General Synthesis of Transition‐Metal Oxide Hollow Nanospheres/Nitrogen‐Doped Graphene Hybrids by Metal–Ammine Complex Chemistry for High‐Performance Lithium‐Ion Batteries

Abstract

We present a general and facile synthesis strategy, on the basis of metal-ammine complex chemistry, for synthesizing hollow transition-metal oxides (Co O , NiO, CuO-Cu O, and ZnO)/nitrogen-doped graphene hybrids, potentially applied in high-performance lithium-ion batteries. The oxygen-containing functional groups of graphene oxide play a prerequisite role in the formation of hollow transition-metal oxides on graphene nanosheets, and a significant hollowing process occurs only when forming metal (Co , Ni , Cu , or Zn )-ammine complex ions. Moreover, the hollowing process is well correlated with the complexing capacity between metal ions and NH molecules. The significant hollowing process occurs for strong metal-ammine complex ions including Co , Ni , Cu , and Zn ions, and no hollow structures formed for weak and/or noncomplex Mn and Fe ions. Simultaneously, this novel strategy can also achieve the direct doping of nitrogen atoms into the graphene framework. The electrochemical performance of two typical hollow Co O or NiO/nitrogen-doped graphene hybrids was evaluated by their use as anodic materials. It was demonstrated that these unique nanostructured hybrids, in contrast with the bare counterparts, solid transition-metal oxides/nitrogen-doped graphene hybrids, perform with significantly improved specific capacity, superior rate capability, and excellent capacity retention.

Hierarchical Zn1.67 Mn1.33 O4 /graphene nanoaggregates as new anode material for lithium-ion batteries

“…Among the solutions, nanostructuring has been regarded as a promising method that shortens the diffusion path of lithium ions and introduces sufficient space for stress relaxation in the original structure . In addition, nanostructured materials have higher specific surface area than bulk materials, which can result in higher performance because of the increased contact surface with the electrolyte.…”

Reduced Graphene Oxide-Supported Co3O4 Nanocomposite Bifunctional Electrocatalysts for Glucose–Oxygen Fuel Cells

“…29 Upon heating the complex under hydrothermal treatment, Co 3 O 4 was formed. 30 Meanwhile, the GO present in the solution effectively prevented the aggregation of Co 3 O 4 . The hydrothermal method favored in situ formation of Co 3 O 4 and GO reduction.…”

“…The oxidized product was not simply a [Co­(NH 3 ) 6 ] 3+ complex but a binuclear peroxide complex [(NH 3 ) 5 Co­(III)­O 2 Co­(III)­(NH 3 ) 5 ] 4+ . Upon heating the complex under hydrothermal treatment, Co 3 O 4 was formed . Meanwhile, the GO present in the solution effectively prevented the aggregation of Co 3 O 4 .…”

Fully water-blown polyisocyanurate-polyurethane foams with improved mechanical properties prepared from aqueous solution of gelling/ blowing and trimerization catalysts

“…Extraction of copper(II) and zinc(II) in an ammonia solution leads to the investigation of copper-and zinc-ammonia complex structures in an ammonia solution (22)(23)(24)(25). The chemistry of metal-ammonia complexes was applied to prepare hollow copper-and zinc-oxides/nitrogen doped graphene hybrids using metal-ammonia complexes as precursors (26). The [Cu(NH 3 ) x ] 2+ form of heulandite (CuammHEU) was prepared by the treatment of the Na-form of natural heulandite crystals with the copper-ammonia complex solution.…”