Developing conjugated three-dimensional (3D) covalent organic frameworks (COFs) still remains an extremely difficult task due to the lack of enough conjugated 3D building blocks. Herein, condensation between an 8-connected pentiptycene-based D 2h building block (DMOPTP) and 4-connected square-planar linkers affords two 3D COFs (named 3D-scu-COF-1 and 3D-scu-COF-2). A combination of the 3D homoaromatic conjugated structure of the former building block with the 2D conjugated structure of the latter linking units enables the π-electron delocalization over the whole frameworks of both COFs, endowing them with excellent conductivities of 3.2−3.5 × 10 −5 S cm −1 . In particular, the 3D rigid quadrangular prism shape of DMOPTP guides the formation of a twofold interpenetrated scu 3D topology and high-connected permanent porosity with a large Brunauer−Emmett−Teller (BET) surface area of 2340 and 1602 m 2 g −1 for 3D-scu-COF-1 and 3D-scu-COF-2, respectively, ensuring effective small molecule storage and mass transport characteristics. This, in combination with their good charge transport properties, renders them promising sulfur host materials for lithium−sulfur batteries (LSBs) with high capacities (1035−1155 mA h g −1 at 0.2 C, 1 C = 1675 mA g −1 ), excellent rate capabilities (713−757 mA h g −1 at 5.0 C), and superior cycling stability (71−83% capacity retention at 2.0 C after 500 cycles), surpassing the most of organic LSB cathodes reported thus far.

Lithium-sulfur batteries (LSBs) have been considered as a promising candidate for next-generation energy storage devices, which however still suffer from the shuttle effect of the intermediate lithium polysulfides (LiPSs). Covalent-organic frameworks (COFs) have exhibited great potential as sulfur hosts for LSBs to solve such a problem. Herein, a pentiptycene-based D 2h symmetrical octatopic polyaldehyde, 6,13-dimethoxy-2,3,9,10,18,19,24,25-octa(4′-formylphenyl)pentiptycene (DMOPTP), was prepared and utilized as a building block toward preparing COFs. Condensation of DMOPTP with 4-connected tetrakis(4-aminophenyl)methane affords an expanded [8 + 4] connected network 3D-flu-COF, with a flu topology. The non-interpenetrated nature of the flu topology endows 3D-flu-COF with a high Brunauer–Emmett–Teller surface area of 2860 m2 g–1, large octahedral cavities, and cross-linked tunnels in the framework, enabling a high loading capacity of sulfur (∼70 wt %), strong LiPS adsorption capability, and facile ion diffusion. Remarkably, when used as a sulfur host for LSBs, 3D-flu-COF delivers a high capacity of 1249 mA h g–1 at 0.2 C (1.0 C = 1675 mA g–1), outstanding rate capability (764 mA h g–1 at 5.0 C), and excellent stability, representing one of the best results among the thus far reported COF-based sulfur host materials for LSBs and being competitive with the state-of-the-art inorganic host materials.

The visible-light-driven photocatalytic reduction reaction of carbon dioxide (CO 2 ) (CO 2 RR) to value-added fuels presents a feasible approach to curb anthropogenic CO 2 emissions and mitigate the increasing energy crisis. However, developing photocatalysts with excellent performance still remains a great challenge in this field. Herein Co,Cu,N-codoped carbon nanoparticles (Co 1 Cu 1 /NC) were fabricated through the pyrolysis of zeolitic imidazolate framework (ZIF-8) with Cu(NO 3 ) 2 adsorbed inside the cavities and CoTBPP decorated over the surface of ZIF. Spherical aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and electron energy loss spectroscopy measurements disclose the dual-metal single-atomic nature of Co 1 Cu 1 /NC consisting of atomically dispersed Co−Cu pair sites on a nitrogen-doped carbon support. Extended X-ray absorption fine-structure analysis reveals the tetra-N-coordinated nature of each metal in Co 1 Cu 1 /NC (N 2 −Co−N 2 −Cu−N 2 ). For the purpose of comparative study, Co,N-and Cu,N-codoped carbon nanoparticles (Co 1 /NC and Cu 1 /NC) also with single atomic site nature have been fabricated following the same route. The as-prepared Co 1 Cu 1 /NC exhibits highly effective photocatalytic CO 2 -to-CO reduction with a considerably high CO-generating yield of 22.46 mmol g −1 and a CO selectivity of 83.4% after 2 h of visible-light irradiation. Experimental characterizations and in particular theoretical calculations disclose the close association of the remarkable CO 2 RR catalytic activity of Co 1 Cu 1 /NC with the synergetic effect of the Co−Cu atomic-pair sites, which facilitate the conversion of CO 2 to CO via lowering the energy barrier for the formation of the *COOH intermediate. This work paves a new avenue for the rational design and construction of atomic-pair photocatalysts with boosted performance.

Utilization of rigid, highly connected organic linkers is critical for the reticular synthesis of functional metal–organic frameworks (MOFs). However, highly‐stable MOFs (e.g. Al/Cr/Zr‐based MOFs) based on rigid ligands with more than 6 coordinating functions have been rarely achieved thus far. Herein, we describe the construction of two bcu Zr‐based MOFs (named ZrMOF‐1 and ZrMOF‐2) from peripherally extended pentiptycene ligands (H8PEP‐1 and H8PEP‐2) with rigid quadrangular prism shape possessing 8 carboxylic groups at the prism vertices. Particularly, ZrMOF‐1 exhibits microporous structure with large Bruno‐Emmett‐Teller surface area and high water stability, endowing it a promising water harvesting material with a high water uptake capacity of 0.83 gH2O gMOF−1 at P/P0=0.90 and 25 °C, a steep uptake at a low P/P0 of 0.30, and excellent durability over 500 water adsorption‐desorption cycles. Moreover, self‐consistent charge density functional tight‐binding calculations were carried out, rationalizing the water adsorbing process and amount in ZrMOF‐1.

Utilization of rigid, highly connected organic linkers is critical for the reticular synthesis of functional metal-organic frameworks (MOFs). However, highlystable MOFs (e.g. Al/Cr/Zr-based MOFs) based on rigid ligands with more than 6 coordinating functions have been rarely achieved thus far. Herein, we describe the construction of two bcu Zr-based MOFs (named ZrMOF-1 and ZrMOF-2) from peripherally extended pentiptycene ligands (H 8 PEP-1 and H 8 PEP-2) with rigid quadrangular prism shape possessing 8 carboxylic groups at the prism vertices. Particularly, ZrMOF-1 exhibits microporous structure with large Bruno-Emmett-Teller surface area and high water stability, endowing it a promising water harvesting material with a high water uptake capacity of 0.83 g H2O g MOF À 1 at P/P 0 = 0.90 and 25 °C, a steep uptake at a low P/P 0 of 0.30, and excellent durability over 500 water adsorption-desorption cycles. Moreover, self-consistent charge density functional tight-binding calculations were carried out, rationalizing the water adsorbing process and amount in ZrMOF-1.