Bo Quan

In this work, we reported a facile approach to prepare a uniform copper ferrite nanoparticle-attached graphene nanosheet (CuFe2O4-GN). A one-step solvothermal method featuring the reduction of graphene oxide and formation of CuFe2O4 nanoparticles was efficient, scalable, green, and controllable. The composite nanosheet was fully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), which demonstrated that CuFe2O4 nanoparticles with a diameter of approximately 100 nm were densely and compactly deposited on GN. To investigate the formation mechanism of CuFe2O4-GN, we discussed in detail the effects of a series of experimental parameters, including the concentrations of the precursor, precipitation agent, stabilizer agent, and graphene oxide on the size and morphology of the resulting products. Furthermore, the electrochemical properties of the CuFe2O4-GN composite were studied by cyclic voltammetry and galvanostatic charge-discharge measurements. The composite showed high electrochemical capacitance (576.6 F·g(-1) at 1 A·g(-1)), good rate performance, and cycling stability. These results demonstrated that the composite, as a kind of electrode materials, had a high specific capacitance and good retention. The versatile CuFe2O4-GN holds great promise for application in a wide range of electrochemical fields because of the remarkable synergistic effects between CuFe2O4 nanoparticles and graphene.

Abstract Sodium‐ion batteries (SIBs) have attracted enormous attention in recent years due to the high abundance and low cost of sodium. However, in contrast to lithium‐ion batteries, conventional graphite is unsuitable for SIB anodes because it is much more difficult to intercolate the larger Na ions into graphite layers. Therefore, it is critical to develop new anode materials for SIBs for practical use. Here, heteroatom‐doped graphene with high doping levels and disordered structures is prepared using a simple and economical thermal process. The solvothermal‐derived graphene shows excellent performance as an anode material for SIBs. It exhibits a high reversible capacity of 380 mAh g −1 after 300 cycles at 100 mA g −1 , excellent rate performance 217 mAh g −1 at 3200 mA g −1 , and superior cycling performance at 2.0 A g −1 during 1000 cycles with negligible capacity fade.

Solvothermal processes are considered efficient approaches for the gram-scale production of graphene. Further modification of graphene by chemical doping is an important approach to tailor its properties. In this work, we successfully synthesized sulfur-doped graphene by using a solvothermal method with dimethyl sulfoxide as a precursor, which is a common laboratory reagent. Nitrogen-doped graphene was produced to demonstrate the generality of this process. These heteroatom-doped graphene materials exhibited high surface areas and high contents of heteroatoms. Furthermore, the lithium-ion storage properties and oxygen reduction reaction catalytic activity of these materials were also investigated. The success of this approach might facilitate the development of other advanced graphene-based materials with relative simplicity, scalability, and cost effectiveness for use in various potential applications.

We introduce a simple process to synthesize few-layered MoS(2) nanosheets supported on coaxial carbon nanotubes through an L-cysteine-assisted hydrothermal route, in which L-cysteine, a cheap and ordinary amino acid, plays a fundamental role in controlling the morphology of the hybrid material and the binder to help the growth of MoS(2) nanosheets on the surface of the carbon nanotubes. It is also demonstrated that the polypeptide formed by L-cysteine can be transformed into amorphous carbon by heat treatment under an inert atmosphere. The materials exhibit high capacity and excellent cycling performance when used as anode materials for lithium ion batteries. The specific capacity of a composite with 1 : 4 molar ratio of MoS(2) to carbon nanotubes is 736.5 mAh g(-1) after the first cycle, increased for several initial cycles, and remains at 823.4 mAh g(-1) even after 30 cycles, when cycled at a current density of 100 mA g(-1). At a very high current density of 1600 mA g(-1), the material shows a stable capacity of approximately 530 mAh g(-1) after 30 cycles. The noteworthy improvement in the electrochemical performance of the material can be attributed to their unique structure and the synergistic effects of amorphous carbon and few-layered MoS(2).