle composite was synthesized via a facile molecular self-assembling procedure. The material was used as the host for the electrochemical storage of hydrogen. The hydrogen storage capacity of the material was over 300 mAh g^-1 at a rate of 100 mAg^-1. It also exhibited superior stability for storage of hydrogen, high rate capability, and good cyclic life. Hybridizing metallic cobalt nanoparticle with nitrogen-doped mesoporous carbon is found to be a good approach for the electrochemical storage of hydrogen.

Chemical grafting of Co9S8 onto C60 for hydrogen spillover and storage

Metal modified C₆₀ is considered to be a potential hydrogen storage medium due to its high theoretical capacity. Research interest is growing in various hybrid inorganic compounds-C₆₀. While the design and synthesis of a novel hybrid inorganic compound-C₆₀ is difficult to attain, it has been theorized that the atomic hydrogen could transfer from the inorganic compound to the adjacent C₆₀ surfaces via spillover and surface diffusion. Here, as a proof of concept experiment, we graft Co₉S₈ onto C₆₀via a facile high energy ball milling process. The Raman, XPS, XRD, TEM, HTEM and EELS measurements have been conducted to evaluate the composition and structure of the pizza-like hybrid material. In addition, the electrochemical measurements and calculated results demonstrate that the chemical "bridges" (C-S bonds) between these two materials enhance the binding strength and, hence, facilitate the hydriding reaction of C₆₀ during the hydrogen storage process. As a result, an increased hydrogen storage capacity of 4.03 wt% is achieved, along with a favorable cycling stability of ∼80% after 50 cycles. Excluding the direct hydrogen storage contribution from Co₉S₈ in the hybrid paper, the hydrogen storage ability of C₆₀ was enhanced by 5.9× through the hydriding reaction caused by the Co₉S₈ modifier. Based on these experimental measurements and theoretical calculations, the unique chemical structure reported here could potentially inspire other C₆₀-based advanced hybrids.

Flattening sol–gel nanospheres into a carbon sheet-intercalated cobalt/carbon/cobalt sandwich-nanostructure

Uniform cobalt/carbon/cobalt sandwich-like nanosheet stacks have been constructed by using sol–gel nanospheres covered with Co^II–Co^III–LDH as a precursor.

Hybridization of inorganic CoB noncrystal with graphene and its Kubas-enhanced hydrogen adsorption at room temperature

In this work an archetypical hybrid material has been prepared by the reaction of an inorganic CoB noncrystal with graphene by a high-energy ball-milling process, which showed an enhanced electrochemical hydrogen storage ability induced by the Co–B–C structure.

Hydrogen storage in a chemical bond stabilized Co9S8-graphene layered structure

With the high energy ball milling method, a Co9S8-decorated reduced graphene oxide (RGO) composite, which shows excellent hydrogen storage capacity, has been successfully fabricated with a well-organized layered structure. Moreover, the stabilized mechanism of the well-organized layered structure is investigated and attributed to the strong interactions between Co9S8 and defective RGO. The C-S bond interaction is identified and the hydrogen storage process is also studied with different analysis methods. Finally, an optimized Co9S8 to RGO weight ratio of 6:1 shows excellent electrochemical performances in terms of the excellent cycling stability and competitive hydrogen storage capacity of 4.86 wt%.