Diverse Pore Research Articles

Porous Carbon‐Supported Catalysts for Proton Exchange Membrane Fuel Cells

AbstractProton exchange membrane fuel cells (PEMFCs) are crucial for the efficient utilization of hydrogen. Currently, their efficiency is mainly limited by the slow kinetics of the cathode oxygen reduction reaction (ORR) and the poisoning effect between ionomers and catalytic sites, particularly with Pt‐based catalysts. Recent works suggest that the emerging porous carbon‐supported catalysts hold promise in mitigating these challenges by ensuring fast kinetics while alleviating the poisoning. This review examines porous carbon‐supported catalysts for PEMFC cathodes, covering synthesis methods, structure and performance evaluation, and future prospects, with an emphasis on the influence of porous carbon support on PEMFC performance. On one hand, the rational design of pore structure in carbon support can help optimize the location of the active sites and enhance mass transfer. On the other hand, diverse pore structures provide a platform for gaining a deeper understanding of the mechanisms behind microscale mass transfer and reaction at the three‐phase boundaries. This review aims to inspire innovative strategies for the precise synthesis of porous carbon‐supported catalysts with various pore structures to further boost PEMFC performance.

3D Covalent Organic Framework Membranes for Molecular Separations.

Membrane separation has become an indispensable separation technology in social production, playing an important role in drug production, water purification, etc. The key core of membranes lies in achieving efficient and precise sieving between substances. As a result, a typical trade-off arises: highly permeable membranes usually sacrifice selectivity and vice versa. To address this dilemma, long-term research has focused on comprehensive understanding and modelling of synthetic membranes at various scales. A significant advancement in this arena is the advent of three-dimensional covalent organic framework (3D COF) membranes, a novel category of long-range ordered porous organic polymer materials. Characterized by an abundance of interconnected channels, diverse pore wall properties, tunable structures, and robust thermal and chemical resilience, 3D COF membranes offer a promising approach for efficient substance separation. This review undertakes a meticulous investigation of the synthesis and physicochemical properties of 3D COF membranes, accentuating the underlying design principles, fabrication methods, and application attempts. A comprehensive assessment of their research trajectory and current standing in the field of membrane processes is provided. The review culminates in a forward-looking outlook, summarizing future research directions and highlighting the substantial potential of this innovative work to shape the future of efficient membrane separation processes.

Regulating the Pore Structure of Biomass-Derived Hard Carbon for an Advanced Sodium-Ion Battery.

Biomass-derived hard carbon materials are attractive for sodium-ion batteries due to their abundance, sustainability, and cost-effectiveness. However, their widespread use is hindered by their limited specific capacity. Herein, a type of bamboo-derived hard carbon with adjustable pore structures is developed by employing a ball milling technique to modify the carbon chain length in the precursor. It is observed that the length of the carbon chain in the precursor can effectively control the rearrangement behavior of the carbon layers during the high-temperature carbonization process, resulting in diverse pore structures ranging from closed pores to open pores, which significantly impact the electrochemical properties. The optimized hard carbon with abundant closed pores exhibits a high specific capacity of 356 mAh g-1 at 20 mA g-1, surpassing that of bare hard carbon (243 mAh g-1) and hard carbon with abundant open pores (129 mAh g-1 at 20 mA g-1). However, the kinetic analysis reveals that hard carbon with open pores shows better sodium-ion diffusion kinetics, indicating that a balance between the closed and open pores should be considered. This research offers valuable insights into pore design and presents a promising approach for enhancing the performance of hard carbon anode materials derived from biomass precursors.

A Green Approach to Oil Spill Mitigation: New Hybrid Materials for Wastewater Treatment.

This study focuses on the development of adsorptive materials to retain degraded 5w40 motor oil. The materials were prepared using xanthan (XG) and XG esterified with acrylic acid (XGAC) as the polymeric matrix. LignoBoost lignin (LB), LB esterified with oleic (LBOL), stearic acid (LBST) and montmorillonite (CL) were added into XG and XGAC matrices to obtain the adsorbents. Adsorption experiments revealed that XG/CL/LBOL had the highest adsorption capacity at 46.80 g/g, followed by XGAC/CL at 45.73 g/g, and XG/CL at 37.58 g/g. The kinetic studies, employing the pseudo-second-order (PSO) model, indicated rapid sorption rates with a good correlation to experimental data. FTIR spectra analysis have evidenced the physical nature of adsorption process, involving interactions such as hydrogen bonding, van der Waals forces, and π-π interactions. Equilibrium data fitting to the Henry, Freundlich, and Temkin isotherm models showed that the adsorption occurs within materials diverse pore structures, enhancing oil retention. Structural parameters like density, porosity, and surface area were pivotal, with XG/CL/LBOL showing the most favorable properties for high oil adsorption. Additionally, it was found that the adsorption efficiency was influenced by the material's morphology and the presence of chemical modifications. This comprehensive evaluation highlights the potential of these novel adsorptive materials for environmental remediation applications, offering an efficient and sustainable approach to reducing degraded motor oil pollution.

Interconversion and functional composites of metal-organic frameworks and hydrogen-bonded organic frameworks.

Metal-organic frameworks (MOFs), an emerging class of highly ordered crystalline porous materials, possess structural tunability, high specific surface area, well-defined pores, and diverse pore environments and morphologies, making them suitable for various potential applications. Moreover, hydrogen-bonded organic frameworks (HOFs), constructed from organic molecules with complementary hydrogen-bonding patterns, are rapidly evolving into a novel category of porous materials due to their facile mild preparation conditions, solution processability, easy regeneration capability, and excellent biocompatibility. These distinctive advantages have garnered significant attention across diverse fields. Considering the inherent binding affinity between MOFs and HOFs along with the fact that many MOF linkers can serve as building blocks for constructing HOFs, their combination holds promise in creating functional materials with enhanced performance. This feature paper provides an introduction to the interconversion between MOFs and HOFs followed by highlighting the emerging applications of MOF-HOF composites. Finally, we briefly discuss the current challenges associated with future perspectives on MOF-HOF composites.

A novel composite electrode with multiple pore structures for efficient treatment of heavy metal ions in capacitive deionization

Multiple porous carbon materials have great promise and potential in the capacitive deionization (CDI) field. Specific surface area (SSA), pore size distribution, and preparation method of CDI electrode materials are essential for the treatment of heavy metal ions. In this work, PPy composited porous carbon electrodes (hypercrosslinked polymers/polypyrrole, HCPs/PPy) were obtained by one-step crosslinked carbonization preparation and electro-deposition. The diverse pore structure gives the composite electrode a large SSA and excellent adsorption performance. HCPs/PPy-4 gives a high SSA of 251.26 m2/g. In the CDI process, the adsorption capacity of HCPs/PPy-4 for Fe3+, Cu2+, Pb2+, and Ag+ is 20.69 mg/g, 37.81 mg/g, 26.86 mg/g, and 40.95 mg/g. The negative electrode recoveries for the adsorption of the four ions were reached 81.2%, 89.2%, 85.5%, and 100%, respectively. It indicates that HCPs/PPy is a novel and potentially porous carbon electrode for high-performance CDI.

Carbon/copper oxide electrode materials with high atomic utilization constructed by in-situ induced growth strategy of nano metal-organic frameworks

Carbon/metal composites derived from metal-organic frameworks (MOFs) have attracted widespread attention due to their excellent electronic conductivity, adjustable porosity, and outstanding stability. However, traditional synthesis methods are limited by the dense stereo geometry and large crystal grain size of MOFs, resulting in many metals active sites are buried in the carbon matrix. While the common strategy involves incorporating additional dispersed media into material, this leads to a decrease in practical metal content. In this study, nanosized copper-metal-organic frameworks (Cu-MOFs) are in-situ grown on surface of carbon spheres by pre-anchoring copper ions, and the hybrid composite of porous carbon/copper oxide with high copper atom utilization rate is prepared through activation and pyrolysis methods. This strategy effectively addresses the issue of insufficient exposure of metal sites, and the obtained composite material exhibits high effective copper atom utilization rate, large specific surface area (2052.3 m2·g−1), diverse pore structure, outstanding specific capacity (1076.5F·g−1 at 0.5 A·g−1), and excellent cycle stability. Furthermore, this highly atom-economical universal method has positive significance in application fields of catalysis, energy storage, and adsorption.

Flow unit classification and characterization with emphasis on the clustering methods: a case study in a highly heterogeneous carbonate reservoir, eastern margin of Dezful Embayment, SW Iran

Previous attempts to classify flow units in Iranian carbonate reservoirs, based on porosity and permeability, have faced challenges in correlating the rock's pore size distribution with the capillary pressure profile. The innovation of this study highlights the role of clustering techniques, such as Discrete Rock Type, Probability, Global Hydraulic Element, and Winland's Standard Chart in enhancing the reservoir's rock categorization. These techniques are integrated with established flow unit classification methods. They include Lucia, FZI, FZI*, Winland R35, and the improved stratigraphic modified Lorenz plot. The research accurately links diverse pore geometries to characteristic capillary pressure profiles, addressing heterogeneity in intricate reservoirs. The findings indicate that clustering methods can identify specific flow units, but do not significantly improve their classification. The effectiveness of these techniques varies depending on the flow unit classification method employed. For instance, probability-based methods yield surpassing results for low-porosity rocks when utilizing the FZI* approach. The discrete technique generates the highest number of flow unit classes but provides the worst result. Not all clustering techniques reveal discernible advantages when integrated with the FZI method. In the second part, the study creatively suggests that rock classification can be achieved by concurrently clustering irreducible water saturation (SWIR) and porosity in unsuccessful flow unit delineation cases. The SWIR log was estimated by establishing a smart correlation between porosity and SWIR in the pay zone, where water saturation and SWIR match. Then, the estimated saturation was dispersed throughout the reservoir. Subsequently, the neural network technique was employed to cluster and propagate the three finalized flow units. This methodology is an effective recommendation when conventional flow unit methods fail. The study also investigates influential factors causing the failure of flow unit classification methods, including pore geometry, oil wettability, and saturation in heterogeneous reservoirs.

Classification of rock types of porous limestone reservoirs: case study of the A oilfield

Rock types with similar lithological components and pore structures form the basic units of porous limestone reservoirs; this influences the reservoir evaluation efficiency and water injection development. As the main oil and gas pay zone in central Iraq, the Cretaceous Khasib Formation reservoirs are influenced by deposition, dissolution, and cementation. There is strong vertical heterogeneity in the most important zone of the Kh2 layer, with diverse rock types and complex pore structures. Based on core observation and casting thin-section identification, the Kh2 layer in the study area was divided into eight lithofacies types as argillaceous bioclastic wackestone, planktic foraminiferium wackestone, lamellar bioclastic wackestone, intraclastic–bioclastic packstone, patchy green algae packstone, green algae and pelletoid packstone, benthic foraminiferium–bioclastic packstone, and intraclastic grainstone. Along with the reservoir void space types of the lithofacies, capillary pressure curves are used to quantitatively analyze the throat and pore features of the different lithofacies. From the porosity–permeability cross-plot characteristics and distribution of pore types, 14 petrophysical facies are obtained. Finally, based on the differences between the lithofacies and petrophysical facies, the Kh2 member is divided into 13 rock types with different geological origins and petrophysical characteristics. Among these, the rock type RT1-8-14 has the best and rock type RT1-1-1 has the worst physical properties among the reservoir rock types. This study provides an optimization method for carbonate reservoir evaluation and is expected to be beneficial for efficient development of similar carbonate reservoirs.

Characterization of brittleness index of gas shale and its influence on favorable block exploitation in southwest China

The microstructure, mineral composition, total organic carbon content, etc., of gas shale are crucial parameters for shale reservoirs, which can directly/indirectly affect shale brittleness, fracturing effect, adsorption ability and production efficiency. The study proposed a workflow to characterize the physical and mechanical parameters of Lower Silurian Longmaxi shale outcrop samples extracted from the favorable block in Changning, Sichuan, southwest China. This study elaborated on the influence of these physical and mechanical characteristics and proposed a corresponding brittleness index on shale extraction. In addition, it put forward corresponding suggestions for development and risk control. For a better understanding the mechanisms of shale gas storage and production, XRD, XRF, SEM, low temperature Nitrogen adsorption method, nuclear magnetic resonance and other measurements were employed to analyze and study the mineral composition, microstructure, and adsorption performance of shale. The results demonstrated that the pores of shale are mainly slit pores; there are diverse pore types in shale, mainly including intergranular pores, mineral particle dissolution pores, and internal pores of organic matter; The samples with relatively low porosity also noticeably exhibit ultra-low permeability, and the nanopore structure is remarkably significant, with distribution primarily in range of 5–237 nm. Finally, a brittleness index considering the influence of water content and the mechanical properties was proposed, and the coupling interaction of various minerals components and mechanical properties on the brittleness index can more objectively reflect the brittleness characteristics of deep shale formation.

Luminescent carbon dots encapsulating in Eu3+ doped gahnite spinel nanocomposite for boosting thermal sensing, advanced level III detection and intelligent anti-counterfeiting applications

The exceptional optical properties of carbon dots (CDs) position them as a highly promising category of multifunctional carbon-based nanomaterials. When hydrothermally prepared CDs are incorporated into europium-doped zinc aluminate ZnAl2O4 nanophosphors (ZAO:Eu3+ NPs) synthesized via ultrasonication method, the resulting CDs@ZAO:Eu3+ nanocomposite (NCs) exhibits a broad excitation band, with a prominent peak at approximately 393 nm, perfectly matching the emission wavelength range (500–750 nm) of near-ultraviolet (n-UV) LED chips. Significantly, the CDs (5 wt %)@ZAO:Eu3+ NCs exhibit a remarkable 12.5 folds enhancement in photoluminescence (PL) intensity compared to ZAO:Eu3+ alone, thanks to the Förster Resonance Energy Transfer (FRET) between CDs and Eu3+ ions. This enhancement in luminescence could stem from the CDs capturing electrons and facilitating energy transfer to the luminescent Eu3+ ions. Utilizing CDs to enhance fluorescence presents a straightforward and eco-friendly approach for boosting luminescence properties. Impressively, even under elevated temperatures reaching 420 K, the thermal stability of CDs (5 wt %)@ZAO:Eu3+ NCs remains outstanding, retaining 90 % of its initial luminescence intensity. This highlights its exceptional thermal stability, characterized by a high activation energy of 0.27 eV. With an impressive internal quantum efficiency (IQE) of 87.01 %, the optimized composite also achieves remarkable colour purity (CP), reaching 99.5 %. The relative sensitivity was 1.36 %, at 300 K. Thus, CDs@ZAO:Eu3+ is a promising material for non-contact optical thermometry applications. Utilizing the optimized NCs through a simple powder dusting technique effectively develops latent fingerprints (LFPs) on various surfaces, revealing fingerprints (FPs) under 365 nm UV light. Additionally, the study investigates diverse pore parameters including number, position, size, shape, and inter-spacing. Furthermore, optimized NCs are utilized to create a transparent anti-counterfeiting (AC) ink, offering effective AC features through its red emission under 365 nm UV light.

Reservoir Rock Discrimination Based on Integrated Image Logs and Petrographic Analysis: A Case Study from the Early Miocene Nukhul Carbonate, Southern Gulf of Suez, Egypt

AbstractThe discrimination of rock types within the limestones and dolostones of the Nukhul Formation in the West Younis Field (Gulf of Suez Basin, Egypt) presents significant challenges due to their multi-scale compositional and diagenetic heterogeneity, diverse pore types, complex microstructures, and limited core data. This study aims to characterize the carbonate reservoir of the Early Miocene sediments and establish distinct reservoir rock types by employing textural analysis, geological interpretations (i.e., structural interpretation, fracture analysis, reservoir characteristics) using advanced imaging tools, and petrophysical measurements to model porosity/permeability profiles across the reservoir. A new dataset was obtained from the latest exploratory well in the West Younis Field, incorporating microresistivity and acoustic image logs, well logs, nuclear magnetic resonance (NMR) tools, and drill cutting petrographic analysis. The integration of these datasets provided a comprehensive understanding of the properties of the Early Miocene carbonate reservoir. Based on image logs, the carbonate facies were divided into four reservoir units. Petrographic evaluation further classified two facies (A and B) based on diagenetic factors controlling reservoir quality. The results revealed the occurrence of multiple phases of dolomitization, which influenced the reservoir quality. Early-stage dolomitization enhanced reservoir quality, while late-stage idiotopic dolomite crystal growth diminished it. The study also provided comprehensive information on the original rock fabric/texture, diagenetic processes, porosity types and origins, as well as the spatial distribution of pores (permeability index) within this complex carbonate reservoir. By employing an integrated technique, this study successfully differentiated the carbonate reservoir into distinct rock types, leading to improved reservoir characterization and field development. Additionally, the findings contribute valuable insights for the development and exploration of the Early Miocene carbonate section in the southern Gulf of Suez.

Two new members of the covalent organic frameworks family: Crystalline 2D-oxocarbon and 3D-borocarbon structures

Oxocarbons, known for over two centuries, have recently revealed a long-awaited facet: two-dimensional crystalline structures. Employing an intelligent global optimization algorithm (IGOA) alongside density-functional calculations, we unearthed a quasi-flat oxocarbon (C6O6), featuring an oxygen-decorated hole, and a novel 3D-borocarbon. Comparative analyses with recently synthesized isostructures, such as 2D-porous carbon nitride (C6N6) and 2D-porous boroxine (B6O6), highlight the unique attributes of these compounds. All structures share a common stoichiometry of X6Y6 (which we call COF-66), where X = B, C, and Y = B, N, O (with X ≠ Y), exhibiting a 2D-crystalline structure, except for borocarbon C6B6, which forms a 3D crystal. In our comprehensive study, we conducted a detailed exploration of the electronic structure of X6Y6 compounds, scrutinizing their thermodynamic properties and systematically evaluating phonon stability criteria. With expansive surface areas, diverse pore sizes, biocompatibility, π-conjugation, and distinctive photoelectric properties, these structures, belonging to the covalent organic framework (COF) family, present enticing prospects for fundamental research and hold potential for biosensing applications.

Design and synthesis of different sized polyhedral channel MOF materials for the separation of CO2/N2

A fractal polyhedral pore structural MOFs (Cu-TATB) is synthesized from the coordination of tridentate ligands (H3TATB) and Cu4 clusters. This material is characterized by single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis. The structure contains two different pore structures, including closed octahedral cages and open tetrakaidecahedron cages. The material has been successfully utilized for the separation of CO2/N2 due to the fractal structure of the channel with different pore sizes. Under optimized temperature, Cu-TATB adsorbed a large amount of CO2 and only negligible amount of N2, and the selectivity reaches 27. Breakthrough experiments demonstrated that this material can efficiently separate N2 and CO2. This structure further demonstrates the infinite potential of 3D MOFs with diverse pore structures in applications such as CO2 adsorption and separation.

Investigating the adsorption potential of char derived from waste latex for methylene blue removal

This study presents the adsorption of methylene blue (MB) dye using latex char derived from pyrolysis of latex gloves. The adsorption process was investigated systematically using Response Surface Methodology (RSM) with a Central Composite Design (CCD). The effects of four key variables, namely pH, time, temperature, and adsorbent dosage, were studied using a factorial design enriched with center points and axial points. Experimental data were analyzed using a second-order polynomial regression model to construct a response surface model, which elucidated the relationship between the variables and MB removal efficiency. The study found that the char obtained at 800 °C exhibited the highest adsorption capacity due to its increased carbonization, expanded surface area, and diverse pore structure. Analysis of Variance (ANOVA) confirmed the significance of the quadratic model, with remarkable agreement between predicted and experimental outcomes. Diagnostic plots validated the model's reliability, while 3D contour graphs illustrated the combined effects of variables on MB removal efficiency. Optimization using DoE software identified optimal conditions resulting in a 99% removal efficiency, which closely matched experimental results. Additionally, adsorption isotherms revealed that the Freundlich model best described the adsorption behavior, indicating heterogeneous surface adsorption with multilayer adsorption. This comprehensive study provides valuable insights into the adsorption process of MB dye using latex char, with implications for wastewater treatment and environmental remediation.

Study on the Temperature and Water Distribution of Hot Air in Red Loam Based on Soil Continuous Cropping Obstacles

In recent years, the problematic circumstances of the constant cropping problem in facility crops have become increasingly serious. Compared to chemical disinfection, soil steam disinfestation offers the benefits of environmental protection and being pollution-free, which can effectively reduce the problem of constant cropping in crops. However, during the steam disinfection procedure, a large quantity of liquid water is formed due to the condensation of high-temperature steam, which causes soil pore blockage, seriously affecting the mass and heat transfer efficacy of steam and, thus, affecting the disinfection efficiency. Therefore, to solve this problem, this paper proposes the use of hot air dehumidification to remove excess water from soil pores and achieve the goal of dredging the pores. However, further exploration is needed on how to efficiently remove excess water from different pore structures through hot air applications. Therefore, this paper first used CFD simulation technology to simulate and analyze the hot air flow field, mass, and heat transfer in soil aggregates of different sizes (<2 mm to >8 mm). Then, based on the soil hot air heating experimental platform, research was conducted on the mass and heat transfer mechanism of hot air under diverse soil pore conditions. The results show that as the soil particle size increases from <2 mm to >8 mm, the number of soil macropores also increases, which makes the soil prone to the formation of macropore thermal currents, and the efficiency of hot air heating for dehumidification first increases and then decreases. Among them, the 4–6 mm treatment has the best dehumidification effect through hot air heating, with a deep soil temperature of up to 90 °C and a water content reduction of 6%. The 4–6 mm treatment has a high-temperature heating and dehumidification area of 15–20 cm deep. The above results lay the theoretical foundations for the parameters of hot air heating and dehumidification operations, as well as the placement of the hot air pipe. This paper aims to combine hot air dehumidification technology, for the removal of excess water from soil, and dredging soil pores, ultimately achieving the goal of improving soil steam disinfection efficiency.

Towards optimal 3D battery electrode architecture: Integrating structural engineering with AI-driven optimization

The rapid evolution of energy storage devices, driven by increasing demands for prolonged battery life in electronics as well as sustainable energy solutions has elevated lithium-ion batteries (LIBs) to prominence in modern energy systems. With electric vehicle sales and LIB demand surging, the need for high-performing batteries is at an all-time high. However, critical issues with LIBs have become apparent, particularly in energy degradation due to poor mass transport, emphasising the need for advancements in electrode design. This review explores the influence of electrode structural factors on mass transport properties, with a specific focus on the latest developments in three-dimensional (3D) battery electrodes featuring diverse pore arrangements—ranging from random to ordered pores or porosity gradients. The review delves into recent breakthroughs achieved through structural diversification by applying an inverse design to Proximity-field nanoPatterning (PnP), laying the groundwork for collaborative efforts aimed at advancing energy storage technologies. Various fabrication methods for 3D electrodes are discussed, highlighting the promising role of integrating the PnP technique with computational algorithms to enhance the precision and design capabilities of 3D nanostructures.

Microscopic pore-throat structure variability in low-permeability sandstone reservoirs and its impact on water-flooding efficacy: Insights from the Chang 8 reservoir in the Maling Oilfield, Ordos Basin, China

The Chang 8 reservoir of the Maling Oilfield in the Ordos Basin, China is facing a series of challenges in hydrocarbon resource development, including rapidly decreasing production rates, declining dynamic fluid levels, and elevated water cuts in oil wells, along with heterogeneity in microscopic pore-throat structures and notable interstratal inconsistencies. To systematically address these issues, this study selected representative samples from the reservoir and conducted rigorous microscopic percolation experiments on them. A comprehensive evaluation of the heterogeneity in microscopic pore structures was conducted using an integrative methodological approach, involving physical property quantification, petrographic thin-section analysis, scanning electron microscopy, constant-rate mercury intrusion, and nuclear magnetic resonance techniques. The primary objective of this investigation is to elucidate the underlying formation mechanisms, states of occurrence, and spatial distributions of residual oil. Understanding of these issues will facilitate the establishment of empirical correlations between diverse microscopic pore structures and water-flooding efficiencies, and aid in the identification of key variables governing the distribution of residual oil. Analytical outcomes reveal substantial variations in seepage characteristics contingent upon the nature of microscopic seepage conduits. Specifically, the Chang 8 reservoir manifests four discernible categories of microscopic seepage pathways: solely intergranular pores, a confluence of dissolution and intergranular pores, exclusively dissolution pores, and micropores. A correlative decline in oil displacement efficiency is observed across these conduit types. Critical variables such as throat radius and its distribution patterns emerge as pivotal determinants influencing oil displacement efficiency, eclipsing the impact of conventional physical properties and mobile fluid saturation levels. Remarkably, samples characterized by a composite of dissolution and intergranular pores demonstrate superior displacement efficiency. Distinct types of pore structures correspond to noticeably different water-flooding oil pathways and oil displacement efficiencies. During the water-flooding process, fingering network displacement is dominant, and it exerts a significant control on oil displacement efficiency. Key factors affecting this efficiency include the injected water volume multiples and displacement pressure, values of which should be optimized during the actual water-flooding process.

Construction of imide‐linked covalent organic frameworks with palladium nanoparticles for oxygen reduction reaction

AbstractCovalent organic frameworks (COFs) have been widely employed as electrocatalysts for oxygen reduction reaction (ORR) due to their diverse and tunable skeletons and pores. However, their electrocatalytic activity was limited due to the lack of highly active catalytic sites. In this work, we have first immobilized palladium nanoparticles (NPs) into the crystal, porous, and stable imide‐linked COF for ORR. The newly designed COF had pyridine linkers with imide‐linkages in the frameworks serving as the binding sites to anchor Pd sites, and the high surface area and open pore channels provide fast mass transport pathway to the active Pd sites, which contributed highly active performance in ORR. And the designed catalyst delivered onset potential and the half‐wave potential of COF‐Pd of 0.97 and 0.83 V, with a limited current density of 6.1 mA cm−2, respectively. This work provides us insights into developing high crystalline COFs with metal NPs in electrocatalytic systems.

2D Conjugated Metal-Organic Frameworks: Defined Synthesis and Tailor-Made Functions.

Conspectus2D conjugated metal-organic frameworks (2D -MOFs) have emerged as a class of graphene-like materials with fully π-conjugated aromatic structures. Their unique structural characteristics provide abundant physiochemical features, including regular nanochannels, high electrical conductivity, and customizable band gaps. Recent intensive research has significantly advanced this field, yet the exploration of 2D c-MOFs with enhanced features is limited by the availability of organic linkages and topologies. Designing novel ligands is essential for the construction of new 2D c-MOFs with high crystallinity, excellent conductivity, and tailor-made functions.In this Account, we summarize our recent contributions in fine-tuning the topology of 2D c-MOFs through precise ligand design, thereby giving them fantastic structures and tailor-made functions. First, we propose the concept of replacing planar ligands by nonplanar ligands on conductive MOF skeletons. The incorporation of nonplanar ligands improves the solubility of large π-conjugated organic molecules without interfering with the interlayer π-stacking. Our investigation discovered that conjugate polycyclic aromatics-based ligands can be synthesized through in situ Scholl reactions by means of oxidative cyclodehydrogenation of a nonplanar precursor ligand during the solvothermal synthesis process. Hence, fully conjugated 2D c-MOFs can be directly synthesized from nonplanar organic ligands, simplifying and diversifying the preparation of 2D c-MOFs. Accordingly, the design flexibility of the ligands expands the topological structures and pore types. By controlling the synthesis conditions, we can successfully induce either a rhombus or a kagome topology from a nonplanar D2 symmetric ligand. Moreover, by employing a ligand engineering strategy, we incrementally increase the number of coordination functional groups on a twisted hexabenzocoronene core, resulting in the formation of three distinct symmetric hydroxyl ligands. These ligands elicit diverse target topologies and pore sizes, resulting in variances in the coordination node density on the skeletons. This, in turn, leads to differences in electron transfer abilities, ultimately causing variations in the electrical conductivity and mobility. In addition, we employ a straightforward coupling method to incorporate redox components, such as salphen and pyrazine, into nonplanar ligands, facilitating the synthesis of 2D c-MOFs with highly active centers. This strategy confers upon the resulting frameworks substantial capacity for catalysis and energy storage, offering a good platform for elucidating the structure-property relationships at the molecular level. Moreover, the well-defined synthesis of 2D c-MOFs imparts them with specific properties, particularly in the fields of electrical, electrochemical, and spintronic applications. At the end, the primary challenges facing 2D c-MOFs in achieving tailor functions and their practical applications are proposed. This account is expected to evoke new inspirations and innovative research in the field of 2D c-MOFs, especially in emerging interdisciplinary research areas.