Qiushi Sun

Facile synthesis of hierarchical CoMoO4@NiMoO4 core–shell nanosheet arrays on nickel foam as an advanced electrode for asymmetric supercapacitors

Hierarchical CoMoO4@NiMoO4 core–shell nanosheet arrays were successfully grown on nickel foam via a facile two-step hydrothermal method followed by calcination treatment. With an ordered core–shell nanostructure and a desired composition, the optimized CoMoO4@NiMoO4 composite electrode exhibited a high specific capacitance of 1639.8 F g−1 (3.30 F cm−2) and an excellent cycling stability with a 95% retention rate at a high current density of 20 mA cm−2 after 3000 cycles. Additionally, an asymmetric supercapacitor (ASC) was assembled with CoMoO4@NiMoO4 nanosheet arrays/Ni foam as the positive electrode and activated carbon (AC) as the negative electrode, which displayed an energy density of 28.7 W h kg−1 at a power density of 267 W kg−1. The remarkable electrochemical performance indicated that the CoMoO4@NiMoO4 composite was a promising electrode material and had great application potential for energy storage.

The synthesis of hierarchical ZnCo2O4@MnO2 core–shell nanosheet arrays on Ni foam for high-performance all-solid-state asymmetric supercapacitors

Hierarchical ZnCo2O4@MnO2 core–shell nanosheet arrays were successfully synthesized on Ni foam via a facile hydrothermal method followed by a calcination process. The fabricated ZnCo2O4@MnO2 electrode exhibited a specific capacitance as high as 2170.00 F g−1 (2.60 F cm−2) at a current density of 3 mA cm−2 in a 1 M KOH solution. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) device fabricated with the as-prepared ZnCo2O4@MnO2 as the positive electrode and activated carbon (AC) as the negative electrode in the PVA/KOH gel electrolyte achieved a high energy density of 29.41 W h kg−1 at a power density of 628.42 W kg−1 and retained 95.3% of its initial capacitance after 3000 cycles at a high current density of 10 mA cm−2. With the smart design and remarkable electrochemical properties, the hierarchical ZnCo2O4@MnO2 core–shell nanosheet arrays on Ni foam demonstrated great potential for further applications in the energy storage field.

A facile one-step hydrothermal approach to synthesize hierarchical core–shell NiFe2O4@NiFe2O4 nanosheet arrays on Ni foam with large specific capacitance for supercapacitors

In this contribution, NiFe2O4@NiFe2O4 nanosheet arrays (NSAs) with three-dimensional (3D) hierarchical core–shell structures were synthesized by a facile one-step hydrothermal method and they were used as electrode materials for supercapacitors (SCs). The NiFe2O4@NiFe2O4 composite electrode showed a high specific capacitance of 1452.6 F g−1 (5 mA cm−2). It also exhibited a superior cycling stability (93% retention after 3000 cycles). Moreover, an asymmetric supercapacitor (ASC) was constructed utilizing NiFe2O4@NiFe2O4 NSAs and activated carbon (AC) as the positive and negative electrode, respectively. The optimized ASC shows extraordinary performances with a high energy density of 33.6 W h kg−1 at a power density of 367.3 W kg−1 and an excellent cycling stability of 95.3% capacitance retention over 3000 cycles. Therefore, NiFe2O4@NiFe2O4 NSAs have excellent pseudocapacitance properties and are good electrode materials for high energy density.

Pressure quenching: a new route for the synthesis of black phosphorus

Methods to synthesize black phosphorus (BP) have been studied over the last few decades with several challenges remaining to be solved. In this paper, BP flakes were synthesized using a novel method, which we named as “Pressure Quenching” approach. Briefly, BP was obtained from red phosphorus (RP) through a controllable phase transition under conditions below 0.4 GPa and 580 °C. The mechanism was investigated in detail via a decompression process at fixed temperature with the phase transition exhibiting an energy barrier dependence. Meanwhile, an extra tunable energy was generated by pressure quenching as a supplement for the phase transition. Therefore, the transition from RP to BP could be easily controlled by tuning the applied pressure.

A novel polyhedron-based metal–organic framework with high performance for gas uptake and light hydrocarbon separation

A novel polyhedron-based metal-organic framework [(CH3)2NH2]2[Zn3(TADIPA)2(DMF)2]·4DMF (JLU-Liu40), which possesses three types of cages with different shapes and sizes, has been successfully synthesized. The framework of JLU-Liu40 is constructed by two inorganic secondary building units (SBUs) of 4-connected square binuclear Zn-paddlewheel and 4-connected tetrahedron mononuclear Zn unit and one organic SBU, which has abundant Lewis basic sites (LBSs), and the framework can be simplified as a pair of 3-connected triangle geometries. Moreover, JLU-Liu40 shows a new (3, 4, 4)-connected topology with the Schläfli symbol {72, 9}2{74, 82}. With the benefit of its high density of open metal sites (OMSs) and LBSs, JLU-Liu40 shows good adsorption ability for some small gases such as N2, CO2, CH4, C2H6 and C3H8. In addition, the theoretical ideal adsorbed solution theory (IAST) calculation indicates that JLU-Liu40 should be a promising material for light gas separation.

Acetic Acid Assistant Hydrogenation of Graphene Sheets with Ferromagnetism

Ferromagnetism of pure carbon-based materials has been widely researched for several years. In therocially and experimentally, semi-hydrogenation graphene sheets exhibit ferromagnitism, which is related to the degree of hydrogenation. Here we reported the controllable hydrogenation of graphene using ball-milling method with acetic acid as hydrogenating agent. The hydrogenation graphene sheets were characterized by means of transmission electron microscopy(TEM), Raman spectroscopy and X-ray photoelectron spectroscopy, and magnetic measurement. The relusts of Raman spectroscopy demonstrate that the relative intensity of D band increases with the hydrogenation degree. The resluts of magnetic meansurement indicate the maximal magnetic moment of 0.274 A·m2/kg at 2 K for semi-hydrogenation graphene.