Iron sulfide-embedded carbon microspheres were prepared via a solvothermal process and show high specific capacity and excellent high-rate performance as anode material for lithium-ion batteries.

Membranes of sub‐2‐nanometer channels show high ion transport rates, but it remains a great challenge to design such membranes with desirable ion selectivities for ion separation applications. Here, covalent organic framework (COF) membranes with a channel size of ≈1.4 nm and abundant hydrogen bonding sites, exhibiting efficient ion sieving properties are demonstrated. The COF membranes have high monovalent cation permeation rates of 0.1–0.2 mol m−2 h−1 and extremely low multivalent cation permeabilities, leading to high monovalent over divalent ion selectivities for K+/Mg2+ of ≈765, Na+/Mg2+ of ≈680, and Li+/Mg2+ of ≈217. Experimental measurements and theoretical simulations reveal that the hydrogen bonding interaction between hydrated cations and the COF channel wall governs the high selectivity, and divalent cations transport through the channel needs to overcome higher energy barriers than monovalent cations. These findings provide an effective strategy for developing sub‐2‐nanometer sized membranes with specific interaction sites for high‐efficiency ionic separation.

Novel hierarchical porous carbon nanosheets (HPCS) with quantities of micropores and mesopores were prepared on a large-scale by using thermoplastic phenolic formaldehyde resin as the carbon source and copper nitrate as the template precursor. The HPCS, possessing a thickness of about 40 nm and the width of several microns, exhibited a high specific capacity and favorable high-rate performance when used as an anode material for lithium ion batteries (LIBs). The reversible capacities were 748 mA h g À1 at a current density of 20 mA g À1 and 460 mA h g À1 even at 1 A g À1 , which were much higher than those of traditional porous carbon materials. It also showed superior cyclical stability for only 0.3% capacity loss per cycle under high rate charge-discharge process, suggesting that HPCS should be a promising candidate for anode materials in high-rate LIBs. The roles of various-sized pores in HPCS in Li storage were discussed briefly.

HIGHLIGHTS • Ultrathin (< 600 nm) and defect-free leaf-like UiO-66-SO 3 H membranes were fabricated via in situ smart growth. • The sulfonated angstrom-sized ion transport channels in the membranes could accelerate the cation permeation (~ 3× faster than nonfunctionalized UiO-66 membrane) and achieve a high ion selectivity (Na + /Mg 2+ > 140). ABSTRACT Metal-organic frameworks (MOFs) with angstrom-sized pores are promising functional nanomaterials for the fabrication of cation permselective membranes (MOF-CPMs). However, only a few research reports show successful preparation of the MOF-CPMs with good cation separation performance due to several inherent problems in MOFs, such as arduous selfassembly, poor water resistance, and tedious fabrication strategies. Besides, low cation permeation flux due to the absence of the cation permeation assisting functionalities in MOFs is another big issue, which limits their widespread use in membrane technology. Therefore, it is necessary to fabricate functional MOF-CPMs using simplistic strategies to improve cation permeation. In this context, we report a facile in situ smart growth strategy to successfully produce ultrathin (< 600 nm) and leaflike UiO-66-SO 3 H membranes at the surface of anodic alumina oxide. The physicochemical characterizations confirm that sulfonated angstrom-sized ion transport channels exist in the as-prepared UiO-66-SO 3 H membranes, which accelerate the cation permeation (~ 3× faster than non-functionalized UiO-66 membrane) and achieve a high ion selectivity (Na + /Mg 2+ > 140). The outstanding cation separation performance validates the importance of introducing sulfonic acid groups in MOF-CPMs.

Membranes of high ion permselectivity are significant for the separation of ion species at the subnanometer scale. Here, we report porous organic cage (i.e., CC3) membranes with hierarchical channels including discrete internal cavities and cage-aligned external cavities connected by subnanometer-sized windows. The windows of CC3 sieve monovalent ions from divalent ones and the dual nanometer-sized cavities provide pathways for fast ion transport with a flux of 1.0 mol m–2 h–1 and a mono-/divalent ion selectivity (e.g., K+/Mg2+) up to 103, several orders of magnitude higher than the permselectivities of reported membranes. Molecular dynamics simulations illustrate the ion transport trajectory from the external to internal cavity via the CC3 window, where ions migrate in diverse hydration states following the energy barrier sequence of K+ < Na+ < Li+ ≪ Mg2+. This work sheds light on ion transport properties in porous organic cage channels of discrete frameworks and offers guidelines for developing membranes with hierarchical channels for efficient ion separation.