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Developing advanced electrode materials for sodium ion batteries (SIBs) to meet the urgent need of high performance is still challenging. In this study, a novel SIBs negative electrode composite material (N/(Ni, Co)Se 2 NFCs@RGOA) was prepared by loading N-doped bimetal derived nano-framework cubes (N/(Ni, Co)Se 2 NFCs) on reduced graphene oxide aerogel (RGOA). The nano-size and hollow cage structure of N/(Ni, Co)Se 2 NFCs cooperate with the layered branched carbon skeleton and porous structure of RGOA to accelerate the reaction kinetics, therefore alleviate the structure collapse caused by volume expansion, and boost the conductivity of the material. The characterization and electrochemical testing results show that the electrode material has remarkable electrochemical performance (reversible capacity of 497 mA h g−1 at 0.1 A g−1), capacity stability (395 mA h g−1 after 200 cycles) and excellent rate performance (389 mA h g−1 at the current density of 2 A g−1). The as designed electrode material will play a significant role to benefit the development of SIBs and advanced electrical storage applications. [Display omitted] • A novel N-doped Ni-Co bimetallic derived electrode material was prepared. • N/(Ni, Co)Se 2 NFCs@RGOA has hollow nano-framework cubic and porous structures. • The reversible capacity of N/(Ni, Co)Se 2 NFCs@RGOA at 0.1 A g−1 is 497 mA h g−1. • Electrode material exhibits excellent rate performance and capacity stability in SIBs. [ABSTRACT FROM AUTHOR]

In this study, a magnetic composite (Fe 3 O 4 @SiO 2 -APTES/GO/CNF) possessed three-dimensional network was prepared by electrostatic self-assembly method based on cellulose nanofiber (CNF)/graphene oxide (GO). The adsorption properties and mechanism of Fe 3 O 4 @SiO 2 -APTES/GO/CNF for methylene blue (MB) were investigated. The experimental results show that the composite material has an obvious three-dimensional network and can be quickly collected under the attraction of external magnets. When the mass ratio of CNF, GO, and Fe 3 O 4 @SiO 2 -APTES is 7: 3.5: 1, the adsorption effect of MB is optimal. Langmuir isothermal adsorption model and pseudo-second-order kinetic model can well describe the adsorption process of MB on the composites, the maximum adsorption capacity is up to 1447 mg g−1. It is satisfactory that the adsorption capacity for MB remains 83.53% of the original adsorbent after five cycles. The good adsorption and cyclic performance endow it with a broad application prospect in dye wastewater treatment. [Display omitted] • A simple electrostatic self-assembly method was used. • The maximum adsorption capacity of the composite for MB is 1447 mg g−1. • The adsorbent can be easily recycled by external magnets in only 20 s • The adsorption capacity of MB is 83.53% of the initial amount after 5 cycles. [ABSTRACT FROM AUTHOR]

Transition metal selenides have attracted much attention as electrode materials for Na-ion batteries (NIBs) because of their great potential as electric energy storage. Here, we report a facile strategy for synthesis of Cu-doped CoSe 2 nanoframe cubics (Cu-CoSe 2 NFCs) structures through standing aging, chemical etching and ion exchange. In the experiment, the Co-Co PBA cube was etched from eight corners into a hollow frame structure. This hollow frame structure provides a good solution for the ion diffusion effect of the sodium battery. After ion exchange, the presence of Se and Cu after ion exchange greatly increases the capacity of the electrode. The synthesized Cu-CoSe 2 NFCs electrode exhibits excellent reversible charge and discharge capacity (470 mAh g−1 at 0.1 A g−1). Even at a high current density of 2 A g−1, Cu-CoSe 2 NFCs can still provide an excellent specific capacitance of 387 mAh g−1. The presence of selenium and copper greatly increases the capacity of the electrode. The synthesized Cu-CoSe 2 NFCs electrode exhibits excellent reversible charge and discharge capacity (470 mAh g−1 at 0.1 A g−1). [Display omitted] • The hollow frame structure solves the ion diffusion effect of NIBs. • Se and Cu play a key role in increasing electrode capacity. • Cu-CoSe 2 NFCs electrode exhibit great sodium storage performance and cyclic stability. [ABSTRACT FROM AUTHOR]