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Fabrication of single-crystalline metal-organic framework (MOF) hollow nanostructures with two-dimensional (2D) morphologies is a challenging task. Herein, twin-like MOF nanobricks, a quasi-hollow 2D architecture, with multi-metal nodes and replaceable organic ligands, are uniformly and firmly grown on conductive Ni foam through a generic one-pot approach. The formation process of twin-like MOF nanobricks mainly includes selective epitaxial growth of Fe-rich MOF layer and simultaneously dissolution of the pre-formed Ni-rich metal-organic frameworks (MOFs), all of which can be ascribed to a special self-templated mechanism. The fantastic structural merits of twin-like MOF nanobrick arrays, featuring highly exposed active sites, remarkable electrical conductivity, and hierarchical porosities, enable this material for efficient electrocatalysis. Using bimetallic NiFe-MOFs grown on Ni foam as an example, the resultant twin-like nanobrick arrays can be directly utilized as three-dimensional (3D) integrated electrode for high-performance water oxidation in 1 M KOH with a low overpotential, fast reaction kinetics (28.5 mV·dec−1), and superb stability. Interestingly, the unstable NiFe-MOFs were served as an oxygen evolution reaction (OER) pre-catalyst and the single-crystalline NiFe-MOF precursor can be in-situ topochemically regulated into porous and low-crystalline NiFeOx nanosheets during the OER process. This work extends the hollowing strategy to fabricate hollow MOFs with 2D architectures and highlights their direct utilization for advanced electrocatalysis.

The cruciform linker molecule here features two designer functions: the pyrazole donors for framework construction, and the vicinal alkynyl units for benzannulation to form nanographene units into the Ni8-pyrazolate scaffold. Unlike the full 12 connections of the Ni8(OH)4(H2O)2 clusters in other Ni8-pyrazolate networks, significant linker deficiency was observed here, leaving about half of the Ni(II) sites capped by acetate ligands, which can be potentially removed to open the metal sites for reactivity. The crystalline Ni8-pyrazolate scaffold also retains the crystalline order even after thermal treatments (up to 300 °C) that served to partially graphitize the neighboring alkyne units. The resultant nanographene components enhance the electroactive properties of the porous hosts, achieving hydrogen evolution reaction (HER) activity that rivals that of topical nickel/palladium-enabled materials.

A novel 2D porous Zr(IV)-based metal-organic framework (USTS-7) was assembled from 2,5-bis[2-(methylthio)ethylthio]terephthalic acid and ZrCl4. USTS-7 retains its stability in water, strong acid, and base; moreover, it is highly luminescent and displays a remarkable selective sensing property toward Cr2O72- in aqueous solution with a very low detection limit.

Despite the notable progress in perovskite solar cells, maintaining long-term operational stability and minimizing potentially leaked lead (Pb2+) ions are two challenges that are yet to be resolved. Here we address these issues using a thiol-functionalized 2D conjugated metal–organic framework as an electron-extraction layer at the perovskite/cathode interface. The resultant devices exhibit high power conversion efficiency (22.02%) along with a substantially improved long-term operational stability. The perovskite solar cell modified with a metal–organic framework could retain more than 90% of its initial efficiency under accelerated testing conditions, that is continuous light irradiation at maximum power point tracking for 1,000 h at 85 °C. More importantly, the functionalized metal–organic framework could capture most of the Pb2+ leaked from the degraded perovskite solar cells by forming water-insoluble solids. Therefore, this method that simultaneously tackles the operational stability and lead contamination issues in perovskite solar cells could greatly improve the feasibility of large-scale deployment of perovskite photovoltaic technology. Two-dimensional conjugated metal–organic frameworks used as an electron-extraction layer enable the realization of highly stable perovskite solar cells with minimized lead ion leakage.

We employ facile aromatic nucleophilic substitution between the mercapto (-SH) and arylfluoro (Ar-F) groups to achieve extensive and robust cross-linking of a coordination host by porphyrin guests that also serve the purpose of versatile postsynthetic functionalization. For this, a tritopic linker with three trident-like thiol-flanked carboxyl units are reacted with ZrOCl

Nanoporous gold (NPG), whose chemical and physical properties largely depend on its ligament size and pore size, is attractive for many applications. However, it is difficult to achieve NPG with ul...

Finely dispersed Co(0) and CoO species were efficiently loaded into a stable metal–organic framework to impart catalytic activities to the porous solid. The metalation of the MOF host is facilitate...

A stable porous sorbent M1 was achieved through the specific transformation of flexible thioalkyl groups and metal cluster sites in a zirconium MOF (metal–organic framework; Zr-L) template. The target polymer combines sulfoxide/sulfone and phosphoric acid in a single framework, which was fully characterized by 1H-NMR, PXRD, IR, and elemental analysis. When employed as the heavy metal adsorbent, M1 exhibit a remarkable Eu­(III) sorption behavior, achieving both high chemical affinity (Kd = 105) and sorption capacity (the maximum Eu­(III) sorption capacity reached 220 mg g–1 at pH = 4.0 and T = 298 K calculated from the Langmuir model). Recyclability and selectivity test of M1 further prove that the sorbent is highly stable and effective for europium enrichment in the aqueous solution. This work takes focus on the introduction of multifunctional groups into a single polymeric framework in a feasible and environmentally friendly way and highlights the sorption efficiency for europium removal from the aqueous solution.

Crystalline coordination architectures with coordinatively unsaturated metal sites are of great importance for their attractive properties. Tunable side chains of the 4-formylimidazole here were employed for directing the subcomponent self-assembly of (CuIIN4)2(CuII)2 (1), {(CuIIN4)(CuII)2}n (2), {L(CuII)2}n (3) under the same solvothermal condition, giving the structural diversity. The unique square-planar CuII/NiIIN4 units with open metal sites can not only be in situ embedded in 1 and 2, but also be successfully immobilized in {(NiIIN4)2(CuICN)9}n (4) and {(CuIIN4)2(CuICN)9}n (5), through the metalloligand strategy. Enzyme-like substrate-specific activity was observed by employing 5 as a heterogeneous catalyst, which exhibit increased activity and high selectivity towards the catalytic oxidation of 1-phenylethyl alcohol derivatives. This work presents two promising methodologies for the introduction of controllable open metal sites in versatile crystalline coordination complexes and their application i...

Donor–acceptor two-dimensional covalent organic frameworks, PD-COF-23 and PD-COF-23-Ni, are constructed and applied for selective CO2 reduction with CO conversion rates of 20.9 μmol g−1 h−1 and 40.0 μmol g−1 h−1, respectively, in the absence of any additional photosensitizers and noble metal co-catalysts within an operation time of 25 h. The multilayer nanosheet structure, efficient charge separation and transport, and internal reductive quenching cycle of the NiTAPP fragments of PD-COF-23-Ni result in its higher photocatalytic efficiency than that of PD-COF-23.

Thiol groups (−SH) offer versatile reactivity for functionalizing metal–organic frameworks, and yet thiol-equipped MOF solids remain underexplored due to synthetic challenges. Building on the recent breakthrough using benzyl mercaptan as the sulfur source and AlCl3 for uncovering the thiol function, we report on the thiol-equipped linker 3,3′-dimercaptobiphenyl-4,4′-dicarboxylic acid and its reaction with Zr(IV) ions to form a UiO-67-type MOF solid with distinct functionalities. The thiol-equipped UiO-67 scaffold shows substantial stability toward oxidation, e.g., it can be treated with 30% H2O2 to afford oxidation of the thiol to the strongly acidic sulfonic function while maintaining the ordered porous MOF structure. The thiol groups also effectively take up palladium(II) ions from solutions to allow for comparative studies on catalytic activities and to help elucidate how the spatial configuration of the thiol groups can be engineered to impact the performance of heterogeneous catalysis in the solid st...

The cruciform linker molecule here features two designer functions: the pyrazole donors for framework construction, and the vicinal alkynyl units for benzannulation to form nanographene units into the Ni

A novel 2D porous Zr(IV)-based metal-organic framework (USTS-7) was assembled from 2,5-bis[2-(methylthio)ethylthio]terephthalic acid and ZrCl

Donor-acceptor two-dimensional covalent organic frameworks, PD-COF-23 and PD-COF-23-Ni, are constructed and applied for selective CO2 reduction with CO conversion rates of 20.9 μmol g-1 h-1 and 40.0 μmol g-1 h-1, respectively, in the absence of any additional photosensitizers and noble metal co-catalysts within an operation time of 25 h. The multilayer nanosheet structure, efficient charge separation and transport, and internal reductive quenching cycle of the NiTAPP fragments of PD-COF-23-Ni result in its higher photocatalytic efficiency than that of PD-COF-23.

The cruciform linker molecule here features two designer functions: the pyrazole donors for framework construction, and the vicinal alkynyl units for benzannulation to form nanographene units into the Ni8-pyrazolate scaffold. Unlike the full 12 connections of the Ni8(OH)4(H2O)2 clusters in other Ni8-pyrazolate networks, significant linker deficiency was observed here, leaving about half of the Ni(II) sites capped by acetate ligands, which can be potentially removed to open the metal sites for reactivity. The crystalline Ni8-pyrazolate scaffold also retains the crystalline order even after thermal treatments (up to 300 °C) that served to partially graphitizes the neighboring alkyne units. The resultant nanographene components enhance the electroactive properties of the porous hosts, achieving hydrogen evolution reaction (HER) activity that rivals topical nickel/palladium-enabled materials.

The series of highly stable porous solids here feature systematic, regiospecific sulfur substitutions on the organic linkers for versatile functions. One major surprise lies in the controllable sequential reactions between sodium thiomethoxide (NaSMe) and octafluorobiphenyl-4,4'-dicarboxylic acid (H

Finely dispersed Co(0) and CoO species were efficiently loaded into a stable metal-organic framework to impart catalytic activities to the porous solid. The metalation of the MOF host is facilitated by the dense arrays of accessible alkyne units that boost the alkyne-Co

Breaking the cycle of silver pyrazolates: instead of the common loops (e.g., the Ag3N6 ring), we report an infinite array in which the equispaced Ag(I) ions form a zigzag chain, with the associated anthracene bis(pyrazolate) linkers cofacially aligned one to another. In addition to the strong Ag(I)–N bonds and the distinct argentophilic interactions, the Ag(I) ions also form interlayer, metal−π contacts with the anthracene cores. The resultant two-dimensional network exhibits significant electronic interaction between the Ag(I) centers and the large aromatic linker molecule, as revealed by the red shift of photoemission spectra and the significant reduction of the electronic band edge as determined by diffuse reflectance spectroscopy. The solid sample is stable in air and water.

We employ a two-step strategy for accessing crystalline porous covalent networks of highly conjugated π-electron systems. For this, we first assembled a crystalline metal-organic framework (MOF) precursor based on Zr(IV) ions and a linear dicarboxyl linker molecule featuring backfolded, highly unsaturated alkyne backbones; massive thermocyclization of the organic linkers was then triggered to install highly conjugated, fused-aromatic bridges throughout the MOF scaffold while preserving the crystalline order. The formation of cyclized carbon links not only greatly strengthen the precursor coordination scaffold, but more importantly, enhance electroactivity and charge transport throughout the polycyclic aromatic grid.