Development of new porous materials as hosts to suppress the dissolution and shuttle of lithium polysulfides is beneficial for constructing highly efficient lithium–sulfur batteries (LSBs). Although 2D covalent organic frameworks (COFs) as host materials exhibit promising potential for LSBs, their performance is still not satisfactory. Herein, we develop polyimide COFs (PI-COF) with a well-defined lamellar structure, which can be exfoliated into ultrathin (∼1.2 nm) 2D polyimide nanosheets (PI-CONs) with a large size (∼6 μm) and large quantity (40 mg/batch). Explored as new sulfur host materials for LSBs, PI-COF and PI-CONs deliver high capacities (1330 and 1205 mA h g–1 at 0.1 C, respectively), excellent rate capabilities (620 and 503 mA h g–1 at 4 C, respectively), and superior cycling stability (96% capacity retention at 0.2 C for PI-CONs) by virtue of the synergy of robust conjugated porous frameworks and strong oxygen–lithium interactions, surpassing the vast majority of organic/polymeric lithium–sulfur battery cathodes ever reported. Our finding demonstrates that ultrathin 2D COF nanosheets with carbonyl groups could be promising host materials for LSBs with excellent electrochemical performance.

Metal clusters exhibit diverse structures, emerging functions, and applications; thus, incorporating clusters into metal-organic frameworks (MOFs) brings tremendous merits. Although the construction of cluster-based MOFs is sophisticated, the reticular materials constructed from a combination of the chemistry of metal clusters and covalent organic frameworks (COFs) remain unexplored. Herein, we prepared two Cu(I) cluster-based MOFs with cyclic trinuclear units (CTUs), termed JNM-1 and JNM-2, either by a stepwise synthetic approach or by a one-pot reaction, for networking clusters with dynamic covalent chemistry, rarely utilized in MOF synthesis. The generated JNMs exhibited excellent stability and could be used as recyclable catalysts for palladium-free Sonogashira coupling reactions with high efficiency and tolerance (>90% yield for nine examples), without loss of performance for at least five cycle runs. In addition, conjugated single molecular wires with lengths ranging from 1.6 to 2.7 nm were synthesized feasibly using the JNM-1 catalyst.

The interlay sliding of 2D metal- and covalent-organic frameworks (MOFs and COFs) affects not only the layout feature of the structures but also the functional output of the materials. However,...

The design of adsorbents for rapid, selective extraction of ultra-trace amounts of gold from complex liquids is desirable from both an environmental and economical point of view. However, the development of such materials remains challenging. Herein, we report the fabrication of two vinylene-linked two-dimensional silver(I)-organic frameworks prepared via Knoevenagel condensation. This material enables selective sensing of gold with a low limit of detection of 60 ppb, as well as selective uptake of ultra-trace gold from complex aqueous mixtures including distilled water with 15 competing metal ions, leaching solution of electronic waste (e-waste), wastewater, and seawater. The present adsorbent delivers a gold adsorption capacity of 954 mg g−1, excellent selectivity and reusability, and can rapidly and selectively extract ultra-trace gold from seawater down to ~20 ppb (94% removal in 10 minutes). In addition, the purity of recovered gold from e-waste reaches 23.8 Karat (99.17% pure).