Xiaochuan Duan

Rational synthesis of ZnMn2O4 porous spheres and graphene nanocomposite with enhanced performance for lithium-ion batteries

Currently, tremendous efforts have been focused on developing high-performance anode materials for lithium-ion batteries (LIBs). In this work, we develop an effective strategy to synthesize a nanocomposite of ZnMn2O4 porous spheres and graphene (ZMO-G PSs) as an advanced anode material for high-performance LIBs. SEM and TEM characterizations reveal that the ZMO PSs are tightly wrapped by graphene sheets and uniformly distributed within the graphene matrix. Owing to the rational combination of the merits of both ZMO PSs and graphene, the as-prepared ZMO-G PSs nanocomposite exhibits significant enhanced LIB performance with high reversible capacity, long cycle life and good rate performance. Remarkably, the nanocomposite exhibits a high reversible capacity of 926.4 mA h g−1 after 100 cycles at a current density of 200 mA g−1, which is much higher than that of pure ZMO PSs (493.3 mA h g−1). Moreover, a high capacity of 560.8 mA h g−1 can be retained at a high current density of 1200 mA g−1. These electrochemical results suggest the ZMO-G PSs nanocomposite could be a promising anode material in energy storage applications for high-performance LIBs.

Rational synthesis of metal–organic framework composites, hollow structures and their derived porous mixed metal oxide hollow structures

Metal–organic frameworks (MOFs) have attracted considerable attention for their important applications. Recently, significant efforts have been devoted to constructing hollow MOF structures and integrating MOFs with other functional materials to further enhance the inherent performance and endow them with new functions. However, it still remains a big challenge to synthesize well-defined MOF composites and MOF hollow structures, especially those with structural and compositional complexity. In this work, we demonstrate a chemical transformation method to synthesize unique MOF composites, as well as hollow and complex hollow MOF structures. This method could intelligently overcome the difficulty that is caused by the possible lattice mismatch between MOFs and other functional materials. Impressively, a series of unique MOF@MOF core–shell structures, MOF composites, MOF hollow and complex hollow structures are successfully synthesized. Moreover, porous mixed metal oxide hollow and complex structures are obtained by annealing the corresponding MOF hollow and complex hollow structures in air. We anticipate that these unique MOF composites, hollow structures and the derived porous mixed metal oxide hollow structures could find promising applications in many other fields. As an example, NiFe oxide cube-in-box complex hollow nanostructures are evaluated as anode materials for lithium-ion batteries (LIBs), which exhibit enhanced electrochemical performance compared to the simple nanobox counterparts.

3D hierarchical CuO mesocrystals from ionic liquid precursors: towards better electrochemical performance for Li-ion batteries

CuO mesocrystals have been synthesized by nonclassical crystallization in the presence of an ionic liquid and n-butylamine under hydrothermal conditions. The resultant mesocrystals are composed of anisotropic nanosheets and nanorods as building blocks and possess distinct 3D hierarchical superstructure exposed {001} crystal planes. The mechanisms underlying the sequential formation of the mesocrystals are as follows: amorphous particles first appeared under a high degree of supersaturation according to the Ostwald rule of stages; then, nanosheet subunits were favored to form due to the protection of the {001} planes by n-butylamine molecules and etching of the {010} planes by a hydrolysis reaction, leading to the formation of a large number of dangling bonds in the {010} planes. Therefore, the ionic liquid can interact with these primary particles to facilitate a self-assembled superstructure by π–π interactions along the [010] direction due to the highly ionic nature, resulting in a 3D framework structure of primary particles composed of nanosheet and nanorod subunits by oriented attachment. Moreover, owing to the inherent porosity associated with well-defined nanoparticle orientation, the 3D hierarchical CuO mesocrystals achieved a higher electrochemical property as anodes for Li-ion batteries, surpassing the performance of CuO nanosheets and CuO nanorods. The unique characteristics of the hierarchical mesostalline electrodes show an ideal geometry to form a stable SEI film, which offers a facile route for designing high-performance electrodes for long-life Li-ion batteries.

Ionic liquid-assisted fabrication of copper hydroxyphosphate nanocrystals with exposed {100} facets for enhanced photocatalytic activity.

Libethenite Cu2PO4OH nanocrystals with different morphologies were prepared by an ionic liquid-assisted hydrothermal route, and were further investigated as photocatalysts under visible-light irradiation. The Cu2PO4OH elongated truncated bipyramids exposing {100} facets exhibit superior photocatalytic activity compared to other particles, which can be attributed to the presence of 100% Cu5c atoms on {100} facets. It is highly expect this research can provide a useful fundamental understanding of shape-dependent photocatalytic performance of copper hydroxyphosphate.