Sodium-ion batteries (SIBs) are considered as a promising alternative to lithium-ion batteries, due to the abundant reserves and low price of Na sources. To date, the development of anode materials for SIBs is still confronted with many serious problems. In this work, encapsulation-type structured MoSe 2 @hollow carbon nanosphere (HCNS) materials assembled with expanded (002) planes few-layer MoSe 2 nanosheets confined in HCNS are successfully synthesized through a facile strategy. Notably, the interlayer spacing of the (002) planes is expanded to 1.02 nm, which is larger than the intrinsic value of pristine MoSe 2 (0.64 nm). Furthermore, the few-layer nanosheets are space-confined in the inner cavity of the HCNS, forming hybrid MoSe 2 @HCNS structures. When evaluated as anode materials for SIBs, it shows excellent rate capabilities, ultralong cycling life with exceptional Coulombic efficiency even at high current density, maintaining 501 and 471 mA h g −1 over 1000 cycles at 1 and 3 A g −1 , respectively. Even when cycled at current densities as high as 10 A g −1 , a capacity retention of 382 mA h g −1 can be achieved. The expanded (002) planes, 2D few-layer nanosheets, and unique carbon shell structure are responsible for the ultralong cycling and high rate performance.

Organic electrode materials play a crucial role in environmentally friendly and sustainable lithium-ion batteries (LIBs) due to their abundance, high theoretical capacity, inexpensiveness, and recyclability. However, critical issues such as fewer redoxactive sites and poor structural stability limit their extensive application in LIBs. Herein, a unique covalent organic framework (Tp-Azo-COF) with a dual active site of NN and CO is designed and successfully applied as the anode material for LIBs. Benefiting from its abundance of active sites, large conjugate structure, large surface area, and accessible Li + transport channels, the Tp-Azo-COF anode materials present high electrochemical kinetics and structural stability. The assembled LIBs deliver a specific capability of 305.97 mAh g −1 at a current density of 1000 mA g −1 after 3000 cycles. This work may inspire avenues for the development of advanced organic materials of inexpensive, sustainable, and durable rechargeable batteries.

Although many efforts have been devoted to the adsorptive removal of phosphate from aqueous solutions and eutrophic water, it is still highly desirable to develop novel adsorbents with high adsorption capacities. In this study, Fe-based metal-organic frameworks (MOFs), MIL-101 and NH2-MIL-101, are fabricated through a general facile strategy. Their performance as an adsorbent for phosphate removal is investigated. Experiments are performed to study the effects of various factors on the phosphate adsorption, including adsorbent dosage, contact time and co-existing ions. Both MIL-101(Fe) and NH2-MIL-101(Fe) show highly effective removal of phosphates from aqueous solutions, and the concentration of phosphates decrease sharply from the initial 0.60 mg·L−1 to 0.045 and 0.032 mg·L−1, respectively, within just 30 min of exposure. The adsorption kinetics and adsorption isotherms reveal that NH2-MIL-101(Fe) has higher adsorption capacity than MIL-101(Fe) possibly due to the amine group. Furthermore, the Fe-based MOFs also exhibit a high selectivity towards phosphate over other anions such as chloride, bromide, nitrate and sulfate. Particularly, the prepared Fe-based MIL-101 materials are also capable of adsorbing phosphate in an actual eutrophic water sample and display better removal effect.

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