Metal-organic frameworks as selectivity regulators for hydrogenation reactions

Breakthrough in plasmonic enhanced MOFs: Design, synthesis, and catalytic mechanisms for various photocatalytic applications

Integrating metal-organic framework MOFs with plasmonic nanoparticles (NPs) addresses a significant shortcoming of standard plasmonic platforms: their low efficacy with non-adsorbing compounds. The corporation of porous MOFs complements the plasmonic characteristics, allowing for a broader range of applications. This study highlights recent advancements in the design, synthesis, structural engineering, and functional properties of heterostructures combining plasmonic NPs with MOFs, focusing on their plasmonic and catalytic reaction behaviors. These developments have greatly enhanced the protentional of plasmonic NPs-MOFs heterojunction in nanofabrication and various applications, such as chemical sensing techniques like localized surface plasmon resonance (LSPR) surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorbance (SEIRA). Additionally, the study thoroughly examines the interface interaction and photocatalytic performance of plasmonic NPs-MOFs. Various practical applications of plasmonic NPs-MOFs heterojunction are explored, including their promising role in tackling environmental challenges like industrial water pollution. Furthermore, we have a detailed discussion of various photocatalysis processes, including water splitting, CO2 reduction, pollutant degradation, and various sensing applications. Identifying current limitations and outlining future research directions to bridge existing knowledge gaps, including interface interaction, photocatalytic performance, and practical applications providing a comprehensive understanding, are the main aims of this review to inspire the development of next-generation plasmonic NPs-MOFs materials. It concludes by discussing future directions and challenges in composite development, emphasizing their potential to provide sustainable and efficient solutions for environmental remediation and energy conversion.

Electron-deficient defect sites in polyoxometalate-based metal-organic frameworks induced by atom substitution-modulated host-guest interaction

The strategic introduction of defects in polyoxometalate-based metal-organic frameworks (POM@MOFs) enables synergistic catalytic effects between POMs and defect sites, achieving catalytic functions unattainable by either component alone. However, the complexity of the POM@MOFs synthetic system makes the controlled construction of defects more challenging than in conventional MOFs. Herein, we develop an atomic substitution-modulated host-guest interaction strategy for controlled synthesis of electron-deficient defect sites in POM@MOFs with tunable missing-linker content. Specifically, the gradual substitution of Mo atoms with V atoms in H3PMo12O40 (PMo12) enhances the nucleophilicity of surface oxygen species, thereby strengthening the interaction between POMs and Zr6-oxo clusters in UiO-67. This enhanced interaction induces varying degrees of ligand loss through coordination competition of POMs with organic ligands during the self-assembly of POM@UiO-67. Meanwhile, POMs acting as electron sponges withdraw electrons from UiO-67, resulting in lower electron density at defect sites compared to traditional defective UiO-67. The induced defect sites exhibit superior catalytic performance in the transfer hydrogenation of cinnamaldehyde, due to a significantly reduced hydrogen transfer energy barrier. This work provides a new perspective for designing crystalline porous catalysts with synergistic effects based on the modulation of host-guest interaction.

Emerging heterostructures derived from metal-organic frameworks for electrochemical energy storage: Progresses and perspectives

Heterostructures are a novel class of advanced materials have attracted considerable attention because they combine components with different structures and properties, exhibiting unique activity and function due to synergistic interactions at the interface. Over the last decade, there has been increasing research interest in constructing advanced heterostructures nanomaterials possessing efficient charge/ion transportation, optimize ion absorption behavior and rich accessible active sites for electrochemical energy storage (EES). Nonetheless, the conventional methodology for constructing heterostructures typically involves the self-assembly of active materials and conductive components, which poses significant challenges in achieving large-scale, uniformly atomically matched interfaces. Moreover, the development of heterostructures via transformation of the printine material into distinct phases can effectively address this limitation. Based on this, Metal-organic frameworks (MOFs), a class of porous materials with an inherently large surface area, uniform and adjustable cavities, and customizable chemical properties, have been widely used as precursors or templates for the preparation of heterostructure materials. Although there are some previous reviews on MOF-derived heterostructures for EES, they rarely focus on the structural engineering of MOF-derived heterostructures materials and their advanced characterization for EES. In this review, we summarize and discuss recent progress in the design and structural engineering (including morphology engineering, heteroatom doping, and defect engineering) of MOF-derived heterostructures and their applications in EES (e.g., supercapacitors, lithium-ion batteries, sodium-ion batteries, aluminum-ion batteries, aqueous Zn-ion batteries, etc.). The review concludes with a perspective on the remaining challenges and potential opportunities for future research.

Atomic Scale Engineering of Multivalence-State Palladium Photocatalyst for Transfer Hydrogenation with Water as a Proton Source

Hydrogenation reactions are fundamental in the fine chemical, pharmaceutical, and petrochemical industries, however heavily relying on H2 gas at high temperatures and pressures, incurring large energy and carbon costs. Photocatalytic transfer hydrogenation, using water as a proton source, offers a greener alternative, but existing photocatalysts often suffer from modest yields, limited selectivity, and narrow substrate scope. Additionally, they often require co-activation, such as Mg-activated water or non-sustainable hydrogen feeds. Here, a photocatalyst is introduced that offers high yields and selectivities across a broad spectrum of organic compounds. The developed photocatalyst is a multivalence palladium superstructure with ultrasmall Pd0 nanoparticles enveloped by isolated Pd2+/Pd4+ atoms within a carbon-nitride matrix. Mechanistic studies reveal that the redox-flexible Pd single atoms, with triethylamine as an electronic modulator, attract photogenerated holes for water oxidation, while Pd0 nanoparticles facilitate hydrogen transfer to the unsaturated bonds of the organic molecules. The cooperative and dynamic behavior of Pd centers during catalysis, involving transitions among Pd+2, Pd+3, and Pd+4 states, is validated using operando electron paramagnetic resonance spectroscopy. This multivalent palladium catalyst represents a conceptual advance in photocatalytic transfer hydrogenation with water as a hydrogen source, holding promise for sustainable hydrogenation processes in the chemical industry.

Defect engineered Ti-MOFs and their applications

Titanium-based metal-organic frameworks (Ti-MOFs) hold great potential for applications in photocatalysis and other fields, owing to Ti's abundant reserves, low toxicity, and excellent photocatalytic and redox activity. However, Ti's strong affinity for oxygen often leads to Ti-MOFs being fully coordinated with ligands, which limits their catalytic and separation performance. Defect engineering provides an effective strategy to enhance the functionality of MOFs by introducing structural imperfections. Despite this, the synthesis of new Ti-MOFs and the incorporation of defects remain challenging due to the complex hydrolysis and reaction processes of Ti precursors and the uncertainty of Ti cluster formation. This review categorizes Ti-MOFs according to their diverse cluster structures, which play a key role in the development of new frameworks and defect engineering. It also examines various defect construction methods and their applications. Finally, insights from defect-engineered Zr-MOFs are discussed to inspire future advancements in the synthesis and application of defective Ti-MOFs.

Phenothiazine-dioxide-based Cu-MOFs: preserving porosity through the incorporation of substituents into organic linkers

Metal-organic frameworks (MOFs) with high porosity usually suffer from problems associated with pore collapse upon activation. Preserving the porosity can thus be considered an important subject to be resolved with regard to the application of MOFs as industrial materials. Herein, we report the preservation of the porosity of phenothiazine-dioxide-based Cu-MOFs via the incorporation of substituents into the organic linkers.

Modern organic transformations: heterogeneous thermocatalysis or photocatalysis?

Organic transformation driven by heterogeneous catalysis is of crucial significance in both fundamental research and modern industrial production of fine chemicals. Thermocatalysis offers excellent applications due to its high activity and excellent scalability, yet still faces significant challenges toward the goals of high efficiency, energy-saving and sustainability. Recently, photocatalysis has emerged as a promising alternative for addressing these issues in a green and economical manner. In practice, the selection of an appropriate catalytic system is a critical factor that can influence the chemical process on multiple levels significantly. In this review, we aim to present a tutorial demonstration about the critical comparison between thermo- and photocatalytic terms for organic transformation. We begin by outlining the basic principles in thermo- and photocatalytic fundamentals, together with summarizing the general advantages and disadvantages of each. Subsequently, given the high sustainability and potentiality exhibited by the photocatalytic process, we present its representative applications including oxidation, reduction, coupling, and cleavage series. The general reaction conditions and activities observed in thermocatalysis for similar reactions are also introduced for comparison. The understanding of reaction mechanisms and the resulting regulations toward activity and selectivity are specifically discussed. Finally, future perspectives of heterogeneous photocatalytic terms for practical applications are elucidated.

Atomically Dispersed Metal Interfaces for Analytical Chemistry

ConspectusEngineering sensing interfaces with functional nanomaterials have aroused great interest in constructing novel analytical platforms. The good catalytic abilities and physicochemical properties allow functional nanomaterials to perform catalytic signal transductions and synergistically amplify biorecognition events for efficient target analysis. However, further boosting their catalytic performances poses grand challenges in achieving more sensitive and selective sample assays. Besides, nanomaterials with abundant atomic compositions and complex structural characteristics bring about more difficulties in understanding the underlying mechanism of signal amplification. Atomically dispersed metal catalysts (ADMCs), as an emerging class of heterogeneous catalysts, feature support-stabilized isolated metal catalytic sites, showing maximum metal utilization and a strong metal-support interfacial interaction. These unique structural characteristics are akin to those of homogeneous catalysts, which have well-defined coordination structures between metal sites with synthetic or biological ligands. By integrating the advantages of heterogeneous and homogeneous catalysts, ADMCs present superior catalytic activity and specificity relative to the nanoparticles formed by the nonuniform aggregation of active sites. ADMC-enabled sensing platforms have been demonstrated to realize advanced applications in various fields. Notably, the easily tunable coordination structures of ADMCs bring more opportunities to improve their catalytic performance, further moving toward efficient signal transduction ability. Besides, by leveraging their inherent physicochemical properties and various detection strategies, ADMC-enabled sensing interfaces not only achieve enhanced signal transductions but also show diversified output models. Such superior functions allow ADMC-enabled sensing platforms to access the goal of high-performance detection of trace targets and making significant progress in analytical chemistry.In this Account, we provide an overview of recent progress in atomically dispersed metal-involved interfaces in analytical chemistry. The engineering strategies focused on regulating metal centers, integrating multisite synergy, and tuning charge transport pathways are discussed to boost the catalytic activity and specificity of ADMCs as well as expand their multifunctionality. Combined with various transduction models, including colorimetry, electrochemistry, chemiluminescence, electrochemiluminescence, and photoelectrochemistry, ADMC-based sensors achieve efficient detection of diverse analytes. Specifically, the underlying mechanisms of signal transduction are highlighted. Finally, the perspective and challenges of the ADMC-enabled interface for analytical chemistry are further proposed. We hope that this Account will afford significant inspiration toward the design of ADMCs and the decoding of the improved sensing interfaces.

Chemical Vapor Deposition Strategy of Fe-N-C Nanotubes for the Oxygen Evolution Reaction

The conversion of metal-nitrogen-carbon (M-N-C) nanoparticles derived from conventional metal-organic frameworks (MOFs) into self-supporting and well-defined metal-nitrogen-carbon (M-N-C) superstructures is essential for various functional applications but remains a significant challenge. In this study, a versatile chemical vapor deposition (CVD) strategy is developed for solvent-free synthesis of self-supporting carbonaceous nanotubes doped with metal and nitrogen (MNCT). The stable carbonaceous nanotubes doped with Fe and N (FeNCT) fabricated here exhibit excellent electrocatalytic performances for the oxygen evolution reaction (OER) and outperform the carbonaceous film doped with Fe and N grown on carbon foil directly (FeNC/CF), which demonstrates the advantages of the superstructure of FeNCT. This strategy also provides a way to tailor the metal-nitrogen-carbon nanotubes (MNCT) catalyst according to the feature of the reactor and exhibits many advantages, such as wide applicability and facile scalability.

Investigating the Physical Adsorption of DCPD/Furfural and H2 Adsorption-Dissociation Behaviors in RE-MOFs

Metal-organic frameworks (MOFs) have emerged as promising catalysts in the hydrogenation of bicyclopentadiene (DCPD) and furfural. The physical adsorption behaviors of substrate molecules and H2 within the pore structures of MOFs significantly influence the efficacy of subsequent catalytic reactions. This study employs molecular dynamics (MD) simulations to identify the optimal temperature and pressure conditions for the adsorption of DCPD and H2, as well as furfural and H2, within rare-earth-element-based MOFs (RE-MOFs). By analyzing the physical adsorption characteristics of 1538 RE-MOFs, we investigate the correlation between pore structures and adsorption capabilities. This exploration has led to the identification of 10 RE-MOF structures that demonstrate superior physical adsorption performance for both DCPD and furfural. Following this initial evaluation, density functional theory (DFT) calculations were conducted to determine the chemisorption energies of H2 molecules on these 10 selected RE-MOF structures. Notably, the structure identified as "JALLEQ_clean" exhibited the most optimal overall adsorption performance. This study elucidates the quantitative relationship between the pore structure of RE-MOFs and their physical adsorption performance, clarifying the influence of porosity parameters on adsorption capacity and highlighting the advantages of cluster-type structures in mass transfer and adsorption. The findings provide theoretical guidance for developing high-performance RE-MOF catalysts and offer new insights for the rational design of MOF-based catalytic materials.

Ionic-Fence Effect in Au Nanoparticle-Loaded UiO-66 Metal-Organic Frameworks for Highly Chemoselective Hydrogenation

The chemoselective reaction are vital for fine chemicals, which requires economical and environmentally friendly catalysts. In order to improve the selectivity of multi-reaction competition, herein, we propose a novel ionic-fence strategy to synthesize heterogeneous catalyst for efficient hydrogenation. Practically, UIO-66 metal-organic frameworks (MOF) modified with pyridinium-linker has been constructed through post-synthetic chains with paired anion via quaternization and ion exchange to form ionic-fence MOF (IFMOF-Cl), which can manage the adsorption mode of nitro substrate, further confine the formation of metal nanoparticles with high dispersity. The optimal Au@IFMOF-Cl catalyst demonstrates satisfactory selectivity for hydrogenation of nitro group compared to acetylene group in 4-nitrophenylacetylene. Specifically, it owns a high yield of 4-aminophenylacetylene (~97 %) with ultra-high catalytic efficiency (3880 h-1 TOF) and long stability, far superior to other catalysts without ionic fence effect. Adsorption experiments and density functional theory studies reveal that the incorporation of ionic fence could modulate the adsorption energy of nitro group, which is responsible for the high selectivity enhancement. Notably, this ionic-fence strategy exhibits comprehensive universality towards a wide range of substrates (23 kinds in total), providing a promising avenue for precisely engineering the internal microenvironments of catalysts to achieve highly selective synthesis of fine chemicals.

Metal pyrazolate frameworks: crystal engineering access to stable functional materials

As the focus evolves from structure discovery/characterization (what it is) to property/performance exploration (what it is for), the pursuit of stable functional metal-organic frameworks (MOFs) has been ongoing in terms of both fundamental research and industrial implementation. Under the guidance of crystal engineering principles, a plethora of research has developed pyrazolate MOFs (metal pyrazaolate frameworks, MPFs) featuring strong coordination M-N bonding. This attribution helps them retain their structures and functions under the alkaline conditions required for practical use. Based on poly-topic pyrazolate ligands, various classic MOFs, such as Co(bdp), Fe2(BDP)3, Ni8L6, PCN-601, and BUT-55, to name a few, have revealed fascinating architectures, intriguing properties, and record-breaking performances in applications during the past decade. This review will present the full scope of MPFs to date: (1) the superiority and significance of constructing MPFs through the crystal engineering approach, (2) synthetic strategies adopted in building and/or modifying MPFs, (3) structural features and stability of the MPF community, and (4) potential applications in energy and environmental related fields. The future opportunities of MPFs are also discussed for designing the next-generation of smart materials. Overall, this review attempts to provide insights and guidelines for the customization of pyrazolate-based MOFs for specific purposes, which would also promote the development of stable functional porous materials for addressing societal challenges.

Sandwiching of MOF nanoparticles between graphene oxide nanosheets among ice grains

Current strategies to tailor the formation of nanoparticle clusters require specificity and directionality built into the surface functionalization of the nanoparticles by involved chemistries that can alter their properties. Here, we describe a non-disruptive approach to place nanomaterials of different shapes between nanosheets, i.e., nano-sandwiches, absent any pre-modification of the components. We demonstrate this with metal-organic frameworks (MOFs) and silicon oxide (SiO2) nanoparticles sandwiched between graphene oxide (GO) nanosheets, MOF-GO and SiO2-GO, respectively. For the MOF-GO, the MOF shows significantly enhanced conductivity and retains its original crystallinity, even after one-year exposure to aqueous acid/base solutions, where the GO effectively encapsulates the MOF, shielding it from polar molecules and ions. The MOF-GOs are shown to effectively capture CO2 from a high-humidity flue gas while fully maintaining their crystallinities and porosities. Similar behavior is found for other MOFs, including water-sensitive HKUST-1 and MOF-5, promoting the use of MOFs in practical applications. The nanoparticle sandwich strategy provides opportunities for materials science in the design of nanoparticle clusters consisting of different materials and shapes with predetermined spatial arrangements.

Unlocking Advanced Architectures of Single-Crystal Metal-Organic Frameworks

The synthesis of metal-organic frameworks (MOFs) with diverse geometries has captivated considerable interest due to their manifestation of novel and extraordinary properties. While much progress has been made in shaping regular polyhedral single-crystal MOFs, the creation of more complex, topologically intricate nanostructures remains a largely unexplored frontier. Here, we present a refined site-specific anisotropic assembly and etching co-mediation approach to fabricate a series of hierarchical MOF nanohybrids and single-crystal MOFs. This approach yields ZIF-8&mSiO2 nanohybrids with diverse topologies, alongside derived single-crystal MOF nanoparticles exhibiting intricate morphologies such as hexapods, nested nanocages, and octopods. Our method involves the selective growth of six mSiO2 nanoplates on the {100} facets of ZIF-8 nanocubes, forming the cubic-shaped ZIF-8&mSiO2 nanohybrids, with the concurrent etching of the {110} facets of initial ZIF-8 nanocubes. By fine-tuning this balance between the growth and etching, we achieved precise morphological control, transforming cubic nanohybrids into intricate hexapods nanohybrids. Additionally, secondary epitaxial growth of homo- or hetero-MOFs on these hybrids led to ZIF-8&mSiO2&MOF composites with six mSiO2 inlays. Finally, selective alkaline etching of the mSiO2 compartments result in single-crystal MOF nanoparticles with unprecedented and sophisticated morphologies, such as hexapods, nested nanocages, octopods. This work advances the field of MOF nanostructure design, opening new avenues for the development of sophisticated, multifunctional materials.

Tailoring Atomically Precise Gold Nanoclusters for Boosting Selective Hydrogenation of Nitrostyrene with H2

Hydrogenation reactions represent some of the most extensively studied topics within the field of catalysis. A novel alkynyl and phosphine coprotected [Au34(PhC≡C)14(Ph3P)6](SO3CF3)2(1) nanocluster has been synthesized, and its structure was determined by single crystal X-ray diffraction (SCXRD). Density functional theory calculation shows that 1 features an 18-electron superatomic molecule character with a configuration of (1σ)2(1n)2(1π)2(2σ)2(1σ*)2(3σ)2(2n)2(3n)2(1π*),2 which is significantly different from previously reported 18-electron metal nanoclusters. In comparison with some gold nanoclusters with similar composition or size but different ligands or surface coordination structures, except for the ligand effect (different kinds of ligands), the surface coordination structure involving the Au(I) sites derived from the PhC≡C-Au-C≡CPh monomeric staple motif and the steric hindrance of PhC≡C and Ph3P on the surface of 1, and the special electronic structure play a critical role in ensuring the enhanced catalytic performance of 1/TiO2 toward the chemoselective hydrogenation of 4-nitrostyrene with H2. The turnover frequency (TOF) of 1322.5 h-1 and the turnover number (TON) of 23500 represent the highest values observed among the gold nanocluster-based catalysts toward the same reaction. It presents an example of tailoring the surface coordination structure to modulate the catalytic performance, and offers valuable insights for the rational design and synthesis of catalysts to trade off the catalytic activity and selectivity at the atomic level.

Porous Microreactor Chip for Photocatalytic Seawater Splitting over 300 Hours at Atmospheric Pressure

Photocatalytic seawater splitting is an attractive way for producing green hydrogen. Significant progresses have been made recently in catalytic efficiencies, but the activity of catalysts can only maintain stable for about 10 h. Here, we develop a vacancy-engineered Ag3PO4/CdS porous microreactor chip photocatalyst, operating in seawater with a performance stability exceeding 300 h. This is achieved by the establishment of both catalytic selectivity for impurity ions and tailored interactions between vacancies and sulfur species. Efficient transport of carriers with strong redox ability is ensured by forming a heterojunction within a space charge region, where the visualization of potential distribution confirms the key design concept of our chip. Moreover, the separation of oxidation and reduction reactions in space inhibits the reverse recombination, making the chip capable of working at atmospheric pressure. Consequently, in the presence of Pt co-catalysts, a high solar-to-hydrogen efficiency of 0.81% can be achieved in the whole durability test. When using a fully solar-driven 256 cm2 hydrogen production prototype, a H2 evolution rate of 68.01 mmol h-1 m-2 can be achieved under outdoor insolation. Our findings provide a novel approach to achieve high selectivity, and demonstrate an efficient and scalable prototype suitable for practical solar H2 production.

MOF-Based Dual-Layer Pickering Emulsion: Molecular-Level Gating of Water Delivery at Water-Oil Interface for Efficient Photocatalytic Hydrogenation Using H2O as a Hydrogen Source

Biphasic system not only presents a promising opportunity for complex catalytic processes, but also is a grand challenge in efficient tandem reactions. As an emerging solar-to-chemical conversion, the visible-light-driven and water-donating hydrogenation combines the sustainability of photocatalysis and economic-value of hydrogenation. However, the key and challenging point is to couple water-soluble photocatalytic hydrogen evolution reaction (HER) with oil-soluble hydrogenation. Herein, we employed metal-organic frameworks (MOFs) and CdS nanorods to construct a MOF-CdS dual-layer Pickering emulsion (water in oil, W/O), which compartmented aqueous phase for photocatalytic HER and oil phase for hydrogenation. The hydrophobic MOF and hydrophilic CdS were isolated at the inner and outer layers of W/O emulsion, respectively. The molecularly regulated hydrophobicity of MOF controlled the water delivery onto CdS photocatalysts, which realized the synergistic regulation of HER and hydrogenation. In the photocatalytic hydrogenation of cinnamaldehyde, the highest yield of MOF-CdS Pickering emulsion reached 187.37 mmol ⋅ g-1 ⋅ h-1, 30 times that of the counterpart without emulsion (6.44 mmol ⋅ g-1 ⋅ h-1). Its apparent quantum yield reached 43.24 % without co-catalysts. To our knowledge, this performance is at a top-level so far. Our work realized the precise regulation of water-oil interface to effectively couple two reactions in different phases, providing new perspective for challenging tandem catalysis.

Immobilization of β-glucosidase and β-xylosidase on inorganic nanoparticles for glycosylated substances conversion

There are abundant glycosylated substances such as cellulose, hemicellulose, and phytochemical glycosides in plants, which could be converted into functional chemicals such as monosaccharides, oligosaccharides, and bioactive aglycones by cleavage of glycosidic bonds using glycoside hydrolases (GHs). Among those GHs, β-glucosidase and β-xylosidase are the rate-limiting enzymes for degrading cellulose and hemicellulose, respectively, and can convert a variety of glycosylated substances. These two enzymes play important roles in the high value use of plant resources and have great potential applications. However, the fragility of enzymes suggests there is an urgent need to improve the activity, stability and reusability of GHs under industrial conditions. Enzyme immobilization is an efficient approach to meet the need. Inorganic materials are preferred carriers for enzyme immobilization, since they possess high surface area, pore size, stability and long service life. Recently, many reports have showed that GHs immobilized on inorganic materials exhibit potential applications on industry and will benefit the process economy. The present review provides an overview of these reports from the perspectives of materials, strategies, activities, stability and reusability, as well as an insight into the related mechanisms, with a view to providing a reference for the GHs immobilization and their applications.

Design and engineering of microenvironments of supported catalysts toward more efficient chemical synthesis

Catalytic species such as molecular catalysts and metal catalysts are commonly attached to varieties of supports to simplify their separation and recovery and accommodate various reaction conditions. The physicochemical microenvironments surrounding catalytic species play an important role in catalytic performance, and the rational design and engineering of microenvironments can achieve more efficient chemical synthesis, leading to greener and more sustainable catalysis. In this review, we highlight recent works addressing the topic of the design and engineering of microenvironments of supported catalysts, including supported molecular catalysts and supported metal catalysts. Six types of materials, including oxide nano/microparticle, mesoporous silica nanoparticle (MSN), polymer nanomaterial, reticular material, zeolite, and carbon-based nanomaterial, are widely used as supports for the immobilization of catalytic species. We summarize and discuss the synthesis and modification of supports and the positive effects of microenvironments on catalytic properties such as metal-support interaction, molecular recognition, pseudo-solvent effect, regulating mass transfer, steric effect, etc. These design principles and engineering strategies allow access to a better understanding of structure-property relationships and advance the development of more efficient catalytic processes.

Ligand-Shell Cooperativity in a Bilayer Silica-Sandwiched Mixed-Metals Nanocatalyst Design for Absolute Selectivity Switch

Unlike homogeneous metal complexes, achieving absolute control over reaction selectivity in heterogeneous catalysts remains a formidable challenge due to the unguided molecular adsorption/desorption on metal-surface sites. Conventional organic surface modifiers or ligands and rigid inorganic and metal-organic porous shells are not fully effective. Here, we introduce the concept of "ligand-porous shell cooperativity" to desirably switch reaction selectivity in heterogeneous catalysis. We present a nanocatalyst design strategy consisting of bilayer silica-sandwiched 2D mixed metal islands. The intimate 2D/2D nanoscale interfacing between porous silica layers and flat island-like mixed-metal sites, combined with organic ligands, creates a nanoconfined microenvironment that enables reliable control of molecular orientation-dependent reactivity, affording the desired product in 100% selectivity. This design simultaneously leverages the hydrophobicity and flexibility of organic ligands and the nanoscale geometric rigidity of the pores inside the inorganic silica shell. Our strategy is effective with simple amorphous silica, random Cu-alloy, and commonly used metal-coordinating ligands. We demonstrate the applicability in industrially significant reactions: selective hydrogenation of alkynes, α,β-unsaturated esters/aldehydes, and nitroarenes. Our findings offer the valuable scope of a multicomponent compact nanoscale design strategy in next-generation switchable, sustainable, and recyclable catalysis.

Interfacial fluid manipulation with bioinspired strategies: special wettability and asymmetric structures

The inspirations from nature always enlighten us to develop advanced science and technology. To survive in complicated and harsh environments, plants and animals have evolved remarkable capabilities to control fluid transfer via sophisticated designs such as wettability contrast, oriented micro-/nano-structures, and geometry gradients. Based on the bioinspired structures, the on-surface fluid manipulation exhibits spontaneous, continuous, smart, and integrated performances, which can promote the applications in the fields of heat transfer, microfluidics, heterogeneous catalysis, water harvesting, etc. Although fluid manipulating interfaces (FMIs) have provided plenty of ideas to optimize the current systems, a comprehensive review of history, classification, fabrication, and integration focusing on their interfacial chemistry and asymmetric structure is highly required. In this review, we systematically introduce development and highlight the state-of-the-art progress of bioinspired FMIs. Firstly, the biological prototype and development timeline are presented, and the underlying mechanism of on-surface fluid control on versatile structures is analyzed. Secondly, the definition and classification of FMIs as well as the strategy for controlling fluid/interface interaction are discussed. Thirdly, emergent applications of FMIs in practical scenarios including fog/vapor collection, fluid diodes, interfacial catalysis, etc. are presented. Furthermore, the challenges and prospects of interfacial liquid manipulation are concluded. We envision that this review should provide guidance for the incorporation of FMIs into suitable situations, which enlightens interdisciplinary research and practical applications in the fields of interface chemistry, materials design, bionic science, fluid dynamics, etc.

B, N Codoped Defective Reduced Graphene Oxide as a Highly Efficient Frustrated Lewis Pairs Catalyst for the Selective Hydrogenation of α,β-Unsaturated Aldehydes to Unsaturated Alcohols

The development of all-solid-state frustrated Lewis pairs (FLPs) metal-free hydrogenation catalysts with excellent activity and stability remains a significant challenge. In this work, B, N codoped FLPs catalysts (De-rGO-NxBy) were prepared by the strategy of fabricating carbon defects and heteroatom doping on the surface of reduced graphene oxide and applied in the selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols. It was found that electron-rich pyridine-N (Lewis base) and adjacent electron-deficient B-N (Lewis acid) sites could be constructed on the surface of reduced graphene oxide using dicyandiamide and metaboric acid as N and B sources, thus forming FLPs sites. More importantly, the constructed carbon defects could facilitate the formation of pyridinic-N/B-N FLPs sites, thereby improving the catalytic hydrogenation activity and the selectivity to unsaturated alcohols. Furthermore, in situ DRIFTS and DFT calculations show that the pyridinic-N/B-N FLPs sites can efficiently activate the C═O of aldehydes and H2 molecules with only 0.53 eV dissociation energy of the H-H bond. Also, the catalyst presents excellent catalytic performance in the transfer hydrogenation reactions with cyclohexanol and its derivatives as hydrogen sources. This study provides new ideas for the design and preparation of all-solid-state FLPs metal-free catalysts and promotes the green synthesis of unsaturated alcohols.

Two-Dimensional Catalysts: From Model to Reality

Two-dimensional (2D) materials have been utilized broadly in kinds of catalytic reactions due to their fully exposed active sites and special electronic structure. Compared with real catalysts, which are usually bulk or particle, 2D materials have more well-defined structures. With easily identified structure-modulated engineering, 2D materials become ideal models to figure out the catalytic structure-function relations, which is helpful for the precise design of catalysts. In this review, the unique function of 2D materials was summarized from model study to reality catalysis and application. It includes several typical 2D materials, such as graphene, transition metal dichalcogenides, metal, and metal (hydr)oxide materials. We introduced the structural characteristics of 2D materials and their advantages in model researches. It emphatically summarized how 2D materials serve as models to explore the structure-activity relationship by combining theoretical calculations and surface research. The opportunities of 2D materials and the challenges for fundamentals and applications they facing are also addressed. This review provides a reference for the design of catalyst structure and composition, and could inspire the realization of two-dimensional materials from model study to reality application in industry.

Novel Inorganic-Organic Dual-Photosensitizing Dinuclear-Metal Self-Assembly System for Efficient Artificial Photosynthesis without Sacrificial Electron Donors

Owing to the unique synergistic effect, dinuclear-metal-molecule-catalysts (DMCs) show excellent performance in catalytic fields. However, for overall photocatalytic CO2 reaction (CO2RR), it is still a challenge to construct well-matched photosensitizer (PS) components for DMCs-based photocatalysts. Inorganic-quantum-dot PS possesses capacities of multiple exciton generation and catalyzing water oxidation but is incompatible with DMCs. In contrast, organic PS can be covalently linked with DMCs but inescapable of using sacrificial electron donors. For overall photocatalytic CO2RR, organic-inorganic dual-photosensitizing system might be a promising candidate. Herein, we employed covalent-linking and electrostatic-driven approaches to construct the self-assembly of pyrene-sensitized Co2L DMCs (Py-Co2L) and perovskite (PVK) quantum dots, i.e., PVK@[Py-Co2L]. Using H2O as an electron donor, PVK@[Py-Co2L] realized 105.24 μmol ⋅ g-1⋅h-1 CO yield in photocatalytic CO2RR, much higher than PVK (15.44 μmol ⋅ g-1⋅h-1) and PVK@Co2L (32.30 μmol ⋅ g-1 ⋅ h-1), ascribing to the efficient photogenerated charge separation and transfer. The experimental results and theoretical investigations demonstrated that the pyrene linked on Co2L boosted the electron delivery from PVK to DMCs. Besides, this strategy could also be extended to the photocatalytic H2 evolution coupled with alcohol oxidation. As a proof-of-concept, our work lightens the integration of DMCs, organic and inorganic PS components, promoting the development of photocatalysis without sacrificial electron donors.

Structural Control of Photoconductivity in a Flexible Titanium-Organic Framework

The soft nature of Metal-Organic Frameworks (MOFs) sets them apart from other non-synthetic porous materials. Their flexibility allows the framework components to rearrange in response to environmental changes, leading to different states and properties. The work extends this concept to titanium frameworks, demonstrating control over charge transport in porous molecular crystals. MUV-35 is a two-fold catenated framework composed of heterometallic TiMn2 trimers and electron donor 4,4',4″-(benzo[1,2-b:3,4-b':5,6-b″]trithiophene-2,5,8-triyl)tribenzoic acid (H3BTTTB) linkers, forming a rare sit-c net topology that can fold to reduce its volume by ≈40% through a single-crystal transformation controlled by linker conformation in open, intermediate, and closed states. This process, driven by a free energy difference of ≈300 kJ mol-1, originates from the formation of a continuous network of non-covalent interactions that force the spontaneous loss of the solvent in the pores of the framework to establish charge transport pathways that afford photocurrents of 2.5 × 10-3 S m-1 under visible light for an ON/OFF ratio (∆R) of four orders of magnitude. This photoconductivity rivals the best conductivity values described for though-transport conductive MOFs while maintaining a porosity of ≈1.000 m2 g-1.

Host molecules inside metal-organic frameworks: host@MOF and guest@host@MOF (Matrjoschka) materials

The controllable encapsulation of host molecules (such as porphyrin, phthalocyanine, crown ether, calixarene or cucurbituril organic macrocycles, cages, metal-organic polyhedrons and enzymes) into the pores of metal-organic frameworks (MOFs) to form host-in-host (host@MOF) materials has attracted increasing research interest in various fields. These host@MOF materials combine the merits of MOFs as a host matrix and functional host molecules to exhibit synergistic functionalities for the formation of guest@host@MOF materials in sorption and separation, ion capture, catalysis, proton/ion conduction and biosensors. (This guest@host@MOF construction is reminiscent of Russian (Matrjoschka) dolls which are nested dolls of decreasing size placed one inside another.) In this tutorial review, the advantages of MOFs as a host matrix are presented; the encapsulation approaches and general important considerations for the preparation of host@MOF materials are introduced. The state-of-the-art examples of these materials based on different host molecules are shown, and representative applications and general characterization of these materials are discussed. This review will guide researchers attempting to design functional host@MOF and guest@host@MOF materials for various applications.

Unlocking the catalytic potential of heterogeneous nonprecious metals for selective hydrogenation reactions

Selective hydrogenation has been employed extensively to produce value-added chemicals and fuels, greatly alleviating the problems of fossil resources and green synthesis. However, the design and synthesis of highly efficient catalysts, especially those that are inexpensive and abundant in the earth's crust, is still required for basic research and subsequent industrial applications. In recent years, many studies have revealed that the rational design and synthesis of heterogeneous catalysts can efficaciously improve the catalytic performance of hydrogenation reactions. However, the relationship between nonprecious metal catalysts and hydrogenation performance from the perspective of different catalytic systems still remains to be understood. In this review, we provide a comprehensive and systematic overview of the recent advances in the synthesis of nonprecious metal catalysts for heterogeneous selective hydrogenation reactions including thermocatalytic hydrogenation/transfer hydrogenation, photocatalytic hydrogenation and electrocatalytic reduction. In addition, we also aim to provide a clear picture of the recent design strategies and proposals for the nonprecious metal catalysed hydrogenation reactions. Finally, we discuss the current challenges and future research opportunities for the precise design and synthesis of nonprecious metal catalysts for selective hydrogenation reactions.

Cooperative Brønsted Acid-Single Atom Photocatalysis in Metal-Organic Framework

Enzymes, composed of earth-abundant elements, outperform conventional heterogeneous photocatalysts in hydrogen production due to the dual-site cooperation between adjacent active metal sites and proton-transferring ligands. However, the realization of such dual-site cooperation in heterogeneous catalytic systems is hindered by the challenges in the precise construction of cooperative active sites. In this study, we present the design of a structurally tuned metal-organic framework (MOF) photocatalyst that incorporates cooperative Brønsted acid-single atom catalytic sites. By grafting Co single-atom sites onto the Ti-oxo clusters and introducing Brønsted acidic P-OH moieties in tandem within the MOF-based catalyst structure, we achieved a visible-light-activated photocatalytic H2 production rate of 6.6 mmol g-1 h-1, which is 6.6 times higher than that of a Pt nanoparticle-based cocatalyst, emphasizing the significance of incorporating cooperative Brønsted acid-single atom catalytic sites.

High-Entropy Ag-Ru-Based Electrocatalysts with Dual-Active-Center for Highly Stable Ultra-Low-Temperature Zinc-Air Batteries

The development of advanced bifunctional catalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is significant for rechargeable zinc-air batteries (ZABs). Herein, a unique dual active center alloying strategy is proposed to achieve the efficient bifunctional oxygen catalysis, and the high entropy effect is further exploited to modulate the structure and performance of the catalysts. The MOF-assisted pyrolysis-replacement-alloying method was employed to construct the CoCuFeAgRu high-entropy alloy (HEA), which are uniformly anchored in porous nitrogen-doped carbon nanosheets. Notably, the obtained HEA catalyst exhibits excellent catalytic performance for both ORR and OER, and a peak power density of 136. 53 mW cm-2 and an energy density of 987.9 mAh gZn -1, surpassing the most of the previously reported bifunctional oxygen electrocatalysts. Moreover, the assembled flexible rechargeable ZAB enables excellent performance even at the ultralow temperature of -40 °C, with an energy density of 601.6 mAh gZn -1 and remarkable cycling stability up to 1,650 hours. Combined experimental and theoretical calculation results reveal that the excellent bifunctional catalytic activity of the HEA catalyst originated from the synergistic effect of the Ag and Ru dual active centers, and the optimization of the electronic structure by alloying effect.

Integration of metal-organic frameworks and clay toward functional composite materials

Metal-organic frameworks (MOFs) have become increasingly important as a class of porous crystalline materials because of their diverse applications. At the same time, significant progress has been achieved in the field of MOF-based composite materials toward novel applications based on the synergistic effect of two or more different components. Clay materials have been explored recently in MOF chemistry for the synthesis of MOF-clay composites, which are a new class of functional materials synthesized by a cooperative combination of MOFs with clay. Such composites have evolved only in the recent past with important functions and applications, such as enhanced gas storage and separation, CO2 capture and conversion, catalysis, drug delivery, and water harvesting. Notably, the typical shortcomings of MOFs, such as moisture sensitivity, poor water dispersibility, poor thermal and chemical stability, and poor processability, could be overcome by developing novel MOF-clay composites. This article provides a concise overview of MOF-clay composites and their applications in various fields that will drive the interest of researchers to explore the emerging field of MOF-clay chemistry. In the initial sections, we classify the clays that have been used in MOF chemistry and briefly discuss their structures and chemistry. We also present the advantages of MOF-clay composites and discuss their synthetic methodologies. In the later sections, we classify different MOF-clay composites based on the clay and present some representative examples of such composites that show unique properties and applications. Finally, the development in this field is summarized, and the future scope of such composites is discussed.

Zr-MOFs (UIO-66-NH2)@Fluorinated Graphene for Developing Highly Antiwear, Friction-Reduction Lubricating Additives

Fluorinated graphene (FG) among numerous two-dimensional materials has enormous potential in improving antifriction properties. However, they being susceptible to thermal oxidation and prone to wear hinder practical applications. Herein, UIO-66-NH2 (Zr-MOF) enjoying good chemical and thermal stabilities was assembled on the surface of FG nanosheets under covalent bonds and van der Waals forces. The Zr-MOF@FG composite was successfully synthesized and used as a lubricant additive. It can be seen that Zr-MOF@FG composites offer a synergistic lubricant mechanism at the friction interface. Moreover, due to the adsorption and purification performance of Zr-MOF, the obtained Zr-MOF@FG composite adsorbs the abrasive rust during the friction process, thereby realizing the purification of the lubricant. These findings suggest that Zr-MOF@FG shows tremendous potential as a lubricant additive.

Hybrid Metal-Organic Frameworks (MOFs) for Various Catalysis Applications

Porous materials have been gaining popularity in catalysis applications, solving the current ecological challenges. Metal-organic frameworks (MOFs) are especially noteworthy for their high surface areas and customizable chemistry, giving them a wide range of potential applications in catalysis remediation. The review study delves into the various applications of MOFs in catalysis and provides a comprehensive summary. This review thoroughly explores MOF materials, specifically focusing on their diverse catalytic applications, including Lewis catalysis, oxidation, reduction, photocatalysis, and electrocatalysis. Also, this study emphasizes the significance of high-performance MOF materials, which possess adjustable properties and exceptional features, as a novel approach to tackling technological challenges across multiple sectors. MOFs make it an ideal candidate for catalytic reactions, as it enables efficient conversion rates and selectivity. Furthermore, the tunable properties of MOF make it possible to tailor its structure to suit specific catalytic requirements. This feature improves performance and reduces costs associated with traditional catalysts. In conclusion, MOF materials have revolutionized the field of catalysis and offer immense potential in solving various technological challenges across different industries.

Modifications and Applications of Metal-Organic-Framework-Based Materials for Photocatalysis

Metal-organic frameworks (MOFs) represent a category of crystalline materials formed by the combination of metal ions or clusters with organic linkers, which have emerged as a prominent research focus in the field of photocatalysis. Owing to their distinctive characteristics, including structural diversity and configurations, significant porosity, and an extensive specific surface area, they provide a flexible foundation for various potential applications in photocatalysis. In recent years, researchers have tackled many issues in the MOF-based photocatalytic yield. However, limited light adsorption regions, lack of active sites and active species, and insufficient efficiency of photogenerated charge carrier separation substantially hinder the photocatalytic performance. In this review, we summarized the strategies to improve the photocatalytic performance and recent developments achieved in MOF and MOF-based photocatalysis, including water splitting, CO2 conversion, photocatalytic degradation of pollutants, and photocatalytic nitrogen fixation into ammonia. In conclusion, the existing challenges and prospective advancements in MOF-based photocatalysis are also discussed.

Integrating Compositional and Structural Diversity in Heterometallic Titanium Frameworks by Metal Exchange Methods

The increasing use of Metal-Organic Frameworks (MOFs) in separation, catalysis, or storage is linked to the targeted modification of their composition or porosity metrics. While modification of pore shape and size necessarily implies the assembly of alternative nets, compositional changes often rely on postsynthetic modification adapted to the functionalization or exchange of the organic linker or the modification of the inorganic cluster by metal exchange methods. We describe an alternative methodology that enables the integration of both types of modification, structural and compositional, in titanium MOFs by metal exchange reaction of the heterometallic cluster Ti2Ca2. A systematic analysis of this reactivity with MUV-10 is used to understand which experimental variables are crucial to enable replacement of calcium only or to integrate metal exchange with structural transformation. The isoreticular expanded framework, MUV-30, is next used to template the formation of MUV-301, a titanium framework not accessible by direct synthesis that displays the largest mesoporous cages reported to date. Given that the interest of Ti MOFs in photoredox applications often meets the limitations imposed by the challenges of titanium solution chemistry to design concrete candidates, this soft strategy based on preassembled frameworks will help integrate specific combinations of metals into high porosity architectures.

Incorporation of enzyme-mimic species in porous materials for the construction of porous biomimetic catalysts

The unique catalytic properties of natural enzymes have inspired chemists to develop biomimetic catalyst platforms for the intention of retaining the unique functions and solving the application limitations of enzymes, such as high costs, instability and unrecyclable ability. Porous materials possess unique advantages for the construction of biomimetic catalysts, such as high surface areas, thermal stability, permanent porosity and tunability. These characteristics make them ideal porous matrices for the construction of biomimetic catalysts by immobilizing enzyme-mimic active sites inside porous materials. The developed porous biomimetic catalysts demonstrate high activity, selectivity and stability. In this feature article, we categorize and discuss the recently developed strategies for introducing enzyme-mimic active species inside porous materials, which are based on the type of employed porous materials, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), molecular sieves, porous metal silicate (PMS) materials and porous carbon materials. The advantages and limitations of these porous materials-based biomimetic catalysts are discussed, and the challenges and future directions in this field are also highlighted.

Immobilization of Metal Nanoparticles to an Ultrathin Two-Dimensional Conjugated Metal-Organic Framework for Synergistic Electrocatalysis

Metal-organic frameworks (MOFs) have been considered as promising hosts for immobilizing ultrafine metal nanoparticles (MNPs) due to their high surface area and porosity. However, electrochemical applications of such emerging composites are severely limited by the poor electrical conductivity and large size of the MOFs. Herein, we report the general synthesis of incorporating various MNPs into a conjugated MOF ultrathin nanosheet (Cu-TCPP UNS) matrix, which not only prevents agglomeration and restricts the growth of MNPs but also benefits the exposure of active sites and the transport of electrons. Specifically, the obtained PtCu@Cu-TCPP UNSs exhibited nearly two times higher mass activity for the methanol oxidation reaction (MOR) than the commercial Pt/C catalyst. Mechanistic studies reveal that the strong interaction between MNPs and Cu-TCPP promotes the oxidation of the CO intermediate. Moreover, the PtCu@Cu-TCPP UNSs can be employed as bifunctional electrocatalysts to couple MOR with the hydrogen evolution reaction for highly efficient hydrogen production.

Supporting Nano Catalysts for the Selective Hydrogenation of Biomass-derived Compounds

The selective hydrogenation of biomass derivatives presents a promising pathway for the production of high-value chemicals and fuels, thereby reducing reliance on traditional petrochemical industries. Recent strides in catalyst nanostructure engineering, achieved through tailored support properties, have significantly enhanced the hydrogenation performance in biomass upgrading. A comprehensive understanding of biomass selective upgrading reactions and the current advancement in supported catalysts is crucial for guiding future processes in renewable biomass. This review aims to summarize the development of supported nanocatalysts for the selective hydrogenation of the US DOE's biomass platform compounds derivatives into valuable upgraded molecules. The discussion includes an exploration of the reaction mechanisms and conditions in catalytic transfer hydrogenation (CTH) and high-pressure hydrogenation. By thoroughly examining the tailoring of supports, such as metal oxide catalysts and porous materials, in nano-supported catalysts, we elucidate the promoting role of nanostructure engineering in biomass hydrogenation. This endeavor seeks to establish a robust theoretical foundation for the fabrication of highly efficient catalysts. Furthermore, the review proposes prospects in the field of biomass utilization and address application bottlenecks and industrial challenges associated with the large-scale utilization of biomass.

Exploring enzyme-immobilized MOFs and their application potential: biosensing, biocatalysis, targeted drug delivery and cancer therapy

Enzymes are indispensable in several applications including biosensing and degradation of pollutants and in the drug industry. However, adverse conditions restrict enzymes' utility in biocatalysis due to their inherent limitations. Metal-organic frameworks (MOFs), with their robust structure, offer an innovative avenue for enzyme immobilization, enhancing their resilience against harsh solvents and temperatures. This advancement is pivotal for application in bio-sensing, bio-catalysis, and specifically, targeted drug delivery in cancer therapy, where enzyme-MOF composites enable precise therapeutic localization, minimizing the side effects of traditional treatment. The adaptable nature of MOFs enhances drug biocompatibility and availability, significantly improving therapeutic outcomes. Moreover, the integration of enzyme-immobilized MOFs into bio-sensing represents a leap forward in the rapid and accurate identification of biomarkers, facilitating early diagnosis and disease monitoring. In bio-catalysis, this synergy promotes efficient and environmentally safe chemical synthesis, enhancing reaction rates and yields and broadening the scope of enzyme application in pharmaceutical and bio-fuel production. This review article explores the immobilization techniques and their biomedical applications, specifically focusing on drug delivery in cancer therapy and bio-sensing. Additionally, it addresses the challenges faced in this expanding field.

Leveraging Ligand Steric Demand to Control Ligand Exchange and Domain Composition in Stratified Metal-Organic Frameworks

Incorporating diverse components into metal-organic frameworks (MOFs) can expand their scope of properties and applications. Stratified MOFs (sMOFs) consist of compositionally unique concentric domains (strata), offering unprecedented complexity through partitioning of structural and functional components. However, the labile nature of metal-ligand coordination handicaps achieving compositionally distinct domains due to ligand exchange reactions occurring concurrently with secondary strata growth. To achieve complex sMOF compositions, characterizing and controlling the competing processes of new strata growth and ligand exchange are vital. This work systematically examines controlling ligand exchange in UiO-67 sMOFs by tuning ligand sterics. We present quantitative methods for assessing and visualizing the outcomes of strata growth and ligand exchange that rely on high-angle annular dark-field images and elemental mapping via scanning transmission electron microscopy-energy dispersive X-ray spectroscopy. In addition, we leverage ligand sterics to create 'blocking layers' that minimize ligand exchange between strata which are particularly susceptible to ligand exchange and inter-strata ligand mixing. Finally, we evaluate strata compositional integrity in various solvents and find that sMOFs can maintain their compositions for >12 months in some cases. Collectively, these studies and methods enhance understanding and control over ligand placement in multi-domain MOFs, factors that underscore careful tunning of properties and function.

Controlling nanocluster growth through nanoconfinement: the effect of the number and nature of metal-organic framework functionalities

Controlled nanocluster growth via nanoconfinement is an attractive approach as it allows for geometry control and potential surface-chemistry modification simultaneously. However, it is still not a straight-forward method and much of its success depends on the nature and possibly concentration of functionalities on the cavity walls that surround the clusters. To independently probe the effect of the nature and number of functional groups on the controlled Pd nanocluster growth within the pores of the metal-organic frameworks, Pd-laden UiO-66 analogues with mono- and bi-functionalised linkers of amino and methyl groups were successfully prepared and studied in a combined experimental-computational approach. The nature of the functional groups determines the strength of host-guest interactions, while the number of functional groups affects the extent of Pd loading. The interplay of these two effects means that for a successful Pd embedding, mono-functionalised host matrices are more favourable. Interestingly, in the context of the present and previous research, we find that host frameworks with functional groups displaying higher Lewis basicity are more successful at controlled Pd NC growth via nanoconfinement in MOFs.

Solar Energy-Driven Reverse Water Gas Shift Reaction: Photothermal Effect, Photoelectric Activation and Selectivity Regulation

Excessive carbon dioxide (CO2) emissions are one of the main causes of the greenhouse effect. Thermal catalytic reverse water gas shift (RWGS) reaction, which is a pre reaction for Fischer-Tropsch synthesis, is considered an effective way to convert CO2 and synthesize high value-added chemicals in industry. However, traditional thermal catalysis requires a large amount of fossil fuels to drive reactions, which cannot achieve the true goal of carbon neutrality. Photothermal catalysis, as a novel conversion pathway, can achieve efficient CO2 conversion while significantly improving solar energy utilization. This review provides a detailed introduction of CO2 and H2 adsorption/activation and reaction pathways in thermal catalysis, as well as the catalytic mechanisms of thermal and chemical effects in photothermal catalytic RWGS to supply readers valuable insights on the mechanism of photothermal catalytic RWGS reaction and provide a reference for better catalyst design.

Electron beam and thermal stabilities of MFM-300(M) metal-organic frameworks

This work reports the thermal and electron beam stabilities of a series of isostructural metal-organic frameworks (MOFs) of type MFM-300(M) (M = Al, Ga, In, Cr). MFM-300(Cr) was most stable under the electron beam, having an unusually high critical electron fluence of 1111 e- Å-2 while the Group 13 element MOFs were found to be less stable. Within Group 13, MFM-300(Al) had the highest critical electron fluence of 330 e- Å-2, compared to 189 e- Å-2 and 147 e- Å-2 for the Ga and In MOFs, respectively. For all four MOFs, electron beam-induced structural degradation was independent of crystal size and was highly anisotropic, although both the length and width of the channels decreased during electron beam irradiation. Notably, MFM-300(Cr) was found to retain crystallinity while shrinking up to 10%. Thermal stability was studied using in situ synchrotron X-ray diffraction at elevated temperature, which revealed critical temperatures for crystal degradation to be 605, 570, 490 and 480 °C for Al, Cr, Ga, and In, respectively. The pore channel diameters contracted by ≈0.5% on desorption of solvent species, but thermal degradation at higher temperatures was isotropic. The observed electron stabilities were found to scale with the relative inertness of the cations and correlate well to the measured lifetime of the materials when used as photocatalysts.

Hydrophobic Microenvironment Modulation of Ru Nanoparticles in Metal-Organic Frameworks for Enhanced Electrocatalytic N2 Reduction

The modulation of the chemical microenvironment surrounding metal nanoparticles (NPs) is an effective means to enhance the selectivity and activity of catalytic reactions. Herein, a post-synthetic modification strategy is developed to modulate the hydrophobic microenvironment of Ru nanoparticles encapsulated in a metal-organic framework (MOF), MIP-206, namely Ru@MIP-Fx (where x represents perfluoroalkyl chain lengths of 3, 5, 7, 11, and 15), in order to systematically explore the effect of the hydrophobic microenvironment on the electrocatalytic activity. The increase of perfluoroalkyl chain length can gradually enhance the hydrophobicity of the catalyst, which effectively suppresses the competitive hydrogen evolution reaction (HER). Moreover, the electrocatalytic production rate of ammonia and the corresponding Faraday efficiency display a volcano-like pattern with increasing hydrophobicity, with Ru@MIP-F7 showing the highest activity. Theoretical calculations and experiments jointly show that modification of perfluoroalkyl chains of different lengths on MIP-206 modulates the electronic state of Ru nanoparticles and reduces the rate-determining step for the formation of the key intermediate of N2H2 *, leading to superior electrocatalytic performance.

MOFs-Based Materials with Confined Space: Opportunities and Challenges for Energy and Catalytic Conversion

Metal-Organic Frameworks (MOFs) are a very promising material in the fields of energy and catalysis due to their rich active sites, tunable pore size, structural adaptability, and high specific surface area. The concepts of "carbon peak" and "carbon neutrality" have opened up huge development opportunities in the fields of energy storage, energy conversion, and catalysis, and have made significant progress and breakthroughs. In recent years, people have shown great interest in the development of MOFs materials and their applications in the above research fields. This review introduces the design strategies and latest progress of MOFs are included based on their structures such as core-shell, yolk-shell, multi-shelled, sandwich structures, unique crystal surface exposures, and MOF-derived nanomaterials in detail. This work comprehensively and systematically reviews the applications of MOF-based materials in energy and catalysis and reviews the research progress of MOF materials for atmospheric water harvesting, seawater uranium extraction, and triboelectric nanogenerators. Finally, this review looks forward to the challenges and opportunities of controlling the synthesis of MOFs through low-cost, improved conductivity, high-temperature heat resistance, and integration with machine learning. This review provides useful references for promoting the application of MOFs-based materials in the aforementioned fields.

Design of hollow structured nanoreactors for liquid-phase hydrogenations

Inspired by the attractive structures and functions of natural matter (such as cells, organelles and enzymes), chemists are constantly exploring innovative material platforms to mimic natural catalytic systems, particularly liquid-phase hydrogenations, which are of great significance for chemical upgrading and synthesis. Hollow structured nanoreactors (HSNRs), featuring unique nanoarchitectures and advantageous properties, offer new opportunities for achieving excellent catalytic activity, selectivity, stability and sustainability. Notwithstanding the great progress made in HSNRs, there still remain the challenges of precise synthetic chemistry, and mesoscale catalytic kinetic investigation, and smart catalysis. To this extent, we provide an overview of recent developments in the synthetic chemistry of HSNRs, the unique characteristics of these materials and catalytic mechanisms in HSNRs. Finally, a brief outlook, challenges and further opportunities for their synthetic methodologies and catalytic application are discussed. This review might promote the creation of further HSNRs, realize the sustainable production of fine chemicals and pharmaceuticals, and contribute to the development of materials science.

Mussel-inspired interface deposition strategy for mesoporous metal-phenolic nanospheres with superior antioxidative, photothermal and antibacterial performance

Metal-phenolic networks (MPNs) have emerged as a versatile and multifunctional platform applied in bioimaging, disease treatment, electrocatalysis, and water purification. The synthesis of MPNs with mesoporous frameworks and ultra-small diameters (<200 nm), crucial for post-modification, cargo loading, and mass transport, remains a formidable challenge. Inspired by mussel chemistry, mesoporous metal-phenolic nanospheres (MMPNs) are facilely prepared by direct deposition of the metal-polyphenol complex on the interface of oil nano-droplets composed of block copolymers/1,3,5-trimethylbenzene followed by a spontaneous template-removal process. Due to the penetrable and stable networks, the oil nano-droplets gradually leak from the networks driven by shear stress during the stirring process. As a result, MMPNs are obtained without additional template removal procedures such as solvent extraction or high-temperature calcination. The materials have a large pore size (∼12.1 nm), uniform spherical morphology with a small particle size (∼99 nm), and a large specific surface area (49.8 m2 g-1). Due to the abundant phenolic hydroxyl groups, the MMPNs show excellent antioxidative property. The MMPNs also have excellent photothermal property, whose photothermal conversion efficiency was 40.9 %. Moreover, the phenolic hydroxyl groups can reduce Ag+ in situ to prepare Ag nanoparticles loaded MMPNs composites, which have excellent inhibition performance of drug-resistant bacteria biofilm.

Anchoring Ultrafine β-Mo2C Clusters Inside Porous Co-NC Using MOFs for Electric-Powered Coproduction of Valuable Chemicals

Electroredox of organics provides a promising and green approach to producing value-added chemicals. However, it remains a grand challenge to achieve high selectivity of desired products simultaneously at two electrodes, especially for non-isoelectronic transfer reactions. Here a porous heterostructure of Mo2C@Co-NC is successfully fabricated, where subnanometre β-Mo2C clusters (<1 nm, ≈10 wt%) are confined inside porous Co, N-doped carbon using metalorganic frameworks. It is found that Co species not only promote the formation of β-Mo2C but also can prevent it from oxidation by constructing the heterojunctions. As noted, the heterostructure achieves >96% yield and 92% Faradaic efficiency (FE) for aldehydes in anodic alcohol oxidation, as well as >99.9% yield and 96% FE for amines in cathodal nitrocompounds reduction in 1.0 M KOH. Precise control of the reaction kinetics of two half-reactions by the electronic interaction between β-Mo2C and Co is a crucial adjective. Density functional theory (DFT) gives in-depth mechanistic insight into the high aldehyde selectivity. The work guides authors to reveal the electrooxidation nature of Mo2C at a subnanometer level. It is anticipated that the strategy will provide new insights into the design of highly effective bifunctional electrocatalysts for the coproduction of more complex fine chemicals.

Regulating Second-Shell Coordination in Cobalt Single-Atom Catalysts toward Highly Selective Hydrogenation

Manipulating the local coordination environment of central metal atoms in single-atom catalysts (SACs) is a powerful strategy to exploit efficient SACs with optimal electronic structures for various applications. Herein, Co-SACs featured by Co single atoms with coordinating S atoms in the second shell dispersed in a nitrogen-doped carbon matrix have been developed toward the selective hydrogenation of halo-nitrobenzene. The location of the S atom in the model Co-SAC is verified through synchrotron-based X-ray absorption spectroscopy and theoretical calculations. The resultant Co-SACs containing second-coordination shell S atoms demonstrate excellent activity and outstanding durability for selective hydrogenation, superior to most precious metal-based catalysts. In situ characterizations and theoretical results verify that high activity and selectivity are attributed to the advantageous formation of the Co-O bond between p-chloronitrobenzene and Co atom at Co1N4-S moieties and the lower free energy and energy barriers of the reaction. Our findings unveil the correlation between the performance and second-shell coordination atom of SACs.

Enabling long-distance hydrogen spillover in nonreducible metal-organic frameworks for catalytic reaction

Hydrogen spillover is an extraordinary effect in heterogeneous catalysis and hydrogen storage, which refers to the surface migration of metal particle-activated hydrogen atoms over the solid supports. Historical studies on this phenomenon have mostly been limited to reducible metal oxides where the long-distance proton-electron coupled migration mechanism has been established, yet the key question remains on how to surmount short-distance and defect-dependent hydrogen migration on nonreducible supports. By demerging hydrogen migration and hydrogenation reaction, here we demonstrate that the hydrogen spillover in nonreducible metal-organic frameworks (MOFs) can be finely modulated by the ligand functional groups or embedded water molecules, enabling significant long-distance (exceed 50 nm) movement of activated hydrogen. Furthermore, using sandwich nanostructured MOFs@Pt@MOFs as catalysts, we achieve highly selective hydrogenation of N-heteroarenes via controllable hydrogen spillover from Pt to MOFs-shell. We anticipate that this work will enhance the understanding of hydrogen spillover and shed light on de novo design of MOFs supported catalysts for many important reactions involving hydrogen.

Hybrid Mn Atomic Clusters/Single-Dispersed Atoms with Dual Antioxidant Activities for a Chemiluminescent Immunoassay

Single-dispersed atoms (SDAs) as catalysts have drawn extensive attention due to their ultimate atom utilization efficiency and desirable catalytic capability. Atomic clusters (ACs) with potential multiple enzyme-like activities also display great practicability in catalysis-based biosensing. In this work, hybrid Mn ACs/SDAs were implanted in the frameworks of defect-engineered MIL 101(Cr) modulated by excess acetic acid, with a high loading capability of 13.9 wt %. Distinctively, Mn SDAs display weak superoxide dismutase (SOD)-like activity for specifically eliminating superoxide anion (O2•-), while Mn ACs/SDAs display both catalase-like and SOD-like activities for remarkable elimination of total reactive oxygen species (ROS) due to the cooperative effect of the two atom-scale catalytic sites. Thus, Mn ACs/SDAs can efficiently inhibit the chemiluminescent (CL) emission of multiple ROS-mediated luminol systems with a superior quenching rate of 85.5%. To validate the practicability of Mn ACs/SDAs for a sensitive CL assay, an immunoassay method was established to detect acetamiprid by using Mn ACs/SDAs as signal quenchers, which displayed a quantification range of 10 pg mL-1-25 ng mL-1 and a detection limit of 3.3 pg mL-1. This study paves an avenue for developing ACs/SDAs with multiple antioxidant activities that are suitable for application in biosensing.