Thermal Conversion of Core–Shell Metal–Organic Frameworks: A New Method for Selectively Functionalized Nanoporous Hybrid Carbon

Facile Synthesis of Au or Ag Nanoparticles-Embedded Hollow Carbon Microspheres from Metal-Organic Framework Hybrids and Their Efficient Catalytic Activities

Au or Ag nanoparticles-embedded hollow carbon spheres, which display outstanding catalytic activity and excellent recyclability, are prepared by a one-step pyrolysis of metal-organic framework (MOF) hybrids consisting of polystyrene cores and MOF shells loaded with noble metal ions (polystyrene@ZIF-8/M(n+) ; M(n+) = Au(3+) or Ag(+) ).

Surface-Plasmon-Enhanced Photodriven CO2 Reduction Catalyzed by Metal-Organic-Framework-Derived Iron Nanoparticles Encapsulated by Ultrathin Carbon Layers

Highly efficient utilization of solar light with an excellent reduction capacity is achieved for plasmonic Fe@C nanostructures. By carbon layer coating, the optimized catalyst exhibits enhanced selectivity and stability applied to the solar-driven reduction of CO2 into CO. The surface-plasmon effect of iron particles is proposed to excite CO2 molecules, and thereby facilitates the final reaction activity.

Nanoparticle Cookies Derived from Metal-Organic Frameworks: Controlled Synthesis and Application in Anode Materials for Lithium-Ion Batteries

The capacity of anode materials plays a critical role in the performance of lithium-ion batteries. Using the nanocrystals of oxygen-free metal-organic framework ZIF-67 as precursor, a one-step calcination approach toward the controlled synthesis of CoO nanoparticle cookies with excellent anodic performances is developed in this work. The CoO nanoparticle cookies feature highly porous structure composed of small CoO nanoparticles (≈12 nm in diameter) and nitrogen-rich graphitic carbon matrix (≈18 at% in nitrogen content). Benefiting from such unique structure, the CoO nanoparticle cookies are capable of delivering superior specific capacity and cycling stability (1383 mA h g(-1) after 200 runs at 100 mA g(-1) ) over those of CoO and graphite.

Phosphonate-Derived Nanoporous Metal Phosphates and Their Superior Energy Storage Application

Nanoporous nickel, aluminum, and zirconium phosphates (hereafter, abbreviated as NiP, AlP, and ZrP, respectively) with high surface areas and controlled morphology and crystallinity have been synthesized through simple calcination of the corresponding phosphonates. For the preparation of phosphonate materials, nitrilotris(methylene)triphosphonic acid (NMPA) is used as phosphorus source. The organic component in the phosphonate materials is thermally removed to form nanoporous structures in the final phosphate materials. The formation mechanism of nanoporous structures, as well as the effect of applied calcination temperatures on the morphology and crystallinity of the final phosphate materials, is carefully discussed. Especially, nanoporous NiP materials have a spherical morphology with a high surface area and can have great applicability as an electrode material for supercapacitors. It has been found that there is a critical effect of particle sizes, surface areas, and the crystallinities of NiP materials toward electrochemical behavior. Our nanoporous NiP material has superior specific capacitance, as compared to various phosphate nanomaterials reported previously. Excellent retention capacity of 97% is realized even after 1000 cycles, which can be ascribed to its high structural stability.

A Co₃O₄-embedded porous ZnO rhombic dodecahedron prepared using zeolitic imidazolate frameworks as precursors for CO₂ photoreduction

Metal-organic frameworks (MOFs) are attracting considerable attention for their use as both the precursor and the template to prepare metal oxides or carbon-based materials. For the first time in this paper, the core-shell ZIF-8@ZIF-67 crystals are thermally converted into porous ZnO@Co3O4 composites by combining a seed-mediated growth process with a two-step calcination. The designed porous ZnO@Co3O4 composites exhibited the highest photocatalytic activity with an excellent stability for the reduction of CO2 among the commonly reported composite photocatalysts. Their superior photocatalytic performance is demonstrated to be resulting from the unique porous structure of ZnO@Co3O4 and the co-catalytic function of Co3O4 which can effectively suppress the photocorrosion of ZnO.

Directed Growth of Metal-Organic Frameworks and Their Derived Carbon-Based Network for Efficient Electrocatalytic Oxygen Reduction

A honeycomb-like carbon-based network is obtained by in situ nucleation and directed growth of metal-organic framework (MOF) arrays on the surface of layered double hydroxide (LDH) nanoplatelets, followed by a subsequent pyrolysis process, which exhibits largely enhanced electrocatalytic ORR performances. A successful paradigm for the directed growth of highly oriented MOF arrays is demonstrated, with potential applications for energy storage and conversion.

Magnetic Metal-Organic Frameworks for Efficient Carbon Dioxide Capture and Remote Trigger Release

Magnetic metal-organic framework (MOF) composites show highly efficient CO2 desorption capacities upon their exposure to an alternating magnetic field, demonstrating a magnetic induction swing strategy for potentially low-energy regeneration of MOF adsorbents.

Cage-Type Highly Graphitic Porous Carbon-Co3O4 Polyhedron as the Cathode of Lithium-Oxygen Batteries

A novel cage-type highly graphitic porous carbon-Co3O4 (GPC-Co3O4) polyhedron was designed and successfully prepared for the first time by executing a two-step annealing of core-shell structured metal-organic frameworks (MOFs). The low graphitic carbon cores were selectively removed during the secondary annealing in air atmospheres, leaving the interior voids due to their lower thermal stability compared with the graphitic carbon shells. Inspired by the unique properties of the cage-type GPC-Co3O4 polyhedron, GPC-Co3O4 was assembled as an oxygen electrode for a rechargeable Li-O2 battery without the additional conductive agent. The efficient generation of Li2O2 during discharging and the reversible decomposition of Li2O2 during charging were clearly observed by XRD patterns and SEM images. The GPC-Co3O4 polyhedron integrates the beneficial properties, including high electronic conductivity, the rigid cage-type structure consisting of the mesoporous walls and interior void space, as well as the uniformly embedded catalytically active Co3O4 nanoparticles. As a result, the GPC-Co3O4 cathode displays a low charge overpotential of 0.58 V, a good rate capability, and a long cycle life in a Li-O2 battery.

CeO2 nanowires self-inserted into porous Co3O4 frameworks as high-performance "noble metal free" hetero-catalysts

Recently, mixed metal oxides have attracted tremendous interest because of their great importance for fundamental studies and practical applications in the catalytic field to replace expensive noble metals. Herein, we report the designed synthesis of novel CeO2-Co3O4 mixed metal oxides with complex nanostructures using uniform short CeO2 nanowires self-inserted into ZIF-67 nanocrystals as precursors followed by a thermal annealing treatment. Interestingly, such a synthetic strategy can be easily extended to fabricate other CeO2 nanowires inserted into metal oxide nanoframeworks such as NiCo2O4 and ZnCo2O4. Choosing the NO reduction reaction by CO as the catalytic model, the as-obtained CeO2-Co3O4 hybrids exhibited enhanced catalytic performance, which could be attributed to the strong two-phase interaction between each component.

Active Sites Implanted Carbon Cages in Core-Shell Architecture: Highly Active and Durable Electrocatalyst for Hydrogen Evolution Reaction

Low efficiency and poor stability are two major challenges we encounter in the exploration of non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) in both acidic and alkaline environment. Herein, the hybrid of cobalt encapsulated by N, B codoped ultrathin carbon cages (Co@BCN) is first introduced as a highly active and durable nonprecious metal electrocatalysts for HER, which is constructed by a bottom-up approach using metal organic frameworks (MOFs) as precursor and self-sacrificing template. The optimized catalyst exhibited remarkable electrocatalytic performance for hydrogen production from both both acidic and alkaline media. Stability investigation reveals the overcoating of carbon cages can effectively avoid the corrosion and oxidation of the catalyst under extreme acidic and alkaline environment. Electrochemical active surface area (EASA) evaluation and density functional theory (DFT) calculations revealed that the synergetic effect between the encapsulated cobalt nanoparticle and the N, B codoped carbon shell played the fundamental role in the superior HER catalytic performance.

Constructing nitrogen-doped nanoporous carbon/graphene networks as promising electrode materials for supercapacitive energy storage

Nitrogen-doped nanoporous carbon/graphene networks have been constructed and show a larger specific capacitance than that of NPCs and rGO.

Magnetic nanoporous hybrid carbon from core–shell metal–organic frameworks for glycan extraction

Magnetic nanoporous carbon (NPC) materials, which can be thoroughly separated from an aqueous solution easily, are very promising adsorbents.

Zeolitic imidazolate framework (ZIF-8) derived nanoporous carbon: the effect of carbonization temperature on the supercapacitor performance in an aqueous electrolyte

Nanoporous carbons prepared at various carbonization temperatures are tested using an aqueous electrolyte for supercapacitor applications.

An unprecedented single platform via cross-linking of zeolite and MOFs

The unprecedented ternary nanocomposites have been synthesized as a single platform via cross-linking of two nanoporous materials, MOFs and Pt nanoparticle (NP) loaded zeolite.

Well-defined gold nanoparticle@N-doped porous carbon prepared from metal nanoparticle@metal–organic frameworks for electrochemical sensing of hydrazine

Schematic diagram of the preparation of Au@NPC and its application to the determination of hydrazine.

Nanoscale iron carboxylate metal organic frameworks as drug carriers for magnetically aided intracellular delivery

We report the synthesis, characterisation, and magnetically controlled drug delivery applications of drug-encapsulated iron carboxylate nanoscale metal organic frameworks (NMOFs).

Novel nanoporous carbon derived from metal–organic frameworks with tunable electromagnetic wave absorption capabilities

Core–shell ZIF-8@ZIF-67 crystals, which integrate the properties of single ZIF-8 and ZIF-67, are elaborately designed for the first time by applying a seed-mediated growth technique.

Co3O4/ZnO nanoheterostructure derived from core–shell ZIF-8@ZIF-67 for supercapacitors

Co₃O₄/ZnO heteronanostructures were prepared through the thermal conversion of core–shell ZIF-8@ZIF-67, exhibiting a high specific capacitance and improved rate capability.

Nitrogen-doped hollow carbon spheres with large mesoporous shells engineered from diblock copolymer micelles

Nitrogen-doped hollow carbon spheres with engineered large tunable mesoporous (∼20 nm) shells are successfully synthesized for the first time by using a dual-template method.

A high-performance supercapacitor cell based on ZIF-8-derived nanoporous carbon using an organic electrolyte

Low-cost supercapacitors have the ability to rapidly store a large amount of charge, which makes them the best alternative to batteries in portable electronics.

A noble and single source precursor for the synthesis of metal-rich sulphides embedded in an N-doped carbon framework for highly active OER electrocatalysts

Metal-rich sulphide (Co₉S₈ and Ni₃S₂) embedded in N-doped carbon (NC) frameworks were synthesized from novel Tris(ethylenediamine) Metal (ii) Sulfate complex whereas counter sulphate (SO₄²⁻) ion is the source of S. Both the hybrids show superior OER activity compared to commercial RuO₂.

Guidance from an in situ hot stage in TEM to synthesize magnetic metal nanoparticles from a MOF

The transition from Ni-MOF to Ni-NPC was first observed using TEM combined with an in situ hot stage.

From an equilibrium based MOF adsorbent to a kinetic selective carbon molecular sieve for paraffin/iso-paraffin separation

For the first time, a carbon molecular sieve was obtainedviacarbonization of a metal–organic framework, exhibiting excellent performance in paraffin/iso-paraffin separation.

Formation of large nanodomains in liquid solutions near the phase boundary

Large nanodomains were formed in liquid solutions near the phase separation point where the size of nanodomains increased dramatically.

Interlocked multi-armed carbon for stable oxygen reduction

N-Doped multi-armed carbon with an interlocked structure shows high oxygen reduction activity and resistance to methanol crossover effects.

Towards rational design of core–shell catalytic nanoreactor with high performance catalytic hydrogenation of levulinic acid

Core–shell catalytic nanoreactor was designed, exhibiting high catalytic activity for levulinic acid hydrogenation.

Mesoporous Co3O4@carbon composites derived from microporous cobalt-based porous coordination polymers for enhanced electrochemical properties in supercapacitors

In this work, mesoporous Co₃O₄@carbon composites were prepared through a simple, one-step, carbonization of microporous cobalt-based porous coordination polymer ZSA-1.

Cobalt nanoparticle-embedded carbon nanotube/porous carbon hybrid derived from MOF-encapsulated Co3O4 for oxygen electrocatalysis

A MOF encapsulated Co₃O₄-derived Co–carbon nanotube/porous carbon electrocatalyst exhibits highly efficient electrocatalytic activity for the ORR and OER.

Formation of hollow and mesoporous structures in single-crystalline microcrystals of metal-organic frameworks via double-solvent mediated overgrowth

The creation of hierarchical porosity in metal-organic frameworks (MOFs) could benefit various applications of MOFs such as gas storage and separation. Having single-crystalline microcrystals instead of poly-crystalline composites is critical for these potential applications of MOFs with hierarchical porosity. We developed a room temperature synthetic method to generate uniform hollow and mesoporous zeolitic imidazolate framework-8 (ZIF-8) microcrystals with a single-crystalline structure via overgrowing a ZIF-8 shell in methanol solution on a ZIF-8 core with water adsorbed in the pores. The cavities formed as a result of the different solvent micro-environment. This double-solvent mediated overgrowth method could be applied to prepare other MOFs with hierarchical porosity.

Post-Synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals

Controlling the shape of metal-organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post-synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet-chemistry process at room temperature to control the anisotropic etching of colloidal ZIF-8 and ZIF-67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid-base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal-ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution.

3D architecture constructed via the confined growth of MoS2 nanosheets in nanoporous carbon derived from metal-organic frameworks for efficient hydrogen production

The design and synthesis of robust, high-performance and low-cost three-dimensional (3D) hierarchical structured materials for the electrochemical reduction of water to generate hydrogen is of great significance for practical water splitting applications. In this study, we develop an in situ space-confined method to synthesize an MoS2-based 3D hierarchical structure, in which the MoS2 nanosheets grow in the confined nanopores of metal-organic frameworks (MOFs)-derived 3D carbons as electrocatalysts for efficient hydrogen production. Benefiting from its unique structure, which has more exposed active sites and enhanced conductivity, the as-prepared MoS2/3D nanoporous carbon (3D-NPC) composite exhibits remarkable electrocatalytic activity for the hydrogen evolution reaction (HER) with a small onset overpotential of ∼0.16 V, large cathodic currents, small Tafel slope of 51 mV per decade and good durability. We anticipate that this in situ confined growth provides new insights into the construction of high performance catalysts for energy storage and conversion.

Mesoporous Transition Metal Oxides for Supercapacitors

Recently, transition metal oxides, such as ruthenium oxide (RuO₂), manganese dioxide (MnO₂), nickel oxides (NiO) and cobalt oxide (Co₃O₄), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO₂, MnO₂, NiO, Co₃O₄ and nickel cobaltite (NiCo₂O₄), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors.

Three-Dimensional Nitrogen-Doped Hierarchical Porous Carbon as an Electrode for High-Performance Supercapacitors

A facile and sustainable procedure for the synthesis of nitrogen-doped hierarchical porous carbons with a three-dimensional interconnected framework (NHPC-3D) was developed. The strategy, based on a colloidal crystal-templating method, utilizes nitrogenous dopamine as the precursor due to its unique properties, including self-polymerization under mild alkaline conditions, coating onto various surfaces, a high carbonization yield, and well-preserved nitrogen doping after heat treatment. The obtained NHPC-3D possesses a high surface area of 1056 m(2)  g(-1) , a large pore volume of 2.56 cm(3)  g(-1) , and a high nitrogen content of 8.2 wt %. The NHPC-3D is implemented as the electrode material of a supercapacitor and exhibits a specific capacitance as high as 252 F g(-1) at a current density of 2 A g(-1) . The device also shows a high capacitance retention of 75.7 % at a higher current density of 20 A g(-1) in aqueous electrolyte due to a sufficient surface area for charge accommodation, reversible pseudocapacitance, and minimized ion-transport resistance, as a result of the advantageous interconnected hierarchical porous texture. These results showcase NHPC-3D as a promising candidate for electrode materials in supercapacitors.