Electronic State and Microenvironment Modulation of Metal Nanoparticles Stabilized by MOFs for Boosting Electrocatalytic Nitrogen Reduction

Tuning Metal-Phthalocyanine 2D Covalent Organic Frameworks for the Nitrogen Reduction Reaction: Cooperativity of Transition Metals and Organic Linkers

Two-dimensional covalent organic frameworks (2D-COFs) exhibit high activity in the electrochemical nitrogen reduction reaction (NRR), while the structure-performance relationship toward which remains an unsolved problem, therefore hindering the development of efficient catalysts. In this work, a total of 145 candidate transition metal phthalocyanine (TMPc-DX) materials comprised of 29 transition metals and X-phthalocyanine (X = N, O, F, S, and Cl) are evaluated for their capabilities in the NRR by density functional theory calculations. Our computations showed that metal atoms in TMPc-DN/DF/DCl materials could efficiently activate N2 molecules by doping with electron-withdrawing groups. The catalysts MoPc-DN and NbPc-DN are recognized to exhibit the highest electrocatalytic performance for the NRR with the lowest limit potentials of 0.31 and 0.32 V, respectively. Moreover, NbPc-DN showed a significant advantage by suppressing the hydrogen evolution reaction, making it a top contender among TMPc-DX materials for the electrocatalytic NRR. Through detailed orbital interaction analysis, our research has demonstrated that embedding transition metals into the substrate (Pc-DX) results in a direct correlation between the number of electrons transferred to the substrate and the reduction of energy splitting of the metal's d orbital, which directly causes a decrease in the metal's magnetic moment. Consequently, the affinity of the metal for N2 adsorption is directly proportional to the extent of the electron transfer. Our findings underscore the significance of the material's magnetic moment as a preliminary indicator for gauging the effectiveness of N2 adsorption.

Microenvironment modulation of two-dimensional defective carbon nitride with extended nanoporous furnished oxygen-enriched sites for efficient recovery of rare earth elements

Efficient recovery of rare earth elements (REEs) from wastewater is crucial for environmental remediation and the sustainable development of resources. Nevertheless, achieving efficient and selective REEs extraction in the systems containing low-concentration REEs and high-concentration competing metal ions remains a challenge. Here, we report on the fabrication of two-dimensional defective carbon nitride (DGCN-K) with extended nanoporous furnished oxygen-enriched sites, which is achieved through re-arrangement of framework structural unit using a flexible polycondensation-ion-thermal strategy. The extended nanoporous and continuous transmission nanochannels establish a dedicated structure microenvironment surrounding the active sites center, promoting the effective ion diffusion and increasing the accessibility of active sites. Meanwhile, the incorporation of abundant electronegative cyano and hydroxyl group modifies coordination microenvironment, improving hydrophilicity and strengthening interaction affinity with REEs. Consequently, DGCN-K shows excellent REEs adsorption performance, achieving high adsorption capacity (Nd(III) 146.25 mg/g, Dy(III) 180.82 mg/g, Lu(III) 204.34 mg/g,) within short adsorption equilibrium time (30 min). Furthermore, DGCN-K possesses high REEs selective removal rate in the mixed binary system and actual leaching tailings. This study provides a feasible microenvironment regulation strategy for the construction of 2D defective carbon nitride with oxygen-enriched sites and extended nanoporous for synergistically enabling efficient recovery of REEs.

Interfacial Engineering to Fabricate Nanoporous FeMo Bimetallic Nitride for Enhanced Electrochemical Ammonia Synthesis

The electrochemical N2 reduction reaction (NRR) currently represents a green and sustainable approach to ammonia production. However, the further progress of NRR is significantly hampered by poor catalytic activity and selectivity, necessitating the development of efficient and stable electrocatalysts. Herein, a nanoporous Fe-Mo bimetallic nitride (Fe3N-MoN) is synthesized using a molten-salt preparation method. This catalyst demonstrates notable NRR performance, achieving a high NH3 yield rate of 45.1 µg h-1 mg-1 and a Faradaic efficiency (FE) of 26.5% at -0.2 V (vs RHE) under ambient conditions. Detailed experimental studies and density functional theory (DFT) calculations reveal that the fabricated interface between Fe3N and MoN effectively modulates the surface electronic structure of the catalyst. The interface induces an increase in the degree of electron deficiency at the nitrogen-vacancy sites on the catalyst surface, allowing N2 molecules to occupy the nitrogen vacancies more easily, thereby promoting N2 adsorption/activation during the NRR process. Consequently, the Fe3N-MoN catalyst exhibits outstanding NRR activity. The insights gained from fabricating the Fe3N-MoN interface in this work pave the way for further development of interfacial engineering to prepare high-efficient electrocatalyst.

Defect Engineering of Metal-Based Atomically Thin Materials for Catalyzing Small-Molecule Conversion Reactions

Recently, metal-based atomically thin materials (M-ATMs) have experienced rapid development due to their large specific surface areas, abundant electrochemically accessible sites, attractive surface chemistry, and strong in-plane chemical bonds. These characteristics make them highly desirable for energy-related conversion reactions. However, the insufficient active sites and slow reaction kinetics leading to unsatisfactory electrocatalytic performance limited their commercial application. To address these issues, defect engineering of M-ATMs has emerged to increase the active sites, modify the electronic structure, and enhance the catalytic reactivity and stability. This review provides a comprehensive summary of defect engineering strategies for M-ATM nanostructures, including vacancy creation, heteroatom doping, amorphous phase/grain boundary generation, and heterointerface construction. Introducing recent advancements in the application of M-ATMs in electrochemical small molecule conversion reactions (e.g., hydrogen, oxygen, carbon dioxide, nitrogen, and sulfur), which can contribute to a circular economy by recycling molecules like H2, O2, CO2, N2, and S. Furthermore, a crucial link between the reconstruction of atomic-level structure and catalytic activity via analyzing the dynamic evolution of M-ATMs during the reaction process is established. The review also outlines the challenges and prospects associated with M-ATM-based catalysts to inspire further research efforts in developing high-performance M-ATMs.

Self-Polycondensation Flux Synthesis of Ultrastable Olefin-Linked Covalent Organic Frameworks for Electrocatalysis

Creating new functional materials that efficiently support noble metal catalysts is important and in high demand. Herein, we develop a self-polycondensation flux synthesis strategy that can produce olefin-linked covalent organic framework (COF) platforms with high crystallinity and porosity as the supports of Pd nanoparticles for electrocatalytic nitrogen reduction reaction (ENRR). A series of "two in one" monomers integrating aldehyde and methyl reactive groups are rationally designed to afford COFs with square-shaped pores and ultrahigh chemical stability (e.g., strong acid or alkali environments for >1 month). Functionalizing Fluorine significantly boosts the hydrophobicity of fluoro-functionalized COFs, which can inhibit the competing hydrogen evolution reaction (HER) and enhance ENRR performances. The COFs loading Pd nanoparticles show high NH3 production yields up to 90.0±2.6 μg ⋅ h-1 ⋅ mgcat. -1 and the faradaic efficiency of 44 % at -0.2 V versus reversible hydrogen electrode, the best comprehensive performance among all reported COFs. Meanwhile, the catalysts are easy to recover and recycle, as demonstrated by their use for 15 cycles and 17 hours, with good performance retention. This work not only provides a new synthesis strategy for olefin-linked COFs, but also paves a new avenue for the design of highly efficient ENRR catalysts.

Overcoming Gas Mass Transfer Limitations Using Gas-Conducting Electrodes for Efficient Nitrogen Reduction

Electrocatalytic nitrogen reduction reaction (NRR) is a very attractive strategy for ammonia synthesis due to its energy savings and sustainability. However, the ammonia yield and Faraday efficiency of electrocatalytic nitrogen reduction have been challenges due to low nitrogen solubility and competitive hydrogen evolution reaction (HER) in electrolyte solution. Herein, inspired by the asymmetric wetting behavior, i.e., superhydrophobicity/hydrophilicity, of floating lotus leaves, we demonstrated a gas-conduction electrode with asymmetric gas wetting behavior on the opposite surface, i.e., Janus-Ni/MoO2@NF, for efficient nitrogen reduction. It can provide an abundant three-phase interface (TPI) at interfaces of Janus-Ni/MoO2@NF in electrolyte solution to enhance the contact among N2, electrolyte, and electrode. Ascribed to this advantage, the hydrophobic side of the Janus electrode not only can repel water molecules to suppress the HER process but also can increase the concentration of N2 on the interface microenvironment. Consequently, the well-designed gas-conducting electrode breaks gas mass transfer limitation. Furthermore, Janus-Ni/MoO2@NF delivers a record-high NH3 yield rate of 5.865 μg·h-1·cm-2 and a Faradaic efficiency of 36.14% at an extremely low potential of 0 V vs RHE in 0.1 M Na2SO4 under ambient conditions, which are 22 and 18 times higher than those of the conventional electrode, respectively. Therefore, the gas-conducting electrodes can dramatically improve the activity and selectivity in electrocatalytic NRR. Additionally, the unique interface design provides inspiration for other sustainable electrochemical reactions involving gas electrocatalytic correlation.

Mesostructure-Specific Configuration of *CO Adsorption for Selective CO2 Electroreduction to C2+ Products

The multi-carbon (C2+) alcohols produced by electrochemical CO2 reduction, such as ethanol and n-propanol, are considered as indispensable liquid energy carriers. In most C-C coupling cases, however, the concomitant gaseous C2H4 product results in the low selectivity of C2+ alcohols. Here, we report rational construction of mesostructured CuO electrocatalysts, specifically mesoporous CuO (m-CuO) and cylindrical CuO (c-CuO), enables selective distribution of C2+ products. The m-CuO and c-CuO show similar selectivity towards total C2+ products (≥76 %), but the corresponding predominant products are C2+ alcohols (55 %) and C2H4 (52 %), respectively. The ordered mesostructure not only induces the surface hydrophobicity, but selectively tailors the adsorption configuration of *CO intermediate: m-CuO prefers bridged adsorption, whereas c-CuO favors top adsorption as revealed by in situ spectroscopies. Computational calculations unravel that bridged *CO adsorbate is prone to deep protonation into *OCH3 intermediate, thus accelerating the coupling of *CO and *OCH3 intermediates to generate C2+ alcohols; by contrast, top *CO adsorbate is apt to undergo conventional C-C coupling process to produce C2H4. This work illustrates selective C2+ products distribution via mesostructure manipulation, and paves a new path into the design of efficient electrocatalysts with tunable adsorption configuration of key intermediates for targeted products.

Modulating the Leverage Relationship in Nitrogen Fixation Through Hydrogen-Bond-Regulated Proton Transfer

In the electrochemical nitrogen reduction reaction (NRR), a leverage relationship exists between NH3-producing activity and selectivity because of the competing hydrogen evolution reaction (HER), which means that high activity with strong protons adsorption causes low product selectivity. Herein, we design a novel metal-organic hydrogen bonding framework (MOHBF) material to modulate this leverage relationship by a hydrogen-bond-regulated proton transfer pathway. The MOHBF material was composited with reduced graphene oxide (rGO) to form a Ni-N2O2 molecular catalyst (Ni-N2O2/rGO). The unique structure of O atoms in Ni-O-C and N-O-H could form hydrogen bonds with H2O molecules to interfere with protons being directly adsorbed onto Ni active sites, thus regulating the proton transfer mechanism and slowing the HER kinetics, thereby modulating the leverage relationship. Moreover, this catalyst has abundant Ni-single-atom sites enriched with Ni-N/O coordination, conducive to the adsorption and activation of N2. The Ni-N2O2/rGO exhibits simultaneously enhanced activity and selectivity of NH3 production with a maximum NH3 yield rate of 209.7 μg h-1 mgcat. -1 and a Faradaic efficiency of 45.7 %, outperforming other reported single-atom NRR catalysts.

Aldehyde Directed In Situ Loading of Ag Nanodots Around the Open Metal Sites of MOFs for the Tandem Catalysis of Nitrate to Ammonia

Both spatial arrangement and intrinsic activity of electrocatalysts with dual-active sites are widely designed to match the coupling reaction between nitrate and water, in which most of the reactive intermediates can be optimized to achieve a high yield rate of ammonia. Herein, by introducing the aldehyde group inside metal-organic frameworks (MOFs) in advance, an aldehyde-induced method is achieved to direct the in situ nucleation of Ag nanodots depending on the mesopores of MOFs via a simple silver mirror reaction. The key point here is that the spatial arrangement between the aldehyde group and open metal sites is fixed end to end, which makes the aldehyde group a built-in redox-active site to drive the in situ nucleation of Ag nanodots next to the open metal sites of MOFs. Accordingly, by varying the metal sites of MOFs, a group of M-MOFs@Ag (M = Fe, Co, Ni, Cu, etc.) hybrids with dual active sites are acquired. Taking Ni-MOFs@Ag as an example, the interaction between Ni2+ and Ag sites makes it available for the tandem catalysis of nitrate-to-ammonia, in which the H· and NO2 - generated on the open Ni2+ sites and Ag nanodots, respectively, can migrate to each other to evolve into ammonia.

Tailoring the d-Band Center of WS2 by Metal and Nonmetal Dual-Doping for Enhanced Electrocatalytic Nitrogen Reduction

Tuning the adsorption energy of nitrogen intermediates and lowering the reaction energy barrier is essential to accelerate the kinetics of nitrogen reduction reaction (NRR), yet remains a great challenge. Herein, the electronic structure of WS2 is tailored based on a metal and nonmetal dual-doping strategy (denoted Fe, F-WS2) to lower the d-band center of W in order to optimize the adsorption of nitrogen intermediates. The obtained Fe, F-WS2 nanosheet catalyst presents a high Faradic efficiency (FE) of 22.42% with a NH3 yield rate of 91.46 µg h-1 mgcat. -1. The in situ characterizations and DFT simulations consistently show the enhanced activity is attributed to the downshift of the d-band center, which contributes to the rate-determining step of the second protonation to form N2H2 * key intermediates, thereby boosting the overall nitrogen electrocatalysis reaction kinetics. This work opens a new avenue to enhanced electrocatalysis by modulating the electronic structure and surrounding microenvironment of the catalytic metal centers.

Fe─S Bond-Mediated Efficient Electron Transfer in Quantum Dots/Metal-Organic Frameworks for Boosting Photoelectrocatalytic Nitrogen Fixation

Effective electron supply to produce ammonia in photoelectrochemical nitrogen reduction reaction (PEC NRR) remains challenging due to the sluggish multiple proton-coupled electron transfer and unfavorable carrier recombination. Herein, InP quantum dots decorated with sulfur ligands (InP QDs-S2-) bound to MIL-100(Fe) as a benchmark catalyst for PEC NRR is reported. It is found that MIL-100(Fe) can combined with InP QDs-S2- via Fe─S bonds as bridge to facilitate the electron transfer by experimental results. The formation of Fe─S bonds can facilitate electron transfer from inorganic S2- ligands of InP QDs to the Fe metal sites of MIL-100(Fe) within 52 ps, ensuring a more efficient electron transfer and electron-hole separation confirmed by the time-resolved spectroscopy. More importantly, the process of photo-induced carrier transfer can be traced by in situ attenuated total reflection surface-enhanced infrared tests, certifying that the effective electron transfer can promote N≡N dissociation and N2 hydrogenation. As a result, InP QDs-S2-/MIL-100(Fe) exhibits prominent performance with an outstanding NH3 yield of 0.58 µmol cm-2 h-1 (3.09 times higher than that of MIL-100(Fe)). This work reveals an important ultrafast dynamic mechanism for PEC NRR in QDs modified metal-organic frameworks, providing a new guideline for the rational design of efficient MOFs photocathodes.

Microenvironment Engineering of Heterogeneous Catalysts for Liquid-Phase Environmental Catalysis

Environmental catalysis has emerged as a scientific frontier in mitigating water pollution and advancing circular chemistry and reaction microenvironment significantly influences the catalytic performance and efficiency. This review delves into microenvironment engineering within liquid-phase environmental catalysis, categorizing microenvironments into four scales: atom/molecule-level modulation, nano/microscale-confined structures, interface and surface regulation, and external field effects. Each category is analyzed for its unique characteristics and merits, emphasizing its potential to significantly enhance catalytic efficiency and selectivity. Following this overview, we introduced recent advancements in advanced material and system design to promote liquid-phase environmental catalysis (e.g., water purification, transformation to value-added products, and green synthesis), leveraging state-of-the-art microenvironment engineering technologies. These discussions showcase microenvironment engineering was applied in different reactions to fine-tune catalytic regimes and improve the efficiency from both thermodynamics and kinetics perspectives. Lastly, we discussed the challenges and future directions in microenvironment engineering. This review underscores the potential of microenvironment engineering in intelligent materials and system design to drive the development of more effective and sustainable catalytic solutions to environmental decontamination.

Defect Engineering in a Nanoporous Thulium-Organic Framework in Catalyzing Knoevenagel Condensation and Chemical CO2 Fixation

Defect engineering is an extremely effective strategy for modifying metal-organic frameworks (MOFs), which can break through the application limitations of traditional MOFs and enhance their functionality. Herein, we report a highly robust nanoporous thulium(III)-organic framework, {[Tm2(BDCP)(H2O)5](NO3)·3DMF·2H2O}n (NUC-105), with [Tm(COO)2(H2O)]n chains and [Tm2(COO)4(H2O)8] dinuclears as metal nodes and 2,6-bis(2,4-dicarboxylphenyl)-4-(4-carboxylphenyl)pyridine (BDCP) linkers. In NUC-105, each of the four chains of [Tm(COO)2]n and the two rows of [Tm2(COO)4(H2O)8] units is unified by the organic skeleton, resulting in a rectangular nanochannel with dimensions of 15.35 Å × 11.29 Å, which leads to a void volume of 50%. It is worth mentioning that the [Tm2(COO)4(H2O)8] cluster is very rare in terms of its higher level of associated water molecules, implying that the activated host framework can serve as a strong Lewis acid. NUC-105a exhibited great heterogeneous catalytic performance for CO2 cycloaddition with epoxides under the reaction conditions (0.60 mol % NUC-105a, 5.0 mol % n-Bu4NBr, 65 °C, 5 h), ensuring exclusive selectivity and high conversion rates. In addition, NUC-105a's strong catalytic impact on the Knoevenagel condensation of aldehydes and malononitrile can be attributed to the collaboration between the drastically unsaturated Lewis acidic Tm3+ centers and Lewis basic pyridine groups.

Highly Efficient Continuous Flow Nanocatalyst Platform Constructed with Regenerable Bacterial Cellulose Loaded with Gold Nanoparticles and a Nanoporous Membrane

With the development of society and the growing concern about environmental issues, continuous flow catalytic reactors have gained significant interest due to their resource-efficient advantages over traditional batch devices. In this study, we employed a facile one-step in situ reduction approach to construct highly dispersed gold nanoparticles loaded on regenerable bacterial cellulose nanofiber (BCN) heterogeneous catalysts. These catalysts, in combination with a nanoceramic membrane with a pore size of 1 nm, formed a fully mixed system that was favorable for the efficient continuous flow catalysis of selective reduction reactions of nitrophenol. The reaction system demonstrated remarkable catalytic activity toward nitrophenol reduction reactions at low reductant dosages (<5 equiv), achieving over 95% conversion and 99% selectivity for the aniline product in 10 min under room temperature conditions. Furthermore, continuous flow operations maintained stable catalytic activity with minimal catalyst loss after a 120-h test and were 3 times more time-efficient than batch operations. Additionally, continuous monitoring could be conducted through ultraviolet (UV) spectroscopy. A highly efficient and environmentally friendly strategy was present for designing continuous flow reactions in future applications.

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.

Defect-engineered indium-organic framework displays the higher CO2 adsorption and more excellent catalytic performance on the cycloaddition of CO2 with epoxides under mild conditions

In order to achieve the high adsorption and catalytic performance of CO2, the direct self-assembly of robust defect-engineered MOFs is a scarcely reported and challenging proposition. Herein, a highly robust nanoporous indium(III)-organic framework of {[In2(CPPDA)(H2O)3](NO3)·2DMF·3H2O}n (NUC-107) consisting of two kinds of inorganic units of chain-shaped [In(COO)2(H2O)]n and watery binuclear [In2(COO)4(H2O)8] was generated by regulating the growth environment. It is worth mentioning that [In2(COO)4(H2O)8] is very rare in terms of its richer associated water molecules, implying that defect-enriched metal ions in the activated host framework can serve as strong Lewis acid. Compared to reported skeleton of [In4(CPPDA)2(μ3-OH)2(DMF)(H2O)2]n (NUC-66) with tetranuclear clusters of [In4(μ3-OH)2(COO)10(DMF)(H2O)2] as nodes, the void volume of NUC-107 (50.7%) is slightly lower than the one of NUC-66 (52.8%). However, each In3+ ion in NUC-107 has an average of 1.5 coordinated small molecules (H2O), which far exceeds the average of 0.75 in NUC-66 (H2O and DMF). After thermal activation, NUC-107a characterizes the merits of unsaturated In3+ sites, free pyridine moieties, solvent-free nanochannels (10.2 × 15.7 Å2). Adsorption tests prove that the host framework of NUC-107a has a higher CO2 adsorption (113.2 cm3/g at 273 K and 64.8 cm3/g at 298 K) than NUC-66 (91.2 cm3/g at 273 K and 53.0 cm3/g at 298 K). Catalytic experiments confirmed that activated NUC-107a with the aid of n-Bu4NBr was capable of efficiently catalyzing the cycloaddition of CO2 with epoxides into corresponding cyclic carbonates under the mild conditions. Under the similar conditions of 0.10 mol% MOFs, 0.5 mol% n-Bu4NBr, 0.5 MP CO2, 60 °C and 3 h, compared with NUC-66a, the conversion of SO to SC catalyzed by NUC-107a increased by 21%. Hence, this work offers a valuable perspective that the in situ creation of robust defect-engineered MOFs can be realized by regulating the growth environment.

Zirconium-based metal-organic frameworks and their roles in electrocatalysis

Due to their exceptional chemical stability in water and high structural tunability, zirconium(IV)-based MOFs (Zr-MOFs) have been considered attractive materials in the broad fields of electrocatalysis. Numerous studies published since 2015 have attempted to utilise Zr-MOFs in electrocatalysis, with the porous framework serving as either the active electrocatalyst or the scaffold or surface coating to further enhance the performance of the actual electrocatalyst. Herein, the roles of Zr-MOFs in electrocatalytic processes are discussed, and some selected examples reporting the applications of Zr-MOFs in various electrocatalytic reactions, including several studies from our group, are overviewed. Challenges, limitations and opportunities in using Zr-MOFs in electrocatalysis in future studies are discussed.

A Review of Anode Materials for Dual-Ion Batteries

Distinct from "rocking-chair" lithium-ion batteries (LIBs), the unique anionic intercalation chemistry on the cathode side of dual-ion batteries (DIBs) endows them with intrinsic advantages of low cost, high voltage, and eco-friendly, which is attracting widespread attention, and is expected to achieve the next generation of large-scale energy storage applications. Although the electrochemical reactions on the anode side of DIBs are similar to that of LIBs, in fact, to match the rapid insertion kinetics of anions on the cathode side and consider the compatibility with electrolyte system which also serves as an active material, the anode materials play a very important role, and there is an urgent demand for rational structural design and performance optimization. A review and summarization of previous studies will facilitate the exploration and optimization of DIBs in the future. Here, we summarize the development process and working mechanism of DIBs and exhaustively categorize the latest research of DIBs anode materials and their applications in different battery systems. Moreover, the structural design, reaction mechanism and electrochemical performance of anode materials are briefly discussed. Finally, the fundamental challenges, potential strategies and perspectives are also put forward. It is hoped that this review could shed some light for researchers to explore more superior anode materials and advanced systems to further promote the development of DIBs.

Pre-Adsorbed H-Mediated Electrochemiluminescence

In conventional electrochemiluminescence (ECL) systems, the presence of the competitive cathodic hydrogen evolution reaction (HER) in aqueous electrolytes is typically considered to be a side reaction, leading to a reduced ECL efficiency and stability due to H2 generation and aggregation at the electrode surface. However, the significant role of adsorbed hydrogen (H*) as a key intermediate, formed during the Volmer reaction in the HER process, has been largely overlooked. In this study, employing the luminol-H2O2 system as a model, we for the first time demonstrate a novel H*-mediated coreactant activation mechanism, which remarkably enhances the ECL intensity. H* facilitates cleavage of the O-O bond in H2O2, selectively generating highly reactive hydroxyl radicals for efficient ECL reactions. Experimental investigations and theoretical calculations demonstrate that this H*-mediated mechanism achieves superior coreactant activation compared to the conventional direct electron transfer pathway, which unveils a new pathway for coreactant activation in the ECL systems.

Hierarchical MOFs with Good Catalytic Properties and Structural Stability in Oxygen-Rich and High-Temperature Environments

Metal-organic framework materials are ideal materials characterized by open frameworks, adjustable components, and high catalytic activity. They are extensively utilized for catalysis. Due to decomposition and structural collapse under high temperatures and an oxygen-rich environment, the potential of thermal catalysis is greatly limited. In this research, Co-rich hollow spheres (Co-HSs) with a gradient composition are designed and synthesized to investigate their thermal catalytic properties in the ammonium perchlorate（AP）system. The results demonstrate that Co-HSs@AP exhibits good thermal catalytic activity and a high-temperature decomposition of 292.5 °C, which is 121.6 °C lower than pure AP. The hierarchical structure confers structural stability during the thermal decomposition process. Thermogravimetry-infrared indicates that the inclusion of Co-HSs successfully boosts the level of reactive oxygen species and achieves thorough oxidation of NH3. Based on the above phenomenon, macro dynamics calculations are carried out. The results show that Co-HSs can promote the circulation of lattice oxygen and reactive oxygen species and the multidimensional diffusion of NH3 in an oxygen-rich environment. This material has significant potential for application in the fields of thermal catalysis and ammonia oxidation.

Enhanced Molecular Interaction of 3D Plasmonic Nanoporous Gold Alloys by Electronic Modulation for Sensitive Molecular Detection

Three-dimensional gold and its alloyed nanoporous structures possess high surface areas and strong local electric fields, rendering them ideal substrates for plasmonic molecular detection. Despite enhancing plasmonic properties and altering molecular interactions, the effect of alloy composition on molecular detection capability has not yet been explored. Here, we report molecular interactions between nanoporous gold alloys and charged molecules by controlling the alloy composition. We demonstrate enhanced adsorption of negatively charged molecules onto the alloy surface due to positively charged gold atoms and a shifted d-band center through charge transfer between gold and other metals. Despite similar EM field intensities, nanoporous gold with silver (Au/Ag) achieves SERS enhancement factors (EF) up to 6 orders of magnitude higher than those of other alloys for negatively charged molecules. Finally, nanoporous Au/Ag detects amyloid-beta at concentrations as low as approximately 1 fM, with SERS EF up to 10 orders of magnitude higher than that of a monolayer of Au nanoparticles.

Metalation of metal-organic frameworks: fundamentals and applications

Metalation of metal-organic frameworks (MOFs) has been developed as a prominent strategy for materials functionalization for pore chemistry modulation and property optimization. By introducing exotic metal ions/complexes/nanoparticles onto/into the parent framework, many metallized MOFs have exhibited significantly improved performance in a wide range of applications. In this review, we focus on the research progress in the metalation of metal-organic frameworks during the last five years, spanning the design principles, synthetic strategies, and potential applications. Based on the crystal engineering principles, a minor change in the MOF composition through metalation would lead to leveraged variation of properties. This review starts from the general strategies established for the incorporation of metal species within MOFs, followed by the design principles to graft the desired functionality while maintaining the porosity of frameworks. Facile metalation has contributed a great number of bespoke materials with excellent performance, and we summarize their applications in gas adsorption and separation, heterogeneous catalysis, detection and sensing, and energy storage and conversion. The underlying mechanisms are also investigated by state-of-the-art techniques and analyzed for gaining insight into the structure-property relationships, which would in turn facilitate the further development of design principles. Finally, the current challenges and opportunities in MOF metalation have been discussed, and the promising future directions for customizing the next-generation advanced materials have been outlined as well.

Boosting Electrocatalytic N2 Reduction to NH3 by Enhancing N2 Activation via Interaction between Au Nanoparticles and MIL-101(Fe) in Neutral Electrolytes

Electrocatalytic nitrogen reduction reaction (NRR) has attracted much attention as a sustainable ammonia production technology, but it needs further exploration due to its slow kinetics and the existence of competitive side reactions. In this research, xAu/MIL-101(Fe) catalysts were obtained by loading gold nanoparticles (Au NPs) onto MIL-101(Fe) using a one-step reduction strategy. Herein, MIL-101(Fe), with high specific surface area and strong N2 adsorption capacity, is used as a support to disperse Au NPs to increase the electrochemical active surface area. Au NPs, with a high NRR activity, is introduced as the active site to promote charge transfer and intermediate formation rates. More importantly, the strong interaction between Au NPs and MIL-101(Fe) enhances the electron transfer between Au NPs and MIL-101(Fe), thereby enhancing the activation of N2 and achieving efficient NRR. Among the prepared catalysts, 15 %Au/MIL-101(Fe) has the highest NH3 yield of 46.37 μg h-1 mg-1 cat and a Faraday efficiency of 39.38 % at -0.4 V (vs. RHE). In-situ FTIR reveals that the NRR mechanism of 15 %Au/MIL-101(Fe) follows the binding alternating pathway and also indicates that the interaction between Au NPs and MIL-101(Fe) strengthens the activation of the N≡N bond in the rate-limiting process, thereby accelerating the NRR process.

Tailoring the efficiency of porphyrin molecular frameworks for the electroactivation of molecular N2

The combination of compositional versatility and topological diversity for the integration of electroactive species into high-porosity molecular architectures is perhaps one of the main appeals of metal-organic frameworks (MOFs) in the field of electrocatalysis. This premise has attracted much interest in recent years, and the results generated have also revealed one of the main limitations of molecular materials in this context: low stability under electrocatalytic conditions. Using zirconium MOFs as a starting point, in this work, we use this stability as a variable to discriminate between the most suitable electrocatalytic reaction and specific topologies within this family. Our results revealed that the PCN-224 family is particularly suitable for the electroreduction of molecular nitrogen for the formation of ammonia with faradaic efficiencies above 30% in the presence of Ni2+ sites, an activity that improves most of the catalysts described. We also introduce the fluorination of porphyrin at the meso position as a good alternative to improve both the activity and stability of this material under electrocatalytic conditions.

Interface Engineering-Modulated Nanoscale Bimetallic CoFe-MIL-88A In-Situ-Grown on 2D V2CTx MXene for Electrocatalytic Nitrogen Reduction

The electrochemical nitrogen reduction reaction (eNRR) provides a sustainable green development route for the nitrogen-neutral cycle. In this work, bimetallic CoFe-MIL-88A with two active sites (Fe, Co) were immobilized on a 2D V2CTx MXene surface by in situ growth method to achieve the purpose of the control interface. A large number of heterostructures are formed between small CoFe-MIL-88A and V2CTx, which regulate the electron transfer between the catalyst interfaces. The adsorption and activation of nitrogen on the active sites were enhanced, and the NRR reaction kinetics was accelerated. CoFe-MIL-88A is tightly arranged on V2CTx, which makes CoFe-MIL-88A/V2CTx have better hydrophobicity and can significantly inhibit the hydrogen evolution reaction. The synergistic effect of multicatalytic active sites and multi-interface structure of CoFe-MIL-88A/V2CTx MXene is propitious to nitrogen efficiently and stably to convert into ammonia under environmental conditions with superior selectivity and good catalytic activity. The NH3 yield rate is 29.47 μg h-1 mgcat-1 at -0.3 V vs RHE, and the Faradaic efficiency (FE) is 28.86% at -0.1 V vs RHE. The catalytic mechanism was verified to conform to the distal pathway. This work will provide a new way to develop an MXene-based electrocatalyst for eNRR.

Metal-Organic Framework (MOF)-Based Clean Energy Conversion: Recent Advances in Unlocking its Underlying Mechanisms

Carbon neutrality is an important goal for humanity . As an eco-friendly technology, electrocatalytic clean energy conversion technology has emerged in the 21st century. Currently, metal-organic framework (MOF)-based electrocatalysis, including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), carbon dioxide reduction reaction (CO2RR), nitrogen reduction reaction (NRR), are the mainstream energy catalytic reactions, which are driven by electrocatalysis. In this paper, the current advanced characterizations for the analyses of MOF-based electrocatalytic energy reactions have been described in details, such as density function theory (DFT), machine learning, operando/in situ characterization, which provide in-depth analyses of the reaction mechanisms related to the above reactions reported in the past years. The practical applications that have been developed for some of the responses that are of application values, such as fuel cells, metal-air batteries, and water splitting have also been demonstrated. This paper aims to maximize the potential of MOF-based electrocatalysts in the field of energy catalysis, and to shed light on the development of current intense energy situations.

Electron-Rich Ru Supported on N-Doped Coffee Biochar for Selective Reductive Amination of Furfural to Furfurylamine

Highly selective synthesis of primary amines from renewable biomass has attracted increasing attention, but it still faces great challenges in chemical industry applications. In this study, an electron-rich Ru catalyst was constructed by doping N into coffee biochar using a one-pot carbonization method (Ru/NCB-600). Ru/NCB-600 showed high catalytic activity and yield for the reductive amination of furfural with green and cheap NH3 and H2. The excellent catalytic performance of Ru/NCB-600 was closely correlated to the formation of electron-rich Ruδ- species (Ruδ--Nxδ+), which endowed Ru/NCB-600 with an enhanced H2 adsorption and activation ability. Ru/NCB-600 showed a high formation rate of 95.6 gfurfurylamine·gRu-1·h-1 and a high yield of furfurylamine (98.6%) at 50 °C. Ru/NCB-600 can also be used for the reductive amination of various carbonyl compounds in good to excellent yield (95.4-99%). This study thus provides a potential pathway for the highly selective reductive amination of carbonyl compounds by regulating the electron density of Ru.

Highly Stable 72-Nuclearity Nanocages for Efficient Synthesis of Aryl Nitriles via Ni/Cu Synergistic Catalysis

Seeking noble-metal-free catalysts for efficient synthesis of aryl nitriles under mild conditions poses a significant challenge due to the use of hypertoxic cyanides or high-pressure/temperature NH3/O2 in conventional synthesis processes. Herein, we developed a novel framework 1 assembled by [Ni72] nanocages with excellent solvents/pH stability. To investigate the structure-activity relationship of catalytic performance, several isostructural MOFs with different molar ratios of Ni/Cu by doping Cu2+ into framework 1 (Ni0.59Cu0.41 (2), Ni0.81Cu0.19 (3), Ni0.88Cu0.12 (4), and Ni0.92Cu0.08 (5)) were prepared. Catalytic studies revealed that catalyst 3 exhibited remarkable performance in the synthesis of aryl nitriles, utilizing a formamide alternative to hypertoxic NaCN/KCN. Notably, catalyst 3 achieved an excellent TOF value of 9.8 h-1. Furthermore, catalyst 3 demonstrated its applicability in a gram-scale experiment and maintained its catalytic performance even after six recycling cycles, owing to its high stability resulting from significant electrostatic and orbital interactions between the Ni center and ligands as well as a large SOMO-LUMO energy gap supported by DFT calculations. Control experiments and DFT calculations further revealed that the excellent catalytic performance of catalyst 3 originated from the synergistic effect of Ni/Cu. Importantly, this work not only provides a highly feasible method to construct highly stable MOFs containing multinuclear nanocages with exceptional catalytic performance but also represents the first example of a heterogeneous catalyst for the synthesis of aryl nitriles using formamide as the cyanide source.

Recent Advances in Electrocatalytic Hydrogenation Reactions on Copper-Based Catalysts

Hydrogenation reactions play a critical role in the synthesis of value-added products within the chemical industry. Electrocatalytic hydrogenation (ECH) using water as the hydrogen source has emerged as an alternative to conventional thermocatalytic processes for sustainable and decentralized chemical synthesis under mild conditions. Among the various ECH catalysts, copper-based (Cu-based) nanomaterials are promising candidates due to their earth-abundance, unique electronic structure, versatility, and high activity/selectivity. Herein, recent advances in the application of Cu-based catalysts in ECH reactions for the upgrading of valuable chemicals are systematically analyzed. The unique properties of Cu-based catalysts in ECH are initially introduced, followed by design strategies to enhance their activity and selectivity. Then, typical ECH reactions on Cu-based catalysts are presented in detail, including carbon dioxide reduction for multicarbon generation, alkyne-to-alkene conversion, selective aldehyde conversion, ammonia production from nitrogen-containing substances, and amine production from organic nitrogen compounds. In these catalysts, the role of catalyst composition and nanostructures toward different products is focused. The co-hydrogenation of two substrates (e.g., CO2 and NOx n, SO3 2-, etc.) via C─N, C─S, and C─C cross-coupling reactions are also highlighted. Finally, the critical issues and future perspectives of Cu-catalyzed ECH are proposed to accelerate the rational development of next-generation catalysts.

Biomimetic Design of a Dynamic M-O-V Pyramid Electron Bridge for Enhanced Nitrogen Electroreduction

Electrochemical nitrogen reduction reaction (eNRR) offers a sustainable route for ammonia synthesis; however, current electrocatalysts are limited in achieving optimal performance within narrow potential windows. Herein, inspired by the heliotropism of sunflowers, we present a biomimetic design of Ru-VOH electrocatalyst, featuring a dynamic Ru-O-V pyramid electron bridge for eNRR within a wide potential range. In situ spectroscopy and theoretical investigations unravel the fact that the electrons are donated from Ru to V at lower overpotentials and retrieved at higher overpotentials, maintaining a delicate balance between N2 activation and proton hydrogenation. Moreover, N2 adsorption and activation were found to be enhanced by the Ru-O-V moiety. The catalyst showcases an outstanding Faradaic efficiency of 51.48% at -0.2 V (vs RHE) with an NH3 yield rate exceeding 115 μg h-1 mg-1 across the range of -0.2 to -0.4 V (vs RHE), along with impressive durability of over 100 cycles. This dynamic M-O-V pyramid electron bridge is also applicable to other metals (M = Pt, Rh, and Pd).

Recent advances in ambient-stable black phosphorus materials for artificial catalytic nitrogen cycle in environment and energy

Nitrogen cycle is crucial for the Earth's ecosystem and human-nature coexistence. However, excessive fertilizer use and industrial contamination disrupt this balance. Semiconductor-based artificial nitrogen cycle strategies are being actively researched to address this issue. Black phosphorus (BP) exhibits remarkable performance and significant potential in this area due to its unique physical and chemical properties. Nevertheless, its practical application is hindered by ambient instability. This review covers the synthesis methods of BP materials, analyzes their instability factors under environmental conditions, discusses stability improvement strategies, and provides an overview of the applications of ambient-stable BP materials in nitrogen cycle, including N2 fixation, NO3- reduction, NOx removal and nitrides sensing. The review concludes by summarizing the challenges and prospects of BP materials in the nitrogen cycle, offering valuable guidance to researchers.

Synergistic Effect of Oxygen Vacancy and High Porosity of Nano MIL-125(Ti) for Enhanced Photocatalytic Nitrogen Fixation

This work reports that a low-temperature thermal calcination strategy was adopted to modulate the electronic structure and attain an abundance of surface-active sites while maintaining the crystal morphology. All the experiments demonstrate that the new photocatalyst nano MIL-125(Ti)-250 obtained by thermal calcination strategy has abundant Ti3+ induced by oxygen vacancies and high specific surface area. This facilitates the adsorption and activation of N2 molecules on the active sites in the photocatalytic nitrogen fixation. The photocatalytic NH3 yield over MIL-125(Ti)-250 is enhanced to 156.9 μmol g-1  h-1 , over twice higher than that of the parent MIL-125(Ti) (76.2 μmol g-1  h-1 ). Combined with density function theory (DFT), it shows that the N2 adsorption pattern on the active sites tends to be from "end-on" to "side-on" mode, which is thermodynamically favourable. Moreover, the electrochemical tests demonstrate that the high atomic ratio of Ti3+ /Ti4+ can enhance carrier separation, which also promotes the efficiency of photocatalytic N2 fixation. This work may offer new insights into the design of innovative photocatalysts for various chemical reduction reactions.

Efficient Electroreduction of Nitrate to Ammonia with CuPd Nanoalloy Catalysts

The electroreduction of nitrate (NO3 - ) to valuable ammonia (NH3 ) is a green and appealing alternative to the Haber-Bosch process. Nevertheless, this process suffers from low performance for NH3 due to the sluggish multi-electron/proton-involved steps. In this work, a CuPd nanoalloy catalyst was developed toward NO3 - electroreduction at ambient conditions. By modulating the atomic ratio of Cu to Pd, the hydrogenation steps of NH3 synthesis during NO3 - electroreduction can be effectively controlled. At -0.7 V versus reversible hydrogen electrode (vs. RHE), the optimized CuPd electrocatalysts achieved a Faradaic efficiency for NH3 of 95.5 %, which was 1.3 and 1.8 times higher than that of Cu and Pd, respectively. Notably, at -0.9 V vs. RHE, the CuPd electrocatalysts showed a high yield rate of 36.2 mg h-1  cm-2 for NH3 with a corresponding partial current density of -430.6 mA cm-2 . Mechanism investigation revealed the enhanced performance originated from the synergistic catalytic cooperation between Cu and Pd sites. The H-atoms adsorbed on the Pd sites prefer to transfer to adjacent nitrogen intermediates adsorbed on the Cu sites, thereby promoting the hydrogenation of intermediates and the formation of NH3 .

A simple hydrothermal synthesis of an oxygen vacancy-rich MnMoO4 rod-like material and its highly efficient electrocatalytic nitrogen reduction

Electrocatalytic nitrogen reduction (NRR) for artificial ammonia synthesis under ambient conditions is considered a promising alternative to the traditional Haber-Bosch process. However, it still faces multiple challenges such as the difficulty of N2 adsorption and activation and limited Faraday efficiency. In this work, a bimetallic oxide MnMoO4 was prepared by a hydrothermal method and low temperature calcination. The influence of the sintering temperature on the microstructure (crystallinity and oxygen vacancies) of the oxide and its NRR properties were systematically explored. The results showed that MnMoO4 sintered at 500 °C had the highest concentration of OVs and showed excellent NRR performance, with the highest NH3 yield (up to 12.28 μg h-1 mgcat-1), high Faraday efficiency (23.04% at -0.30 V vs. RHE), and good stability at -0.40 V vs. RHE, and the catalytic performance was about two times higher than that of Mn2O3 and MoO3. It is also superior to other bimetallic oxide NRR electrocatalysts reported in some cases. In addition, we also explored the ratio between Mn and Mo metals, and the catalytic effect was the best when Mn : Mo = 1 : 1. Due to the synergistic effect between Mn and Mo metals and the large number of OVs present internally, the catalytic activity for the NRR was largely improved. This study suggests that the bimetallic oxide MnMoO4 may be a promising NRR electrocatalyst.

Double-single-atom MoCu-embedded porous carbons boost the electrocatalytic N2 reduction reaction

NH3 is an essential ingredient of chemical, fertilizer, and energy storage products. Industrial nitrogen fixation consumes an enormous amount of energy, which is counter to the concept of carbon neutrality, hence eNRR ought to be implemented as a clean alternative. Herein, we propose a double-single-atom MoCu-embedded porous carbon material derived from uio-66 (MoCu@C) by plasma-enhanced chemical vapor deposition (PECVD) to boost eNRR capabilities, with an NH3 yield rate of 52.4 μg h-1 gcat.-1 and a faradaic efficiency (FE) of 27.4%. Advanced XANES shows that the Mo active site receives electrons from Cu, modifies the electronic structure of the Mo active site and enhances N2 adsorption activation. The invention of rational MoCu double-single-atom materials and the utilization of effective eNRR approaches furnish the necessary building blocks for the fundamental study and practical application of Mo-based materials.

Regulating Intramolecular Electron Transfer of Nickel-Based Coordinations through Ligand Engineering for Aqueous Batteries

The integration of electronic effects into complexes for the construction of novel materials has not yet attracted significant attention in the field of energy storage. In the current study, eight one-dimensional (1D) nickel-based salicylic acid  complexes (Ni-XSAs, X = pH, pMe, pMeO, mMe, pBr, pCl, pF, and pCF3 ), are prepared by ligand engineering. The coordination environments in the Ni-XSAs are explored using X-ray absorption fine structure spectroscopy. The charge transfer of the complexes is modulated according to the difference in the electron-donating ability of the substituents, in combination with frontier orbital theory. Furthermore, density functional theory is used to investigate the effect of the substituent position on the electronic properties of the complexes. Ni-mMeSA exhibits better electrical conductivity than Ni-pMeSA. The electrochemical performance of Ni-mMeSA as an aqueous battery cathode is remarkably improved with a maximum energy density of 0.30 mWh cm-2 (125 Wh kg-1 ) and a peak power density of 33.72 mW cm-2 (14.03 kW kg-1 ). This study provides ideas for the application of new coordination chemistry in the field of energy materials science.

Recent Advances in Metal-Organic Framework-Based Nanomaterials for Electrocatalytic Nitrogen Reduction

The production of ammonia under moderate conditions is of environmental and sustainable importance. The electrochemical nitrogen reduction reaction (E-NRR) method has been intensively investigated in the recent decades. Nowadays, the further development of E-NRR is largely hindered by the lack of competent electrocatalysts. Metal-organic frameworks (MOFs) are considered as the next-generation catalysts for E-NRR, featuring their tailorable structures, abundant active sites and favorable porosity. To present a comprehensive review on both the fundamental and advanced development in MOFs catalyst-based E-NRR field, this paper first introduces the basic principles of E-NRR, including the reaction mechanism, major apparatus components, performance criteria, and ammonia detection protocols. Next, the synthesis and characterization methods for MOFs and their derivatives are discussed. In addition, a reaction mechanism study via density functional theory calculations is also presented. After that, the recent advancement of MOF-based catalysts in the E-NRR field as well as the modification approaches on MOFs for E-NRR optimization is elaborated. Finally, the current challenges and outlook of MOF catalyst-based E-NRR field are emphasized.

Nanoengineering Metal-Organic Frameworks and Derivatives for Electrosynthesis of Ammonia

Electrocatalytic synthesis under mild conditions has become increasingly important as one of the practical alternatives for industrial applications, especially for the green ammonia (NH3) industry. A properly engineered electrocatalyst plays a vital role in the realization of superior catalytic performance. Among various types of promising nanomaterials, metal-organic frameworks (MOFs) are competitive candidates for developing efficient electrocatalytic NH3 synthesis from simple nitrogen-containing molecules or ions, such as N2 and NO3-. In this review, recent advances in the development of electrocatalysts derived from MOFs for the electrosynthesis of NH3 are collected, categorized, and discussed, including their application in the N2 reduction reaction (NRR) and the NO3- reduction reaction (NO3RR). Firstly, the fundamental principles are illustrated, such as plausible mechanisms of NH3 generation from N2 and NO3-, the apparatus of corresponding electrocatalysis, parameters for evaluation of reaction efficiency, and detection methods of yielding NH3. Then, the electrocatalysts for NRR processes are discussed in detail, including pristine MOFs, MOF-hybrids, MOF-derived N-doped porous carbons, single atomic catalysts from pyrolysis of MOFs, and other MOF-related materials. Subsequently, MOF-related NO3RR processes are also listed and discussed. Finally, the existing challenges and prospects for the rational design and fabrication of electrocatalysts from MOFs for electrochemical NH3 synthesis are presented, such as the evolution of investigation methods with artificial intelligence, innovation in synthetic methods of MOF-related catalysts, advancement of characterization techniques, and extended electrocatalytic reactions.

Dynamic behavior of metal nanoparticles in MOF materials: analysis with electron microscopy and deep learning

Electron microscopy is a key characterization technique for nanoscale systems, and electron microscopy images are typically recorded and analyzed in terms of the morphology of the objects under study in static mode. The emerging current trend is to analyze the dynamic behavior at the nanoscale observed during electron microscopy measurements. In this work, the study of the stability of MOF structures with different compositions and topologies under conditions of an electron microscope experiment revealed an unusual dynamic behavior of M NPs formed due to the electron-beam-induced transformation of specific frameworks. The transition to the liquid phase led to spatial movement, rapid sintering, and an increase in the M NPs size within seconds. In the case of copper nanoparticles, instantaneous sublimation was observed. The dynamic behavior of Co NPs was analyzed with a computational framework combining deep learning and classic computer vision techniques. The present study for the first time revealed unique information about the stability of a variety of MOFs under an electron beam and the dynamic behavior of the formed M NPs. The formation of Fe, Ni, Cu, and Co NPs was observed from a molecular framework with a specific subsequent behavior - a stable form for Fe, excessive dynamics for Co, and sublimation/condensation for Cu. Two important outcomes of the present study should be mentioned: (i) electron microscopy investigations of MOF samples should be made with care, as decomposition under an electron beam may lead to incorrect results and the appearance of "phantom" nanoparticles; and (ii) MOFs represent an excellent model for fundamental studies of molecular-to-nano transitions in situ in video mode, including a number of dynamic transformations.