"Hard" Emulsion-Induced Interface Super-Assembly: A General Strategy for Two-Dimensional Hierarchically Porous Metal-Organic Framework Nanoarchitectures.

Two-dimensional (2D) hierarchically porous metal-organic framework (MOF) nanoarchitectures with tailorable meso-/macropores hold great promise for enhancing mass transfer kinetics, augmenting accessible active sites, and thereby boosting performance in heterogeneous catalysis. However, achieving the general synthesis of 2D free-standing MOF nanosheets with controllable hierarchical porosity and thickness remains a challenging task. Herein, we present an ingenious "hard" emulsion-induced interface super-assembly strategy for preparing 2D hierarchically porous UiO-66-NH2 nanosheets with highly accessible pore channels, tunable meso-/macropore sizes, and adjustable thicknesses. The methodology relies on transforming the geometric shape of oil droplet templates within appropriate oil-in-water emulsions from conventional zero-dimensional (0D) "soft" liquid spheres to 2D "hard" solid sheets below the oil's melting/freezing point. Subsequent surfactant exchange on the surface of 2D "hard" emulsions facilitates the heterogeneous nucleation and interfacial super-assembly of in situ formed mesostructured MOF nanocomposites, serving as structural units, in a loosely packed manner to produce 2D MOF nanosheets with multimodal micro/meso-/macroporous systems. Importantly, this strategy can be extended to prepare other 2D hierarchically porous MOF nanosheets by altering metal-oxo clusters and organic ligands. Benefiting from fast mass transfer and highly accessible Lewis acidic sites, the resultant 2D hierarchically porous UiO-66-NH2 nanosheets deliver a fabulous catalytic yield of approximately 96% on the CO2 cycloaddition of glycidyl-2-methylphenyl ether, far exceeding the yield of approximately 29% achieved using conventional UiO-66-NH2 microporous crystals. This "hard" emulsion-induced interface super-assembly strategy paves a new path toward the rational construction of elaborate 2D nanoarchitecture of hierarchical MOFs with tailored physicochemical properties for diverse potential applications.

Construction of Three-Dimensional Dendritic Hierarchically Porous Metal-Organic Framework Nanoarchitectures via Noncentrosymmetric Pore-Induced Anisotropic Assembly.

As a unique class of modular nanomaterials, metal-organic framework (MOF) nanoparticles have attracted widespread interest for use in various fields because of their diverse chemical functionalities, intrinsic microporosity, and three-dimensional (3D) nanoarchitectures. However, endowing MOF nanomaterials with precisely controlled structural symmetries and hierarchical macro/mesoporosities remains a formidable challenge for the researchers. Herein, we report a facile noncentrosymmetric pore-induced anisotropic assembly strategy to prepare a series of 3D dendritic MOF (UiO-66) nanomaterials with highly controllable structural symmetries and hierarchical macro/meso/microporosities. The synthetic route of these nanomaterials depends on the anisotropic nucleation of MOF spherical nanocones with noncentrosymmetric center-radial channels and their oriented growth to isotropic nanospheres through a continuous increase in radius and solid angle. This strategy enables the controllable fabrication of asymmetric MOF nanostructures with abundant geometries and porous structures by regulating the concentration of amphiphilic triblock copolymer templates. Furthermore, the average pore diameter of the resultant MOF nanospheres can be systematically manipulated in a wide range from 35 to 130 nm by finely tuning the reaction temperature. Meanwhile, the strategy can also be extended to synthesize other MOF nanoparticles with similar architectures. Compared with microporous UiO-66 nanocrystals, the MOF nanoparticles with controllable structural symmetries and macro/meso/microporosities show enhanced catalytic activity in the CO2 cycloaddition reaction. The methodology provides new insights into the rational construction of sophisticated asymmetric open nanostructures of hierarchically porous MOFs for many potential applications.

Regioselective Surface Assembly of Mesoporous Carbon on Zeolites Creating Anisotropic Wettability for Biphasic Interface Catalysis.

The anisotropic surface functionalization of microporous zeolites with mesoporous materials into hierarchically porous heterostructures with distinctive physical and chemical properties is expected to significantly extend their applicability to catalysis. However, the precise control of the surface chemistry of zeolite crystals through site-specific interconnection with mesoporous materials remains a grand challenge. Here, we report a regioselective surface assembly strategy for the region-specific growth of mesoporous polymer/carbon on zeolite nanocrystals. The approach enables controllable regioselective surface deposition of mesoporous polydopamine on the edges, curved surfaces, or/and flat surfaces of the silicalite-1 nanocrystals into exotic hierarchical nanostructures with diverse surface geometries. Upon carbonization, their derived heterostructures with anisotropic surface wettability show amphiphilic properties. As a proof of concept, Pt nanoparticle-encapsulated silicalite-1/mesoporous carbon nanocomposites are tested to be interface-active for forming Pickering emulsions. Significantly, the catalysts show superior catalytic performance in shape-selective hydrogenation of various nitroarenes in a series of biphasic tandem catalytic reactions, giving ∼100% yield of corresponding amine products. The results pave a path toward rational construction of high levels of surface structural complexity in hierarchically porous heterostructures for specific physical and chemical characteristics in diverse applications.

Construction of Single-Crystalline Hierarchical ZSM-5 with Open Nanoarchitectures via Anisotropic-Kinetics Transformation for the Methanol-to-Hydrocarbons Reaction.

We report an anisotropic-kinetics transformation strategy to prepare single-crystalline aluminosilicate MFI zeolites (ZSM-5) with highly open nanoarchitectures and hierarchical porosities. The methodology relies on the cooperative effect of in situ etching and recrystallization on the evolution of pure-silica MFI zeolite (silicalite-1) nanotemplates under hydrothermal conditions. The strategy enables a controllable preparation of ZSM-5 nanostructures with diverse open geometries by tuning the relative rate difference between etching and recrystallization processes. Meanwhile, it can also be extended to synthesize other heteroatom-substituted MFI zeolite nanocages. Compared with conventional ZSM-5 microcrystals, nanocrystals, and nanoboxes, the ZSM-5 nanocages with single-crystalline nature, highly open nanoarchitectures, and hierarchical porosities exhibit remarkably enhanced catalytic lifetime and low coking rate in the methanol-to-hydrocarbons (MTH) reaction.

Ordered Macro-Microporous Metal-Organic Framework Single Crystals and Their Derivatives for Rechargeable Aluminum-Ion Batteries.

Constructing ordered hierarchical porous structures while maintaining their overall crystalline order is highly desirable but remains an arduous challenge. Herein, we successfully achieve the growth of single-crystalline metal-organic frameworks (MOFs) in three-dimensional (3D) ordered macroporous template voids by a saturated solution-based double-solvent-assisted strategy with precise control over the nucleation process. The as-prepared single-crystalline ordered macro-microporous Co-based MOFs (SOM ZIF-67) exhibit an ordered macro-microporous structure with robust single-crystalline nature. Moreover, SOM ZIF-67 can serve as a precursor to derive 3D-ordered macroporous cobalt diselenide@carbon (3DOM CoSe2@C) through a facile carbonization-selenization treatment. The as-derived 3DOM CoSe2@C can well preserve the 3D-ordered macroporous structure of the precursor. More importantly, CoSe2 nanoparticles could be uniformly confined in the conductive ordered macroporous carbon framework, affording regularly interconnected macroporous channels and large surface area. As a result, when evaluated as a cathode material for aluminum-ion batteries, the ordered macroporous structure could not only effectively facilitate the diffusion of large-sized chloroaluminate anions but also increase the contact area with electrolyte and provide more exposed active sites, thereby exhibiting superior reversible rate capacity (86 mA h g-1 at 5.0 A g-1) and remarkable cycling performance (125 mA h g-1 after 1000 cycles at 2.0 A g-1).

Unusual Formation of CoSe@carbon Nanoboxes, which have an Inhomogeneous Shell, for Efficient Lithium Storage.

Hybrid hollow nanostructures with tailored shell architectures are attractive for electrochemical energy storage applications. Starting with metal-organic frameworks (MOFs), we demonstrate a facile formation of hybrid nanoboxes with complex shell architecture where a CoSe-enriched inner shell is intimately confined within a carbon-enriched outer shell (denoted as CoSe@carbon nanoboxes). The synthesis is realized through manipulation of the template-engaged reaction between Co-based zeolitic imidazolate framework (ZIF-67) nanocubes and Se powder at elevated temperatures. By virtue of the structural and compositional features, these unique CoSe@carbon nanoboxes manifest excellent lithium-storage performance in terms of high specific capacity, exceptional rate capability, excellent cycling stability, and high initial Coulombic efficiency.

Designed Formation of Co3O4/NiCo2O4 Double-Shelled Nanocages with Enhanced Pseudocapacitive and Electrocatalytic Properties.

Hollow structures with high complexity in shell architecture and composition have attracted tremendous interest because of their great importance for both fundamental studies and practical applications. Herein we report the designed synthesis of novel box-in-box nanocages (NCs) with different shell compositions, namely, Co3O4/NiCo2O4 double-shelled nanocages (DSNCs). Uniform zeolitic imidazolate framework-67/Ni-Co layered double hydroxides yolk-shelled structures are first synthesized and then transformed into Co3O4/NiCo2O4 DSNCs by thermal annealing in air. Importantly, this strategy can be easily extended to prepare other complex DSNCs. When evaluated as electrodes for pseudocapacitors, the Co3O4/NiCo2O4 DSNCs show a high specific capacitance of 972 F g(-1) at a current density of 5 A g(-1) and excellent stability with 92.5% capacitance retention after 12 000 cycles, superior to that of Co3O4 NCs with simple configuration and Co3O4/Co3O4 DSNCs. Besides, the Co3O4/NiCo2O4 DSNCs also exhibit much better electrocatalytic activity for the oxygen evolution reaction than Co3O4 NCs. The greatly improved electrochemical performance of Co3O4/NiCo2O4 DSNCs demonstrates the importance of rational design and synthesis of hollow structures with higher complexity.

Mesostructured TiO2 Gated Periodic Mesoporous Organosilica-Based Nanotablets for Multistimuli-responsive Drug Release.

A multistimuli-responsive drug carrier is designed and successfully synthesized by self-assembly of thiol-modified periodic mesoporous organosilica (PMO) nanoparticles, coated gold nanoparticles (AuNPs), and mesostructured titanium dioxide (TiO2). Dye-loaded PMO-Au@TiO2 nanotablets are shown to respond to environmental changes (pH, temperature, and light) to achieve controlled release.

Construction of Metal/Zeolite Hybrid Nanoframe Reactors via in-Situ-Kinetics Transformations.

Metal/zeolite hybrid nanoframes featuring highly accessible compartmental environments, abundant heterogeneous interfaces, and diverse chemical compositions are expected to possess significant potential for heterogeneous catalysis, yet their general synthetic methodology has not yet been established. In this study, we developed a two-step in-situ-kinetics transformation approach to prepare metal/ZSM-5 hybrid nanoframes with exceptionally open nanostructures, tunable metal compositions, and abundant accessible active sites. Initially, the process involved the formation of single-crystalline ZSM-5 nanoframes through an anisotropic etching and recrystallization kinetic transformation process. Subsequently, through an in situ reaction of the Ni2+ ions and the silica species etched from ZSM-5 nanoframes, layered nickel silicate emerged on both the inner and outer surfaces of the zeolite nanoframes. Upon reduction under a hydrogen atmosphere, well-dispersed Ni nanoparticles were produced and immobilized onto the ZSM-5 nanoframes. Strikingly, this strategy can be extended to immobilize a variety of ultrasmall monometallic and bimetallic alloy nanoparticles on zeolite nanoframes. Benefiting from the structural and compositional advantages, the resultant hybrid nanoframes with a high loading of discrete Ni nanoparticles exhibited enhanced performance in the hydrodeoxygenation of stearic acid into liquid fuels. Overall, the methodology shares fresh insights into the rational construction of intricate frame-like metal/zeolite hybrid nanoreactors for many potential catalytic applications.

Ultrasmall water-stable CsPbBr3 quantum dots with high intensity blue emission enabled by zeolite confinement engineering.

Ultrasmall CsPbBr3 perovskite quantum dots (PQDs) as promising blue-emitting materials are highly desired for full-color display and lighting applications, but their inferior efficiency and poor ambient stability hinder extensive applications. Herein, a "break-and-repair" strategy has been developed to tightly confine monodispersed ultrasmall CsPbBr3 PQDs in a zeolite. In this strategy, the CsPbBr3 PQDs are introduced into the zeolite via a high temperature evaporation method, wherein the perovskite precursors break the zeolite framework, and amino acids and silane are then used to fix the damaged framework and lock the perovskite QDs within the matrix. By modulating the synthetic conditions to control the growth of CsPbBr3, PQDs with ultrasmall size of 2 nm have been obtained in the zeolite, giving emission centered at 460 nm with a high quantum yield of 76.93%. Strikingly, the PQDs@zeolite composite exhibits water-induced reversible photoluminescence promoted by the coordination between the amino acids and PQDs in a dynamic manner, achieving enhanced water stability (14 days in aqueous solution). This work provides a new perspective for the synthesis of water-stable blue-emitting perovskite composites for potential applications in lighting fields.

A facile dual-template-directed successive assembly approach to hollow multi-shell mesoporous metal-organic framework particles.

Hollow multi-shell mesoporous metal-organic framework (MOF) particles with accessible compartmentalization environments, plentiful heterogeneous interfaces, and abundant framework diversity are expected to hold great potential for catalysis, energy conversion, and biotechnology. However, their synthetic methodology has not yet been established. In this work, a facile dual-template-directed successive assembly approach has been developed for the preparation of monodisperse hollow multi-shell mesoporous MOF (UiO-66-NH2) particles through one-step selective etching of successively grown multi-layer MOFs with alternating two types of mesostructured layers. This strategy enables the preparation of hollow multi-shell mesoporous UiO-66-NH2 nanostructures with controllable shell numbers, accessible mesochannels, large pore volume, tunable shell thickness and chamber sizes. The methodology relies on creating multiple alternating layers of two different mesostructured MOFs via dual-template-directed successive assembly and their difference in framework stability upon chemical etching. Benefiting from the highly accessible Lewis acidic sites and the accumulation of reactants within the multi-compartment architecture, the resultant hollow multi-shell mesoporous UiO-66-NH2 particles exhibit enhanced catalytic activity for CO2 cycloaddition reaction. The dual-template-directed successive assembly strategy paves the way toward the rational construction of elaborate hierarchical MOF nanoarchitectures with specific physical and chemical features for different applications.

Anisotropic Interface Successive Assembly for Bowl-Shaped Metal-Organic Framework Nanoreactors with Precisely Controllable Meso-/Microporous Nanodomains.

Colloidal metal-organic framework (MOF) nanoparticles, with tailored asymmetric nanoarchitectures and hierarchical meso-/microporosities, have significant implications in high-performance nanocatalysts, nanoencapsulation carriers, and intricate assembly architectures. However, the methodology that could achieve precise control over the anisotropic growth of asymmetric MOF particles with tailored distributions of meso- and microporous regions has not yet been established. In this study, we introduce a facile anisotropic interface successive assembly approach to synthesize asymmetric core-shell MOF (ZIF-67) nanobowls with worm-like mesopores in the core and intrinsic micropores in the shell. Our synthesis pathway relies on anisotropic nucleation of mesoporous MOF nanohemispheres on emulsion interfaces through the cooperative assembly of surfactants and MOF precursors. This is followed by the growth of microporous MOF layers on both interfaces of mesoporous cores and emulsion droplets, resulting in a hierarchically porous core-shell nanostructure. By utilizing this multi-interface-driven approach, we enable the creation of diverse geometries and distributions of mesopores and micropores in asymmetric MOF nanoarchitectures. The obtained bowl-like meso-/microporous core-shell ZIF-67 particles exhibit enhanced catalytic activity for CO2 cycloaddition, attributed to reactant accumulation within the bowl-like architecture, active site accessibility in the open mesoporous core, and improved structural stability. Overall, our study provides insights and inspiration for exploring the intricate asymmetric nanostructures of hierarchically porous MOFs with diverse potential applications.

Fungus-mediated green synthesis of silver nanoparticles using Aspergillus terreus.

The biosynthesis of nanoparticles has received increasing attention due to the growing need to develop safe, cost-effective and environmentally friendly technologies for nano-materials synthesis. In this report, silver nanoparticles (AgNPs) were synthesized using a reduction of aqueous Ag(+) ion with the culture supernatants of Aspergillus terreus. The reaction occurred at ambient temperature and in a few hours. The bioreduction of AgNPs was monitored by ultraviolet-visible spectroscopy, and the AgNPs obtained were characterized by transmission electron microscopy and X-ray diffraction. The synthesized AgNPs were polydispersed spherical particles ranging in size from 1 to 20 nm and stabilized in the solution. Reduced nicotinamide adenine dinucleotide (NADH) was found to be an important reducing agent for the biosynthesis, and the formation of AgNPs might be an enzyme-mediated extracellular reaction process. Furthermore, the antimicrobial potential of AgNPs was systematically evaluated. The synthesized AgNPs could efficiently inhibit various pathogenic organisms, including bacteria and fungi. The current research opens a new avenue for the green synthesis of nano-materials.

Terminating effects of organosilane in the formation of silica cross-linked micellar core-shell nanoparticles.

One advanced synthesis strategy for monodisperse silica cross-linked micellar core-shell nanoparticles (SCMCSNs) involves the use of organosilane termination agent R(n)Si(OR')(4 - n). In this study, we investigated the effects of the organosilane termination agent in the formation of SCMCSNs. Experimental data (synthesis results, (29)Si MAS NMR, molecule probe fluorescence spectra, etc.) from a synthesis system with Pluronic F127 as the template indicate that organosilane either covers or reacts with the surface Si-OH groups of nanoparticles. The reduction of reactive surface Si-OH groups helps to stabilize nanoparticles by avoiding aggregation. The terminating behavior of organosilane is determined by its molecular structure, including (1) the value of n, (2) the length of hydrocarbon chain R, and (3) the charge of R. Effective organosilane termination agents are also applicable to other synthesis mixtures such as the systems using Si(OC(2)H(4)OH)(4) as the silica source or F108 or Brij 700 as the template. Furthermore, we can obtain monodisperse nanoparticles by using the trisodium salt of triacetic acid N-(trimethoxysilylpropyl)ethylenediamine (TANED), which acts not only as a termination agent for the successful synthesis of SCMCSNs but also as a functional group to improve the performance of SCMCSNs in potential applications.

Spatially Separated Bifunctional Cocatalysts Decorated on Hollow-Structured TiO2 for Enhanced Photocatalytic Hydrogen Generation.

Efficient charge separation can promote photocatalysis of semiconductors. Herein, a hollow-structured TiO2 sphere decorated with spatially separated bifunctional cocatalysts was designed, which exhibited enhanced photocatalytic hydrogen generation. Ultrasmall-sized MOx (M = Pd, Co, Ni, or Cu) nanoparticles (NPs) were first introduced into a zeolite via confinement synthesis, and then, hollow TiO2 was fabricated by using the zeolite as a sacrificial template forming MOx@TiO2. Finally, Pt NPs were decorated on the outer shell, giving rise to MOx@TiO2@Pt, in which the MOx NPs and Pt NPs acted as hole capturers and electron sinks, respectively. Thanks to the enhanced light harvesting of the hollow structure and improved charge separation induced by the smaller-sized cocatalysts as well as spatially separated bifunctional cocatalysts, the as-prepared PdOx@TiO2@Pt catalyst exhibited a superior photocatalytic hydrogen-generation property (0.45 mmol h-1). This work demonstrates the advantage of the spatially separated bifunctional cocatalysts in enhancing the photocatalytic properties of semiconductors.

Formation of Ni-Co-MoS2 Nanoboxes with Enhanced Electrocatalytic Activity for Hydrogen Evolution.

Nickel and cobalt incorporated MoS2 nanoboxes are synthesized via the reaction between Ni-Co Prussian blue analogue nanocubes and ammonium thiomolybdate. Due to the structural and compositional advantages, these well-defined nanoboxes manifest enhanced electrochemical activity as an electrocatalyst for hydrogen evolution reaction.

A sulfur host based on titanium monoxide@carbon hollow spheres for advanced lithium-sulfur batteries.

Lithium-sulfur batteries show advantages for next-generation electrical energy storage due to their high energy density and cost effectiveness. Enhancing the conductivity of the sulfur cathode and moderating the dissolution of lithium polysulfides are two key factors for the success of lithium-sulfur batteries. Here we report a sulfur host that overcomes both obstacles at once. With inherent metallic conductivity and strong adsorption capability for lithium-polysulfides, titanium monoxide@carbon hollow nanospheres can not only generate sufficient electrical contact to the insulating sulfur for high capacity, but also effectively confine lithium-polysulfides for prolonged cycle life. Additionally, the designed composite cathode further maximizes the lithium-polysulfide restriction capability by using the polar shells to prevent their outward diffusion, which avoids the need for chemically bonding all lithium-polysulfides on the surfaces of polar particles.

Megranate-like nanoreactor with multiple cores and an acidic mesoporous shell for a cascade reaction.

Megranate-like nanoparticles possess a unique structure that is composed of multiple cores and shells, which is different from simple yolk-shell nanoparticles. Megranate-like nanoparticles can combine the properties of each component and be used as nanoreactors. This study describes the preparation of bifunctional megranate-like nanoreactors, consisting of multiple metal cores and thiol modified mesoporous SiO2 shells. Different metal nanoparticles (Pd, Pt, Au) can be incorporated into the structure as cores, and the thiol group in the shells can be oxidized to acidic -SO3H. The megranate-like nanoparticles show good bifunctional catalytic properties and recyclability in a cascade catalytic reaction for the desired benzimidazole derivative. Moreover, the individual components of the megranate-like nanoparticles also show good catalytic activities in the hydrogenation reduction of nitro-aromatics and the deprotection reaction of benzaldehyde dimethyl acetal.

Tailored synthesis of hierarchical spinous hollow titania hexagonal prisms via a self-template route.

Novel hierarchical spinous hollow titania hexagonal prisms are prepared through a facile fluorine-free self-template route using Ti2O3(H2O)2(C2O4)·H2O (TC) hexagonal prisms as a precursor. The hollowing transformation can be elucidated by the template-free Kirkendall effect, and diverse nanostructures can also be synthesized during the conversion process, such as the spinous core-shell and yolk-shell nanocomposites. The hierarchical hollow microparticles are composed of ultrathin nanobelts of 50-100 nm in length and about 10 nm in thickness, and possess a higher surface area of up to 163 m(2) g(-1) compared with solid microparticles (49 m(2) g(-1)). This type of morphology is of great interest for lithium-ion batteries because of its shorter length for Li(+) transport and better electrode-electrolyte contact.

A versatile cooperative template-directed coating method to construct uniform microporous carbon shells for multifunctional core-shell nanocomposites.

A very simple cooperative template-directed coating method is developed for the preparation of core-shell, hollow, and yolk-shell microporous carbon nanocomposites. Particularly, the cationic surfactant C16TMA(+)·Br(-) used in the coating procedure improves the core dispersion in the reaction media and serves as the soft template for mesostructured resorcinol-formaldehyde resin formation, which results in the uniform polymer and microporous carbon shell coating on most functional cores with different surface properties. The core diameter and the shell thickness of the nanocomposites can be precisely tailored. This approach is highly reproducible and scalable. Several grams of polymer and carbon nanocomposites can be easily prepared by a facile one-pot reaction. The Au@hydrophobic microporous carbon yolk-shell catalyst favors the reduction of more hydrophobic nitrobenzene than hydrophilic 4-nitrophenol by sodium borohydride, which makes this type of catalyst@carbon yolk-shell composites promising nanomaterials as selective catalysts for hydrophobic reactants.