Fabrication of carbon nanorods and graphene nanoribbons from a metal–organic framework

Metal-organic framework derived crystalline nanocarbon for Fenton-like reaction

Nanoporous carbons with tailorable nanoscale texture and long-range ordered structure are promising candidates for energy, environmental and catalytic applications, while the current synthetic methods do not allow elaborate control of local structure. Here we report a salt-assisted strategy to obtain crystalline nanocarbon from direct carbonization of metal-organic frameworks (MOFs). The crystalline product maintains a highly ordered two-dimensional (2D) stacking mode and substantially differs from the traditional weakly ordered patterns of nanoporous carbons upon high-temperature pyrolysis. The MOF-derived crystalline nanocarbon (MCC) comes with a high level of nitrogen and oxygen terminating the 2D layers and shows an impressive performance as a carbocatalyst in Fenton-like reaction for water purification. The successful preparation of MCC illustrates the possibility to discover other crystalline heteroatom-doped carbon phases starting from correctly designed organic precursors and appropriate templating reactions.

Enhanced Free Li-Ion Mobility in Solid-State Electrolytes via Long-Range Assembly of Porous Materials

Metal-organic frameworks (MOFs), with their tunable pore sizes and high surface areas, are gaining prominence in Li metal battery applications, including their use as nanofillers in solid composite electrolytes (SCEs) for enhanced ionic conductivity. Yet, when used in SCEs, individual dispersed MOF particles in isolation as nanofillers can impede efficient ion transport in all-solid-state batteries due to the insufficient supply of ionic transport pathways within SCEs. Here, we introduced a continuous SCE nanofiller with long-range assembly interconnected porous MOFs (IMOF_SCE) for effective ion transport pathway supply along the interface between the nanofiller and the polymer matrix. IMOF_SCE achieved Li-ion conductivity (6.72 × 10-5 S cm-1 at 20 °C) and Li-ion transference number (tLi+ = 0.855), resulting in the improved electrochemical performance of Li metal batteries. Additionally, the Li/LiFePO4 full cell integrated with IMOF_SCE achieved an outstanding stable capacity retention of 98.8% in 300 cycles. This work offers insights into the design strategy of effective nanofillers for SCEs and can be adapted for other porous materials.

Superlong Metal-Organic Framework Micro-/Nanofibers for Selective Vitamin Absorption

Superlong MOF-74-type micro/nanofibers, which have aspect ratios much higher than 200, are synthesized via nanoparticulate MOF-mediated recrystallization. Co-MOF-74 microfibers have high crystallinity, whereas Co-MOF-74-II nanofibers are composed of nanocrystals and amorphous phases, even though they have nanofibrous morphology. Both MOFs consist of plenty of micropores with diameters in the range of 1.0 to 2.0 nm, and they exhibit high thermal stability with a decomposition temperature higher than 260.0 °C. The MOFs are demonstrated for selective absorption of some vitamins including riboflavin, folic acid, and 5-methyltetrahydrofolate. Co-MOF-74-II nanofibers can efficiently absorb riboflavin and folic acid from their aqueous solution with absorption percentages approaching 90.0%, and they have enhanced capability for absorbing tocopherol in methanol. The micro/nanofibrous morphology, together with the capability for selective vitamin absorption, makes the novel MOFs highly promising for applications in micro-solid-phase extraction.

Synergistic N/Mn Codoping Deagglomerate Carbon Coating of LiFePO4/C To Boost Electrochemical Performance

LiFePO4 is widely used because of its high safety and cycle stability, but its inefficient electronic conductivity combined with sluggish Li+ diffusivity restricts its performance. To overcome this obstacle, applying a layer of conductive carbon onto the surface of LiFePO4 has the greatest improvement in electronic conductivity and Li+ diffusivity. However, the rate performance of carbon-coated LiFePO4 makes it difficult to meet the application requirements. Although nitrogen doping improves electrochemical performance by providing active sites and electronic conductivity, the N-doped carbon coating is prone to agglomeration, which causes a sharp decrease in capacity when the current rate increases. In this work, a synergistic N, Mn codoping strategy is implemented to overcome the aforementioned drawbacks by disrupting the large agglomeration of C-N bonds, improving the uniformity of the surface coating layer to enhance the completeness of the conductive network and increasing the number of Li+ diffusion channels, and thus accelerating the mass transfer rate under high-rate current. Consequently, this strategy effectively improves the rate capability (119 mA h g-1 at 10 C) while maintaining excellent cycling performance (88% capacity retention over 600 cycles at 5 C). This work improves the rate of ion diffusion and the rate capability of micrometer-sized LiFePO4, thus, enabling its wider application.

Stöber method to amorphous metal-organic frameworks and coordination polymers

The Stöber method is a widely-used sol-gel route for synthesizing amorphous SiO2 colloids and conformal coatings. However, the material systems compatible with this method are still limited. Herein, we have extended the approach to metal-organic frameworks (MOFs) and coordination polymers (CPs) by mimicking the Stöber method. We introduce a general synthesis route to amorphous MOFs or CPs by making use of a base-vapor diffusion method, which allows to precisely control the growth kinetics. Twenty-four different amorphous CPs colloids were successfully synthesized by selecting 12 metal ions and 17 organic ligands. Moreover, by introducing functional nanoparticles (NPs), a conformal amorphous MOFs coating with controllable thickness can be grown on NPs to form core-shell colloids. The versatility of this amorphous coating technology was demonstrated by synthesizing over 100 core-shell composites from 20 amorphous CPs shells and over 30 different NPs. Besides, various multifunctional nanostructures, such as conformal yolk-amorphous MOF shell, core@metal oxides, and core@carbon, can be obtained through one-step transformation of the core@amorphous MOFs. This work significantly enriches the Stöber method and introduces a platform, enabling the systematic design of colloids exhibiting different level of functionality and complexity.

Preparation of an aqueous zinc ion rGH/V2O5 photorechargeable supercapacitor

A photorechargeable supercapacitor was constructed using vanadium pentoxide (V2O5), reduced graphene oxide hydrogel (rGH), and zinc trifluoromethanesulfonate (Zn(CF3SO3)2) as the photoanode, cathode, and electrolyte, respectively. The phase composition, microstructure, chemical structure, light absorption, and specific surface area of the synthesized products and the electrochemical performance of the rGH/V2O5 supercapacitor were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-Vis spectroscopy, the Brunauer-Emmett-Teller (BET) method, and an electrochemical workstation, respectively. The results show that the device has a specific capacity of 164 F g-1 at 0.5 A g-1 under illumination with 95 mW cm-2 light intensity, which is 20.5% higher than that under normal electrical charging. The supercapacitor has a 75% capacity retention rate and 100% coulombic efficiency, respectively, after 10 000 testing cycles under photoelectric synergistic charging and discharging. The as-constructed rGH/V2O5 photorechargeable supercapacitor exhibits promising application potential in electric vehicles and wearable electronics.

Imidacloprid removal by modified graphitic biochar with Fe/Zn bimetallic oxides

Coping with the critical challenge of imidacloprid (IMI) contamination in sewage treatment and farmland drainage purification, this study presents a pioneering development of an advanced modified graphitic white melon seed shells biochar (Fe/Zn@WBC). The Fe/Zn@WBC demonstrates a substantial enhancement in adsorption efficiency for IMI, achieving a remarkable removal rate of 87.69% within 30 min and a significantly higher initial adsorption rate parameter h = 4.176 mg g-1·min-1. This significant improvement outperforms WBC (12.22%, h = 0.115 mg g-1·min-1) and highlights the influence of optimized adsorption conditions at 900 °C and the graphitization degree resulting from Fe/Zn bimetallic oxide modification. Characterization analysis and batch sorption experiments including kinetics, isotherms, thermodynamics and pH factors illustrate that chemical adsorption is the main type of adsorption mechanism responsible for this superior ability to remove IMI through pore filling, hydrogen bonding, hydrophobic interaction, electrostatics interaction, π-π interactions as well as complexation processes. Furthermore, we demonstrate exceptional stability of Fe/Zn@WBC across a broad pH range (pH = 3-11), co-existing ions presence along with humic acid under various real water conditions while maintaining high removal efficiency. This study presents an advanced biochar adsorbent, Fe/Zn@WBC, with efficient adsorption capacity and easy preparation. Through three regeneration cycles via pyrolysis method, it demonstrates excellent pyrolysis regeneration capabilities with an average removal efficiency of 92.02%. The magnetic properties enable rapid separation facilitated by magnetic analysis. By elucidating the efficacy and mechanistic foundations of Fe/Zn@WBC, this research significantly contributes to the field of environmental remediation by providing a scalable solution for IMI removal and enhancing scientific understanding of bimetallic oxides-hydrophilic organic pollutant interactions.

Hydrogenation of Furfural over Biomass-Based Electron-Deficient Co-NC Nanotube Catalyst

The conversion of furfural to furfuryl alcohol is one of the most significant reactions from industrial-scale produced biomass platform molecules to value-added chemicals. In this work, biomass-based chitosan was used as both a carbon source and nitrogen source to synthesize nitrogen-doped carbon. With the addition of cobalt, the optimized 7.5Co-NC-900 catalyst had the largest surface area and the graphite nanotube structure with the least defects. It was employed for the hydrogenation of furfural to furfuryl alcohol and reached a nearly full conversion and an equivalent yield at 130 °C in 4 MPa initial H2. The structure-function relationship study indicated that the N could interact with the neighbor Co in this catalyst and formed an electron-deficient Co center which was in favor of the adsorption of furfural in the nanotube and had high catalytic activity. The interactions between Co and N stabilized the catalyst so that it could remain stable in five runs of catalytic reactions.

Promising CO2 Capture and Effective Iodine Adsorption of Hyper-Cross-Linked Conjugated Porous Organic Polymers Prepared from a Cyclopentannulation Reaction

Three novel conjugated porous organic polymers, denoted as C-POP1-3 and which consist of alternating pyrene cores with various contorted fluorene surrogates, were successfully synthesized from a versatile one-pot palladium-catalyzed [3+2] cyclocondensation reaction. The resulting polymers were obtained in excellent yields and displayed weight-average molecular weights (Mw) ranging from 12.2 to 20.2 kg/mol with polydispersity indices (Mw/Mn) ranging between 1.8 and 2.4, suggesting that the molecular masses are narrowly distributed and thus implying homogeneous polymer chains. Thermal stability exploration of C-POP1-3 by thermogravimetric analysis (TGA) revealed an impressive robustness with a 10% weight reduction temperature attaining 485 °C. Investigation of the inherent microporosity properties of C-POP1-3 via nitrogen adsorption experiments using Brunauer-Emmett-Teller (BET) theory discloses their surface areas which reach up to 560 m2 g-1 and pore volumes averaging 0.47 cm3 g-1. The target conjugated polymers were explored as adsorbents disclosing a maximum carbon dioxide adsorption of 83.0 mg g-1 at 273 K and low pressure for C-POP1, whereas iodine sorption tests portrayed prominent outcomes, notably for C-POP3 which proved to owe a strong affinity toward the hitherto mentioned halogen by achieving a maximum adsorption of 2220 mg g-1. Additionally, recyclability experiments confirmed the possibility to regenerate the polymers' adsorption capabilities even after seven consecutive cycles of adsorption-desorption cycles, which qualify them as auspicious iodine adsorbents.

Facile Fabrication of Hollow Nanoporous Carbon Architectures by Controlling MOF Crystalline Inhomogeneity for Ultra-Stable Na-Ion Storage

Hollow nanoporous carbon architectures (HNCs) present significant utilitarian value for a wide variety of applications. Facile and efficient preparation of HNCs has long been pursued but still remains challenging. Herein, we for the first time demonstrate that single-component metal-organic frameworks (MOFs) crystals, rather than the widely reported hybrid ones which necessitate tedious operations for preparation, could enable the facile and versatile syntheses of functional HNCs. By controlling the growth kinetics, the MOFs crystals (STU-1) are readily engineered into different shapes with designated styles of crystalline inhomogeneity. A subsequent one-step pyrolysis of these MOFs with intraparticle difference can induce a simultaneous self-hollowing and carbonization process, thereby producing various functional HNCs including yolk-shell polyhedrons, hollow microspheres, mesoporous architectures, and superstructures. Superior to the existing methods, this synthetic strategy relies only on the complex nature of single-component MOFs crystals without involving tedious operations like coating, etching, or ligand exchange, making it convenient, efficient, and easy to scale up. An ultra-stable Na-ion battery anode is demonstrated by the HNCs with extraordinary cyclability (93 % capacity retention over 8000 cycles), highlighting a high level of functionality of the HNCs.

Noncovalent Functionalization of Graphene Nanoplatelets and Their Applications in Supercapacitors

We demonstrate a simple noncovalent functionalization technique, which involves graphite exfoliation and subsequent coating of the resulting graphene nanoplatelets (GNPs) with trimellitic anhydride (TMA), using a thermomechanical exfoliation process. TMA adsorbs on the surface of the GNPs, resulting in a reduction of the specific surface area to 312 ± 9 m2/g compared to 410 ± 12 m2/g for the unmodified GNPs. Detailed imaging, thermogravimetric, and X-ray diffraction analysis showed that the modified GNPs (TMA-GNPs) maintain similar structure to the unmodified GNPs. The presence of functional groups, confirmed by X-ray photoelectron spectroscopy analysis, caused an increase in the surface energy from 45.6 mJ/m2 for the GNPs to 57.9 mJ/m2 for TMA-GNPs. The resulting coated TMA-GNPs form stable dispersions in water while maintaining their inherent conductive properties, thus enabling applications, such as the manufacture of conductive films and supercapacitors. As a proof-of-concept, electrodes for supercapacitors are prepared from concentrated aqueous dispersions of the functionalized GNPs. Electrochemical characterization of the supercapacitors using electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge/discharge tests showed a specific capacitance of 22.2 F/cm3 at a scan rate of 1 mV/s from cyclic voltammetry and 17.3 F/cm3 at a current density of 1 A/g from galvanostatic charge/discharge tests, with a 90% capacitance retention after 10,000 cycles.

Hybrid and Asymmetric Supercapacitors: Achieving Balanced Stored Charge across Electrode Materials

An electrochemical capacitor configuration extends its operational potential window by leveraging diverse charge storage mechanisms on the positive and negative electrodes. Beyond harnessing capacitive, pseudocapacitive, or Faradaic energy storage mechanisms and enhancing electrochemical performance at high rates, achieving a balance of stored charge across electrodes poses a significant challenge over a wide range of charge-discharge currents or sweep rates. Consequently, fabricating hybrid and asymmetric supercapacitors demands precise electrochemical evaluations of electrode materials and the development of a reliable methodology. This work provides an overview of fundamental aspects related to charge-storage mechanisms and electrochemical methods, aiming to discern the contribution of each process. Subsequently, the electrochemical properties, including the working potential windows, rate capability profiles, and stabilities, of various families of electrode materials are explored. It is then demonstrated, how charge balancing between electrodes falters across a broad range of charge-discharge currents or sweep rates. Finally, a methodology for achieving charge balance in hybrid and asymmetric supercapacitors is proposed, outlining multiple conditions dependent on loaded mass and charge-discharge current. Two step-by-step tutorials and model examples for applying this methodology are also provided. The proposed methodology is anticipated to stimulate continued dialogue among researchers, fostering advancements in achieving stable and high-performance supercapacitor devices.

Exceptional piezocatalytic H2 production of nitrogen-doped TiO2@carbon nanosheets induced by engineered piezoelectricity

Piezocatalytic hydrogen evolution is a promising strategy to generate sustainable energy. In this report, nitrogen-doped (N-doped) TiO2@ carbon nanosheets (N-TiO2@C NSs) was successfully synthesized using C3N4 as a multifunctional template. During the synthesis, the two-dimensional (2D) architecture of C3N4 nanosheets directed the synthesis of TiO2 nanosheets. In addition, nitrogens of C3N4 were doped into the TiO2 lattice. Simultaneously, C3N4 was transformed into N-doped carbon nanosheets. N doping broke the crystal symmetry of TiO2, which endowed TiO2 with promising piezoelectric properties. The N-doped carbon nanosheets derived from C3N4 improved charge carrier separation efficiency and served as a flexible support to inhibit structural damage under sonication. Therefore, the N-TiO2@C NSs exhibited highly efficient activity for piezocatalytic H2 production (6.4 mmol·g-1·h-1) in the presence of methanol, much higher than those of the previously reported piezocatalysts. Our method is hoped to provide a new strategy for designing highly efficient piezocatalysts.

Dual-Confinement Effect of Nanocages@Nanotubes Suppresses Polysulfide Shuttle Effect for High-Performance Lithium-Sulfur Batteries

The shuttle effect of lithium polysulfides (LiPSs) severely hinders the development and commercialization of lithium-sulfur batteries, and the design of high-conductive carbon fiber-host material has become a key solution to suppress the shuttle effect. In this work, a unique Co/CoN-carbon nanocages@TiO2-carbon nanotubes structure (NC@TiO2-CNTs) is constructed using an electrospinning and nitriding process. Lithium-sulfur batteries using NC@TiO2-CNTs as cathode host materials exhibit high sulfur utilization (1527 mAh g-1 at 0.2 C) and can still maintain a discharge capacity of 663 mAh g-1 at a high current density of 5 C, and the capacity loss is only 0.056% per cycle during 500 cycles at 1 C. It is worth noting that even under extreme conditions (sulfur-loading = 90%, surface-loading = 5.0 mg cm-2 (S), and E/S = 6.63 µL mg-1), the lithium-sulfur batteries can still provide a reversible capacity of 4 mAh cm-2. Throughdensity functional theory calculations, it has been found that the Co/CoN heterostructures can adsorb and catalyze LiPSs conversion effectively. Simultaneously, the TiO2 can adsorb LiPSs and transfer Li+ selectively, achieving dual confinement for the shuttle effect of LiPSs (nanocages and nanotubes). The new findings provide a new performance enhancement strategy for the commercialization of lithium-sulfur batteries.

Study of Zinc Diffusion Based on S, N-Codoped Honeycomb Carbon Cathodes for High-Performance Zinc-Ion Capacitors

Capacitors with zinc ions, with excellent stabilities, low cost, and high energy density, are expected to be promising energy storage devices. However, the development of zinc-ion capacitors is quietly restricted by low specific capacity and cycling stability. Herein, to overcome these limitations, honeycomb-structured S, N-codoped carbon (SNPC) is constructed by one-pot calcination of waste corn bracts and thiourea. The honeycomb structure of SNPC is demonstrated to provide abundant active sites that can enhance the extron/ion transport, conductivity for high power export, and ion adsorption capacity in energy storage applications, leading to a higher electrochemical performance achieved. The electrolytes of zinc salt have also been studied. It reveals that the SNPC electrode presents the best electrochemical performance in a 2 M ZnSO4 and 0.5 M ZnCl2 electrolyte mixture because in the electrolyte mixture, Cl- can replace the existing bound water in the solvation structure to form an anion-type water-free solvation structure ZnCl42-. The SNPC-800 electrode with a highly improved surface area (∼909.0 m2 g-1) is proved to be more suitable as the electrode than other materials. Aqueous zinc-ion capacitors (ZICs) have been assembled by the honeycomb-structured SNPC-800 as the cathode, which can achieve a relatively wide working voltage range of 0.1-1.8 V. The SNPC-800 ZICs exhibit a superior specific capacity of 179.1 mA h g-1 at 0.1 A g-1. The energy density of SNPC-800 ZICs reaches an impressive value of 89.6 Wh kg-1 at 53.8 W kg-1, and it sustains 28.3 Wh kg-1 at 1997.6 W kg-1. In addition, there is 99.8% capacity retention in the SNPC-800 ZICs over 5000 cycles. The absorption energy in SPNC is much higher than that in undoped CPC, as confirmed by density functional theory, which reveals that introducing of heteroatoms (S, N) has a comparatively active advantage at increasing the Zn-ion storage capacity. This work proposes a practical strategy for the effective recycling of waste biomass materials into honeycomb carbon electrode materials. Moreover, the honeycomb carbon-based ZICs with excellent electrochemical performance and long-term cycling stability possess great potential to be a superior cathode in practical applications.

Recent progress in electrode materials for micro-supercapacitors

Micro-supercapacitors (MSCs) stand out in the field of micro energy storage devices due to their high power density, long cycle life, and environmental friendliness. The key to improving the electrochemical performance of MSCs is the selection of appropriate electrode materials. To date, both the composition and structure of electrode materials in MSCs have become a hot research topic, and it is urgent to compose a review to highlight the most important research achievements, major challenges, opportunities, and encouraging perspectives in this field. In this review, research background of MSCs is first reviewed followed by their working principles, structural classifications, and physiochemical and electrochemical characterization techniques. Next, various materials and preparation methods are summarized, and the relationship between the MSC performance and structure and composition of materials are discussed in depth. Finally, this review provides a comprehensive suggestion on accelerating the development of electrode materials to facilitate the commercialization of MSCs.

A new and highly efficient CuMOF-based nanoenzyme and its application to the aptamer SERS/FL/RRS/Abs quadruple-mode analysis of ultratrace malachite green

Malachite green (MG) is highly toxic, persistent, and carcinogenic, and its widespread use is a danger to the ecosystem and a threat to public health and food safety, making it necessary to develop new sensitive multimode molecular spectroscopy methods. In this work, a new copper-based nanomaterial (CuNM) was prepared by a high-temperature roasting using a copper metal-organic framework (CuMOF) as precursor. The as-prepared CuNM was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, transmission electron microscopy (TEM), and BET surface area analysis. CuNM was found to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce the oxidation product TMBOX; however, subsequently, the MG aptamer (Apt) could be adsorbed on the CuNM surface by intermolecular interaction, which would inhibit the catalytic performance. After the addition of MG to be tested, the CuNM previously adsorbed by the Apt was transformed into its free state, thus restoring its catalytic activity. This new nanocatalytic indicator reaction could be monitored by surface-enhanced Raman scattering (SERS)/resonance Rayleigh scattering (RRS)/fluorescence (FL)/absorption (Abs) quadruple-mode methods. The SERS determination range was 0.004-0.4 nmol L-1 MG, with a limit of detection of 0.0032 nM. In this way, a rapid, stable, and sensitive method for the determination of MG residues in the environment was established.

Hollow Bowl NiS2 @polyaniline Conductive Linker/Graphene Conductive Network: A Triple Composite for High-Performance Supercapacitor Applications

The achievement of the outstanding theoretical capacitance of nickel sulfide (NiS2 ) is challenging due to its low conductivity, slow electrochemical kinetics, and poor structural stability. In this study, we utilize polyaniline (PANI) as a linker to anchor the NiS2 with a hollow bowl-like structure, uniformly dispersed at the surface of graphene oxide (GO)(NiS2 @15PG). The presence of PANI provides growth sites, resulting in a uniform and dense arrangement of NiS2 . This morphological modulation of NiS2 increases the contact area between the active material to electrolyte. Additionally, PANI effectively connects NiS2 with the conductive network of GO, which advances the electrical conductivity and ion diffusion properties. As a result, the Rct (charge transfer resistance) and Zw (Warburg impedance) of NiS2 @15PG decrease by 82.61 % and 66.76 % respectively. This unique structure confers NiS2 @15PG with high specific capacitance (536.13 C g-1 at 1 A g-1 ) and excellent multiplicative property of 60.93 % at 20 A g-1 . The assembled NiS2 @15PG//YP-50 supercapacitors (HSC) demonstrates an energy density (13.09 Wh kg-1 ) at a high-power density (16 kW kg-1 ). The capacity retention after 10,000 cycles at 5 A g-1 is 86.59 %, indicating its significant potential for practical applications.

Silver Metal-Organic Framework Derived N-Doped Carbon Nanofibers for CO2 Conversion into β-Oxopropylcarbamates

Developing efficient heterogeneous catalysts for chemical fixation of CO2 to produce high-value-added chemicals under mild conditions is highly desired but still challenging. Herein, we first reported an approach to prepare a novel catalyst (Ag@NCNFs), featuring Ag nanoparticles (NPs) embedded within porous nitrogen-doped carbon nanofibers (NCNFs), via growing a Ag metal-organic framework on one-dimensional electrospun nanofibers followed by pyrolysis. Benefiting from the abundant nitrogen species and porous structure, Ag NPs is well dispersed in the obtained Ag@NCNFs. Catalytic studies indicated that Ag@NCNFs exhibited excellent catalytic activity for the three-component coupling reaction of CO2, secondary amines, and propargylic alcohols to generate β-oxopropylcarbamates under mild conditions with a turnover number (TON) of 16.2, and it can be recycled and reused at least 5 times without an obvious decline in catalytic activity. The reaction mechanism was clearly clarified by FTIR, NMR, 13C isotope labeling, control experiments, and density functional theory calculations. The results suggest that Ag@NCNFs and 1,8-diazabicyclo[5.4.0]undec-7-ene can synergistically activate propargylic alcohol to react with CO2, and then the generated α-alkylidene cyclic carbonate was invaded by secondary amine to produce β-oxopropylcarbamate. Importantly, to the best of our knowledge, this is the first experimental and theoretical investigation on this reaction.

Ultrasensitive electrochemical sensing of catechol and hydroquinone via single-atom nanozyme anchored on MOF-derived porous carbon

Single-atom nanozymes (SANs) can significantly enhance the sensitivity and selectivity of electrochemical sensing platforms due to the homogeneity of their active sites, full atom utilization, and high catalytic activity. In this study, we demonstrate the synthesis and characterization of a high-density Co-based single-atom nanozyme anchored on activated MOF-derived porous carbon (Co-AcNC-3) via a cascade anchoring strategy for ultrasensitive, simultaneous electrochemical detection of catechol (CC) and hydroquinone (HQ). The Co-AcNC-3 displays a large specific surface area, high defectivity, and abundant oxygen-containing groups, with Co atoms being atomically dispersed throughout the carbon support via Co-N bonds. The Co-AcNC-3 biosensor exhibits superior electrochemical signals for CC and HQ, with linear ranges of 4.0 μM-300.0 μM. and detection limits of 0.072 μM and 0.034 μM, respectively. Moreover, the Co-AcNC-3 biosensor has shown excellent performance in accurately detecting CC and HQ in actual samples. Our findings highlight the potential of the proposed Co-AcNC-3 biosensor as a reliable and promising sensing platform for determining CC and HQ.

Recent Advances in Hierarchical Porous Engineering of MOFs and Their Derived Materials for Catalytic and Battery: Methods and Application

Hierarchical porous materials have attracted the attention of researchers due to their enormous specific surface area, maximized active site utilization efficiency, and unique structure and properties. In this context, metal-organic frameworks (MOFs) offer a unique mix of properties that make them particularly appealing as tunable porous substrates containing highly active sites. This review focuses on recent advances in the types and synthetic strategies of hierarchical porous MOFs and their derived materials. Furthermore, it highlights the relationship between the mass diffusion and transport of hierarchical porous structures and the pore size with examples and simulations, while identifying their potential and limitations. On this basis, how the synthesis conditions affect the structure and electrochemical properties of MOFs based hierarchical porous materials with different structures is discussed, highlighting the prospects and challenges for the synthetization, as well as further scientific research and practical applications. Finally, some insights into current research and future design ideas for advanced MOFs based hierarchical porous materials are presented.

Balanced Thermal Insulation, Flame-Retardant and Mechanical Properties of PU Foam Constructed via Cost-Effective EG/APP/SA Ternary Synergistic Modification

To address the challenge of balancing the mechanical, thermal insulation, and flame-retardant properties of building insulation materials, this study presented a facile approach to modify the rigid polyurethane foam composites (RPUFs) via commercial expandable graphite (EG), ammonium polyphosphate (APP), and silica aerogel (SA). The resulting EG/APP/SA/RPUFs exhibited low thermal conductivity close to neat RPUF. However, the compressive strength of the 6EG/2APP/SA/RPUF increased by 49% along with achieving a V-0 flame retardant rating. The residual weight at 700 °C increased from 19.2 wt.% to 30.9 wt.%. Results from cone calorimetry test (CCT) revealed a 9.2% reduction in total heat release (THR) and a 17.5% decrease in total smoke production (TSP). The synergistic flame-retardant mechanism of APP/EG made significant contribution to the excellent flame retardant properties of EG/APP/SA/RPUFs. The addition of SA played a vital role in reducing thermal conductivity and enhancing mechanical performance, effectively compensating for the shortcomings of APP/EG. The cost-effective EG/APP/SA system demonstrates a positive ternary synergistic effect in achieving a balance in RPUFs properties. This study provides a novel strategy aimed at developing affordable building wall insulation material with enhanced safety features.

Component-controlled synthesis of PdxSny nanocrystals on carbon nanotubes as advanced electrocatalysts for oxygen reduction reaction

Pd-based bimetallic or multimetallic nanocrystals are considered to be potential electrocatalysts for cathodic oxygen reduction reaction (ORR) in fuel cells. Although much advance has been made, the synthesis of component-controlled Pd-Sn alloy nanocrystals or corresponding nanohybrids is still challenging, and the electrocatalytic ORR properties are not fully explored. Herein, component-controlled synthesis of PdxSny nanocrystals (including Pd3Sn, Pd2Sn, Pd3Sn2, and PdSn) has been realized, which are in situ grown or deposited on pre-treated multi-walled carbon nanotubes (CNTs) to form well-coupled nanohybrids (NHs) by a facile one-pot non-hydrolytic system thermolysis method. In alkaline media, all the resultant PdxSny/CNTs NHs are effective at catalyzing ORR. Among them, the Pd3Sn/CNTs NHs exhibit the best catalytic activity with the half-wave potential of 0.85 V (vs. RHE), good cyclic stability, and excellent methanol-tolerant capability due to the suited Pd-Sn alloy component and its strong interaction or efficient electronic coupling with CNTs. This work is conducive to the advancement of Pd-based nanoalloy catalysts by combining component engineering and a hybridization strategy and promoting their application in clean energy devices.

One stone for four birds: A "chemical blowing" strategy to synthesis wood-derived carbon monoliths for high-mass loading capacitive energy storage in low temperature

Biomass-derived carbon materials are promising electrode materials for capacitive energy storage. Herein, inspired by the hierarchical structure of natural wood, carbon monoliths built up by interconnected porous carbon nanosheets with enriched vertical channels were obtained via zinc nitrate (Zn(NO3)2)-assisted synthesis and served as thick electrodes for capacitive energy storage. Zn(NO3)2 is proved to function as expansion agent, activator, dopant, and precursor of the template. The dense and micron-scale thickness walls of wood were expanded by Zn(NO3)2 into porous and interconnected nanosheets. The pore volume and specific surface area were increased by more than 430 %. The initial specific capacitance and rate performance of the optimized carbon monolith was approximately three times that of the pristine dense carbon framework. The assembled symmetric supercapacitor possessed a high initial specific capacitance of 4564 mF cm-2 (0-1.7 V) at -40 °C. Impressively, the robust device could be cycled more than 100,000 times with little capacitance attenuation. The assembled zinc-ion hybrid capacitor (0.2-2 V) delivered a large specific capacitance of 4500 mF cm-2 at -40 °C, approximately 74 % of its specific capacitance at 25 °C. Our research paves a new avenue to design thick carbon electrodes with high capacitive performance by multifunctional Zn(NO3)2 for low-temperature applications.

MOF-derived porous carbon nanozyme-based flexible electrochemical sensing system for in situ and real-time monitoring of H2O2 released from cells

A novel flexible electrochemical sensor based on porous carbon nanosheets (PCNSs) nanozyme has been constructed for in situ and real-time monitoring of H2O2 released by cells. The PCNSs are prepared with the integration of thermal transformation, thermal activation and sonochemical exfoliation by using zeolitic imidazolate frameworks as template. The PCNSs exhibit high electrical conductivity, electrochemical activity and peroxidase-like catalytic properties, which is beneficial to H2O2 assay. With the transfer printing method, the flexible electrochemical sensor is obtained, which has excellent performances for H2O2 electrochemical detecting with wide linear range from 1 μM to 20 mM and a low detection limit of 0.76 μM. Owing to the great biocompatibility, the flexible sensor guarantees the growth of living cells for 72 h and realizes in situ and real-time monitoring the release of H2O2 from HeLa cells. The strategy of porous nanozyme preparation and flexible sensor construction provided a promising way for in situ and real-time assay of small molecules in the cellular microenvironment.

NiM (Sb, Sn)/N-doped hollow carbon tube as high-rate and high-capacity anode for lithium-ion batteries

Alloy-type materials are regarded as prospective anode replacements for lithium-ion batteries (LIBs) owing to their attractive theoretical capacity. However, the drastic volume expansion leads to structural collapse and pulverization, resulting in rapid capacity decay during cycling. Here, a simple and scalable approach to prepare NiM (M: Sb, Sn)/nitrogen-doped hollow carbon tubes (NiMC) via template and substitution reactions is proposed. The nanosized NiM particles are uniformly anchored in the robust hollow N-doped carbon tubes via NiNC coordination bonds, which not only provides a buffer for volume expansion but also avoids agglomerating of the reactive material and ensures the integrity of the conductive network and structural framework during lithiation/delithiation. As a result, NiSbC and NiSnC exhibit high reversible capacities (1259 and 1342 mAh/g after 100 cycles at 0.1 A/g) and fascinating rate performance (627 and 721 mAh/g at 2 A/g), respectively, when employed as anodes of LIBs. The electrochemical kinetic analysis reveals that the dominant lithium storage behavior of NiMC electrodes varies from capacitive contribution to diffusion contribution during the cycling corresponding to the activation of the electrode exposing more NiM sites. Meanwhile, M (Sb, Sn) is gradually transformed into stable NiM during the de-lithium process, making the NiMC structure more stable and reversible in the electrochemical reaction. This work brings a novel thought to construct high-performance alloy-based anode materials.

Spindle Nanorods of CeO2 and NiS Heterointerface Coated by the NC Layer: A High-Performance Bifunctional Electrocatalyst for Water Splitting

Currently, nickel sulfides are widely employed in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), thanks to the narrow electronegativity difference of only 0.67 eV between nickel and sulfur. Among them, NiS stands out in terms of the OER performance; however, its HER performance and stability remain somewhat inadequate. The construction of heterogeneous interfaces can efficiently improve the HER performance and regulate the electronic structure of the NiS catalyst. CeO2 has been discovered to possess exceptional electronic modulation capabilities, which may lead to the effective enhancement of both HER and OER of the NiS catalyst. As a result, a nitrogen-doped carbon-coated CeO2-NiS heterogeneous interface catalyst (NC/NiS-CeO2) is designed as a bifunctional electrocatalyst for HER and OER with high performance. The NC/NiS-CeO2 catalyst demonstrates excellent HER (47 mV at 10 mA cm-2) and OER (92 mV at 10 mA cm-2) performances in a 1 M KOH alkaline solution. Characterization analysis reveals that the coupling of the heterostructure interface, which consists of CeO2 and NiS, significantly enhances electron conduction, the synergistic effect, and the electrocatalytic activity of the electrode. This study demonstrates that the HER and OER activity can be effectively improved by constructing a rational heterogeneous interface.

Analyzing Temperature Distribution Patterns on the Facing and Backside Surface: Investigating Combustion Performance of Flame-Retardant Particle Boards Using Aluminum Hypophosphite, Intumescent, and Magnesium Hydroxide Flame Retardants

Particle boards are manufactured through a hot pressing process using wood materials (natural polymer materials) and adhesive, which find common usage in indoor decorative finishing materials. Flame-retardant particleboard, crucial for fire safety in such applications, undergoes performance analysis that includes assessing temperature distribution across its facing surface and temperature increase on the backside surface during facade combustion, yielding critical insights into fire scenario development. In this study, a compact flame spread apparatus is utilized to examine the flame retardancy and combustion behavior of particle boards, with a specific emphasis on the application of cost-effective flame retardants, encompassing aluminum hypophosphite (ALHP), an intumescent flame retardant (IFR) comprising ammonium polyphosphate (APP), melamine (MEL), and Dipentaerythritol (DPE), alongside magnesium hydroxide (MDH), and their associated combustion characteristics. The D300°C values, representing the vertical distance from the ignition point (IP) to P300°C (the temperature point at 300 °C farthest from IP), are measured using a compact temperature distribution measurement platform. For MDH/PB, APP + MEL + DPE/PB, and ALHP/PB samples, the respective D300°C values of 145.79 mm, 117.81 mm, and 118.57 mm indicate reductions of 11.11%, 28.17%, and 27.71%, compared to the untreated sample's value of 164.02 mm. The particle boards treated with ALHP, IFR, and MDH demonstrated distinct flame-retardant mechanisms. MDH/PB relied on the thermal decomposition of MDH to produce MgO and H2O for flame retardancy, while APP + MEL + DPE/PB achieved flame retardancy through a cross-linked structure with char expansion, polyphosphate, and pyrophosphate during combustion. On the other hand, ALHP/PB attained flame retardancy by reacting with wood materials and adhesives, forming a stable condensed P-N-C structure. This study serves as a performance reference for the production of cost-effective flame-resistant particleboards and offers a practical method for assessing its fire-resistant properties when used as a decorative finishing material on facades in real fire situations.

Hierarchically Superstructured Anisotropic Carbon Particles by Multiscale Assembly Driven by Spinodal Decomposition

Hierarchical superstructures have novel shape-dependent properties, but well-defined anisotropic carbon superstructures with controllable size, shape, and building block dimensionality have rarely been accomplished thus far. Here, a hierarchical assembly technique is presented that uses spinodal decomposition (SD) to synthesize anisotropic oblate particles of mesoporous carbon superstructure (o-MCS) with nanorod arrays by integrating block-copolymer (BCP) self-assembly and polymer-polymer interface behaviors in binary blends. The interaction of major and minor phases in binary polymer blends leads to the formation of an anisotropic oblate particle, and the BCP-rich phase enables ordered packing and unidirectional alignment of carbon nanorods. Consequently, this approach enables precise control over particles' size, shape, and over the dimensionality of their components. Exploiting this functional superstructure, o-MCS are used as an anode material in potassium-ion batteries, and achieve a notable specific capacity of 156 mA h g-1 at a current density of 2 A g-1 , and long-term stability for 3000 cycles. This work presents a significant advancement in the field of hierarchical superstructures, providing a promising strategy for the design and synthesis of anisotropic carbon materials with controlled properties, offering promising applications in energy storage and beyond.

Metal ion assistant transformation strategy to synthesize catechol-based metal-organic frameworks from Ti3C2Tx precursors

Chemical transformation strategy is capable of fabricating nanomaterials with well-defined structures and fascinating performance via controllable crystallization kinetics in the phase transformation. V2CTx MXene has been used as precursors to fabricate vanadium porphyrin metal-organic frameworks (V-PMOFs) via the coordination of deprotonated carboxylic acid ligands. However, the rational and in-depth exploration of synthesis mechanism with the aim of enriching the variety of MXene (i.e., Ti3C2Tx) and organic ligands (i.e., catechol-based) to design new MOFs is rarely reported. Herein, we have first developed a metal ion assistant transformation strategy to synthesize three-dimensional catechol-based TiCu-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) MOFs with a non-interpenetrating SrSi2 (srs) framework using two-dimensional Ti3C2Tx as precursors. The unique synergetic transformation mechanism involves the electron transfer from Ti3C2Tx to electrostatically adsorbed Cu2+ ion for redox reaction, the subsequent Ti-C bond rupture for Ti4+ ion release, and the continuous chelation coordination between Ti4+/Cu2+ and HHTP. Ti3C2Tx precursors and auxiliary metal ion could be rationally substituted by V2CTx and Mn+ (e.g., Ni2+, Co2+, Mn2+, and Zn2+), respectively. This strategy lays the foundation for the design and synthesis of innovative and multifarious MOFs derived from MXene or other unconventional metal precursors.

High-Efficiency Electromagnetic Interference Shielding from Highly Aligned MXene Porous Composites via Controlled Directional Freezing

Lightweight porous composite materials (PCMs) with outstanding electromagnetic interference (EMI) shielding performances are ideal for aerospace, artificial intelligence, military, and other fields. Herein, a three-dimensional Ti3C2Tx MXene/sodium alginate (SA)/carbon nanotubes (CNTs) (MSC) PCMs was prepared by a controlled directional freezing process. This method constructs a directionally ordered porous structure, which can make the incident electromagnetic waves reflect and scattered several times in the PCMs. The introduction of CNTs into the MSC PCMs can form three-dimensional conductive networks with MXene, thus improving the conductivity and further improving the electromagnetic shielding performance. Furthermore, the SA with abundant hydrogen bonding can strengthen the interlayer interaction between MXene and CNTs. Profiting from the controlled directional freezing and highly aligned porous structure, the MSC PCMs with 75 wt % CNTs exhibit ultrahigh conductivity of 1630 S m-1, an ultrahigh EMI shielding effectiveness of 48.0 dB in X-band for electromagnetic waves incident perpendicular to the hole growth direction, and compressive strength of 72.3 kPa. The as-prepared MSC PCMs show excellent EMI shielding and mechanical properties and have significant applications in the preparation of an entirely novel type of EMI shielding materials with an absorption-based mechanism.

Ultrafast Subcellular Biolabeling and Bioresponsive Real-Time Monitoring for Targeting Cancer Theranostics

Cell heterogeneity poses a formidable challenge for tumor theranostics, requiring high-resolution strategies for intercellular bioanalysis between single cells. Nanoelectrode-based electrochemical analysis has attracted much attention due to its advantages of label-free characteristics, relatively low cost, and ultra-high resolution for single-cell analysis. Here, we have designed and developed a subcellular biolabeling and bioresponsive real-time monitoring strategy for precise bioimaging-guided cancer diagnosis and theranostics. Our observations revealed the apparent intracellular migration of biosynthetic Au nanoclusters (Au NCs) at different subcellular locations, i.e., from the mitochondria to the mitochondrion-free region in the cytoplasm, which may be helpful for controlling over the biosynthesis of Au NCs. Considering the precise biolabeling advantage of the intracellular biosynthetic Au NCs for biomedical imaging of cancers, it is important to realize the biosynthetic Au NC-enabled precise control in real-time theranostics of cancer cells. Therefore, this work raises the possibility to achieve subcellular monitoring of H2O2 for targeting cancer theranostics, thereby providing a new way to explore the underlying mechanism and imaging-guided tumor theranostics.

Flow-Through Electrochemical Membrane Reactor with a Self-Supported Carbon Membrane Electrode for Highly Efficient Synthesis of Hydrogen Peroxide

In situ electroreduction of O2 to H2O2 by using electrons as reagents is known as a green process, which is highly desirable for environmental remediation and chemical industries. However, the development of a cost-effective electrode with superior H2O2 synthesis rate and stability is challenging. A self-supported carbon membrane (CM) was prepared in this study from activated carbon and phenolic resin by carbonization under a H2 atmosphere. It was employed as the cathode to build a flow-through electrochemical membrane reactor (FT-ECMR) for electrosynthesis of H2O2. The results showed that the CM had a small pore size (34 nm), a high porosity (42.3%), and a high surface area (450.7 m2 g-1). In contrast to most of the state-of-the-art self-supported carbon electrode reported in the previous works, the FT-ECMR exhibited a high concentration of continuous and stable H2O2 electrosynthesis (1042 mg L-1) as well as a H2O2 synthesis rate of 5.21 mg h-1 cm-2. It had also demonstrated a high oxygen conversion (0.37%) and current efficiency (88%). The outstanding performance of the FT-ECMR for H2O2 synthesis was attributed to the enhanced mass transfer of the reactor, the existence of a relatively high surface area of CM, and the abundant disordered carbon structures (sp3-C, defects, and edges). In conclusion, our work highlighted using the FT-ECMR with the CM to synthesize H2O2 efficiently and cost-effectively.

A bimetallic Fe-Mg MOF with a dual role as an electrode in asymmetric supercapacitors and an efficient electrocatalyst for hydrogen evolution reaction (HER)

In this work, a novel bimetallic Fe-Mg/MOF was synthesized through a cost-effective and rapid hydrothermal process. The structure, morphology, and composition were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy. Further, the Brunauer-Emmett-Teller (BET) measurement showed a 324 m2 g-1 surface area for Fe-Mg/MOF. The Fe-Mg/MOF achieved 1825 C g-1 capacity at 1.2 A g-1 current density, which is higher than simple Fe-MOF (1144 C g-1) and Mg-MOF (1401 C g-1). To assess the long-term stability of the asymmetric device, the bimetallic MOF supercapattery underwent 1000 charge/discharge cycles and retained 85% of its initial capacity. The energy and power densities were calculated to be 57 W h kg-1 and 2393 W kg-1, respectively. Additionally, Fe-Mg/MOF showed superior electrocatalytic performance in hydrogen evolution reaction (HER) by demonstrating a smaller Tafel slope of 51.43 mV dec-1. Our research lays the foundation for enhancing the efficiency of energy storage technologies, paving the way for more sustainable and robust energy solutions.

Lithium Azides Induced SnS Quantum Dots for Ultra-Fast and Long-Term Sodium Storage

Tin sulfide (SnS) is an attractive anode for sodium ion batteries (NIBs) because of its high theoretical capacity, while it seriously suffers from the inherently poor conductivity and huge volume variation during the cycling process, leading to inferior lifespan. To intrinsically maximize the sodium storage of SnS, herein, lithium azides (LiN3 )-induced SnS quantum dots (QDs) are first reported using a simple electrospinning strategy, where SnS QDs are uniformly distributed in the carbon fibers. Taking the advantage of LiN3 , which can effectively prevent the growth of crystal nuclei during the thermal treatment, the well-dispersed SnS QDs performs superior Na+ transfer kinetics and pseudocapacitive when used as an anode material for NIBs. The 3D SnS quantum dots embedded uniformly in N-doped nanofibers (SnS QDs@NCF) electrodes display superior long cycling life-span (484.6 mAh g-1 after 5800 cycles at 2 A g-1 and 430.9 mAh g-1 after 7880 cycles at 10 A g-1 ), as well as excellent rate capability (422.3 mAh g-1 at 20 A g-1 ). This fabrication of transition metal sulfides QDs composites provide a feasible strategy to develop NIBs with long life-span and superior rate capability to pave its practical implementation.

Straightforward Strategy Toward In Situ Water-Phase Exfoliation and Improved Interfacial Adhesion to Fabricate High-Performance Polypropylene/Graphene Nanocomposites

Graphene is a potential candidate for achieving high-performance and multifunctional polypropylene (PP) composites. However, the complex manufacturing process and low dispersibility of graphene, as well as poor interfacial adhesion between graphene and polypropylene chains, stifle progress on large-scale production and applications of graphene/polypropylene composites. Here, we develop a strategy of maleic anhydride grafted polypropylene (MAPP) latex-assisted graphene exfoliation and melt blending to address the key challenges facing in industrial production. The surface property of the graphitic precursor is well-designed to achieve a high graphene exfoliation yield of ∼100% and induce abundant hydrogen bonding between the obtained mild-oxidized graphene (MOG) sheets and MAPP chains. Therefore, the MAPP-modified MOG can homogeneously disperse in the PP matrix and exhibits an excellent interfacial compatibility with the polymer. The addition of 5 wt % MOG results in simultaneous increase in the initial decomposition temperature, crystallization temperature, tensile strength, and Young's modulus by 43.2, 11.4 °C, 21.5, and 50.7%, respectively, and the electrical conductivity increases to 0.02 S·m-1. This work illustrates a practical solution to low-cost, eco-friendly, and feasible industrial production of graphene/PP composites through synchronous exfoliation and interfacial modification of graphene.

Defect-Engineered Mesoporous Undoped Carbon Nanoribbons for Benchmark Oxygen Reduction Reaction

For large-scale fuel cell applications, it is significant to replace expensive Pt-based oxygen reduction reaction (ORR) electrocatalysts with nonprecious metal- or metal-free carbon-based catalysts with high activity. However, it is still challenging to deeply understand the role of intrinsic defects and the origin of ORR activity in pure nanocarbon. Therefore, a novel self-assembly and a pyrolysis strategy to fabricate defect-rich mesoporous carbon nanoribbons are presented. Due to the effective regulation of nanoarchitecture, a vast number of defective catalytic sites (edge defects and holes) are exposed, which thereby enhances the electron transfer kinetics and catalytic activity. Such undoped nanoribbons display a large half-wave potential of 0.837 V, excellent long-term stability, and exceptional methanol tolerance, surpassing the most undoped ORR catalysts and the commercial Pt/C (20 wt.%) catalyst. Structural characterizations and density functional theory (DFT) calculations confirm that the zigzag edge defects and the armchair pentagon at the hole defect are responsible for outstanding ORR performance.

Graphene/Heterojunction Composite Prepared by Carbon Thermal Reduction as a Sulfur Host for Lithium-Sulfur Batteries

An interlayer nanocomposite (CC@rGO) consisting of a graphene heterojunction with CoO and Co₉S₈ was prepared using a simple and low-cost hydrothermal calcination method, which was tested as a cathode sulfur carrier for lithium-sulfur batteries. The CC@rGO composite comprises a spherical heterostructure uniformly distributed between graphene sheet layers, preventing stacking the graphene sheet layer. After the introduction of cobalt heterojunction on a graphene substrate, the Co element content increases the reactive sites of the composite and improves its electrochemical properties to some extent. The composite exhibited good cycling performance with an initial discharge capacity of 847.51 mAh/g at 0.5 C and a capacity decay rate of 0.0448% after 500 cycles, which also kept 452.91 mAh/g at 1 C and in the rate test from 3 C back to 0.1 C maintained 993.27 mAh/g. This article provides insight into the design of cathode materials for lithium-sulfur batteries.

Recent strategies for constructing hierarchical multicomponent nanoparticles/metal-organic framework hybrids and their applications

Hybrid nanoparticles with unique tailored morphologies and compositions can be utilized for numerous applications owing to their combination of inherent properties as well as the structural and supportive functions of each component. Controlled encapsulation of nanoparticles within nanospaces (NPNSs) of metal-organic frameworks (MOFs) (denoted as NPNS@MOF) can generate a large number of hybrid nanomaterials, facilitating superior activity in targeted applications. In this review, recent strategies for the fabrication of NPNS@MOFs with a hierarchical architecture, tailorability, unique intrinsic properties, and superior catalytic performance are summarized. In addition, the latest and most important examples in this sector are emphasized since they are more conducive to the practical applicability of NPNS@MOF nanohybrids.

Strong interface coupling boosting hierarchical bismuth embedded carbon hybrid for high-performance capacitive deionization

Capacitive deionization (CDI) is regarded as a promising desalination technology owing to its low cost and environmental friendliness. However, the lack of high-performance electrode materials remains a challenge in CDI. Herein, the hierarchical bismuth-embedded carbon (Bi@C) hybrid with strong interface coupling was prepared through facile solvothermal and annealing strategy. The hierarchical structure with strong interface coupling between the bismuth and carbon matrix afforded abundant active sites for chloridion (Cl^-) capture, improved electrons/ions transfer and the stability of the Bi@C hybrid. As a result of these advantages, the Bi@C hybrid showed a high salt adsorption capacity (75.3 mg/g under 1.2 V), salt adsorption rate and good stability, making it a promising electrode material for CDI. Furthermore, the desalination mechanism of the Bi@C hybrid was elucidated through various characterizations. Therefore, this work provides valuable insights for the design of high-performance bismuth-based electrode materials for CDI.

Hydrogen bonds and space restriction promoting long-lived room-temperature phosphorescence and its application for white light-emitting diodes

Achieving the long-lived and strong room-temperature phosphorescence (RTP) is challengeable but desirable, especially for the enhanced phosphorescence and metal-free nanomaterials. Herein, we initially synthesized the green-fluorescence carbon dots (pm-CDs), and further obtained the composite of pm-CDs@DCDA with a long RTP lifetime of 1.01 s through embedding pm-CDs in dicyandiamide (DCDA). And the bright and long-lived afterglow of pm-CDs@DCDA with 365 nm of UV light excitation was observed by the naked eyes for more than 17 s either emerging as the dry solid or in water. Importantly, the phosphorescence intensity and lifetime of pm-CDs@DCDA were remarkably promoted owing to the intermolecular hydrogen bonds and the rigid environment, hence facilitating the intersystem crossing (ISC) process and restricting the non-radiative transition of triplet excitons. Taking advantage of the superior solid-state luminescence of pm-CDs@DCDA, we further innovatively prepared the white light-emitting diodes (WLEDs) with the tunable color temperatures by regulating the mass of pm-CDs@DCDA coated on the chips. This proposed study originally employed DCDA as a matrix to separate and immobilize pm-CDs, which built up a new avenue to improve the RTP property and offered a promising application in WLEDs.

Understanding and Optimizing Capacitance Performance in Reduced Graphene-Oxide Based Supercapacitors

Reduced graphene-oxide (RGO)-based electrodes in supercapacitors deliver high energy/power capacities compared to typical nanoporous carbon materials. However, extensive critical analysis of literature reveals enormous discrepancies (up to 250 F g^-1 ) in the reported capacitance (variation of 100-350 F g^-1 ) of RGO materials synthesized under seemingly similar methods, inhibiting an understanding of capacitance variation. Here, the key factors that control the capacitance performance of RGO electrodes are demonstrated by analyzing and optimizing various types of commonly applied electrode fabrication methods. Beyond usual data acquisition parameters and oxidation/reduction properties of RGO, a substantial difference of more than 100% in capacitance values (with change from 190 ± 20 to 340 ± 10 F g^-1 ) is found depending on the electrode preparation method. For this demonstration, ≈40 RGO-based electrodes are fabricated from numerous distinctly different RGO materials via typically applied methods of solution (aqueous and organic) casting and compressed powders. The influence of data acquisition conditions and capacitance estimation practices are also discussed. Furthermore, by optimizing electrode processing method, a direct surface area governed capacitance relationship for RGO structures is revealed.

Recent Advances in Porous Carbon Materials as Electrodes for Supercapacitors

Porous carbon materials have demonstrated exceptional performance in various energy and environment-related applications. Recently, research on supercapacitors has been steadily increasing, and porous carbon materials have emerged as the most significant electrode material for supercapacitors. Nonetheless, the high cost and potential for environmental pollution associated with the preparation process of porous carbon materials remain significant issues. This paper presents an overview of common methods for preparing porous carbon materials, including the carbon-activation method, hard-templating method, soft-templating method, sacrificial-templating method, and self-templating method. Additionally, we also review several emerging methods for the preparation of porous carbon materials, such as copolymer pyrolysis, carbohydrate self-activation, and laser scribing. We then categorise porous carbons based on their pore sizes and the presence or absence of heteroatom doping. Finally, we provide an overview of recent applications of porous carbon materials as electrodes for supercapacitors.

Effect of modulator ligands on the growth of Co2(dobdc) nanorods

Control over the size, shape, uniformity, and external surface chemistry of metal-organic framework nanocrystals is important for a wide range of applications. Here, we investigate how monotopic modulators that mimic the coordination mode of native bridging ligands affect the growth of anisotropic Co2(dobdc) (dobdc4- = 2,5-dihydroxy-1,4-benzenedicarboxylic acid) nanorods. Through a combination of transmission electron microscopy (TEM) and nuclear magnetic resonance spectroscopy (NMR) studies, nanorod diameter was found to be strongly correlated to the acidity of the modulator and to the degree of modulator incorporation into the nanorod structure. Notably, highly acidic modulators allowed for the preparation of sub-10 nm nanorods, a previously elusive size regime for the M2(dobdc) family. More broadly, this study provides new insights into the mechanism of modulated growth of metal-organic framework nanoparticles.

Nanoantibiotic effect of carbon-based nanocomposites: epicentric on graphene, carbon nanotubes and fullerene composites: a review

Carbon in many different forms especially, Graphene, Carbon nanotubes (CNTs), and Fullerene is emerging as an important material in the areas of the biomedical field for various applications. This review comprehensively describes the nano antibiotic effect of carbon-based nanocomposites: epicenter on graphene, carbon nanotubes, and fullerene Composites. It summarises the studies conducted to evaluate their antimicrobial applications as they can disrupt the cell membrane of bacteria resulting in cell death. The initial section gives a glimpse of both "Gram"-positive and negative bacteria, which have been affected by Graphene, CNTs, and Fullerene-based nanocomposites. These bacteria include Staphylococcus Aureus, Bacillus Thuringiensis, Enterococcus faecalis, Enterococcus faecium, Bacillus subtilis, Escherichia coli, Klebseilla pneumoniae, Pseudomonas aeroginosa, Pseudomonas syringae , Shigella flexneri,Candida Albicans, Mucor. Another section is dedicated to the insight of Graphene, and its types such as Graphene Oxide (GO), Reduced graphene oxide (rGO), Graphene Nanoplatelets (GNPs), Graphene Nanoribbons (GNRs), and Graphene Quantum Dots (GQDs). Insight into CNT, including both the types SWCNT and MWCNT, studied, followed by understanding fullerene is also reported. Another section is dedicated to the antibacterial mechanism of Graphene, CNT, and Fullerene-based nanocomposites. Further, an additional section is dedicated to a comprehensive review of the antibacterial characteristics of Graphene, CNT, and nanocomposites based on fullerene. Future perspectives and recommendations have also been highlighted in the last section.

Boosting Li-O2 Battery Performance via Coupling of P-N Site-Rich N, P Co-Doped Graphene-Like Carbon Nanosheets with Nano-CePO4

Development of efficient and robust cathode catalysts is critical for the commercialization of Li-O₂ batteries (LOBs). Herein, a well-designed CePO₄ @N-P-CNSs cathode catalyst for LOBs via coupling P-N site-rich N, P co-doped graphene-like carbon nanosheets (N-P-CNSs) with nano-CePO₄ via a novel "in situ derivation" coupling strategy by in situ transforming the P atoms of P-C sites in N-P-CNSs to CePO₄ is reported. The CePO₄ @N-P-CNSs exhibit superior bifunctional ORR/OER activity relative to commercial Pt/C-RuO₂ with an overall overpotential of 0.64 V (vs RHE). Moreover, the LOB with CePO₄ @N-P-CNSs as the cathode catalyst delivers a low charge overpotential of 0.67 V (vs Li/Li⁺ ), high discharge capacity of 29774 mAh g^-1 at 100 mA g^-1 and long cycling stability of 415 cycles, respectively. The remarkably enhanced LOB performance is attributable to the in situ derived CePO₄ nanoparticles and the P-N sites in N-P-CNSs, which facilitate increased bifunctional ORR/OER activity, promote the rapid and effective decomposition of Li₂ O₂ and inhibit the formation of Li₂ CO₃ . This work may provide new inspiration for designing efficient, durable, and cost-effective cathode catalysts for LOBs.

Self-supporting electrocatalyst constructed from in-situ transformation of Co(OH)2 to metal-organic framework to Co/CoP/NC nanosheets for high-current-density water splitting

Transition metal phosphide (TMP) emerges as a promising electrocatalyst for overall water splitting (OWS). However, conventional TMP materials require exogenous metal ions to participate in coordination reactions, which usually suffer from active site blocking, pronounced intrinsic impedance, and inevitable catalyst shedding at high current density. Herein, a novel in-situ construction strategy has been developed to grow N-doped carbon (NC) enwrapped Co/CoP nanosheets directly onto Co foam (abbreviated as CoF) through a three-step transformation of Co to Co(OH)₂ to Co-Metal-Organic Framework (Co-MOF) to Co/CoP/NC. In the entire preparation process, Co metal is only provided by the CoF substrate without external metal sources. Such in-situ construction yields tight contact at the interface of the heterogeneous catalyst, leading to much-reduced impedance and boundary vacancy, while the porous nitrogen-doped carbon backbone further endows the catalyst with the exposure of massive active sites, promotes mass transfer, and possesses high electrical conductivity. The Co/CoP/NC/CoF requires overpotentials of only 64 mV/263 mV@10 mA cm^-2 and 414 mV/481 mV@400 mA cm^-2 for both HER/OER in 1.0 M KOH, respectively. Remarkably, it reveals excellent OWS catalytic activity with a cell voltage of 1.56 V@10 mA cm^-2 and 1.88 V@200 mA cm^-2. This strategy of in-situ interface engineering transformation provides new ideas for direct device processing and construction of highly-efficient transition-metal-based OWS electrode materials.

Two-Dimensional Metal Organic Framework derived Nitrogen-doped Graphene-like Carbon Nanomesh toward Efficient Electromagnetic Wave Absorption

Functional two-dimensional (2D) graphene-like carbon has the potential to be a good electromagnetic wave absorbing material due to its good electronic properties, but the preparation of 2D carbon via metal-organic frameworks (MOFs) derivation method is still a bottleneck. Herein, we fabricated ultrathin nitrogen-doped graphene-like carbon nanomesh (N-GN) via thermal exfoliation of 2D MOF (Zn-ZIF-L) directly. The species of the chloride salt that exfoliated Zn-ZIF-L have an effect on the nitrogen content, graphitization degree, pore size and specific surface area of N-GN. The Zn-ZIF-L derived N-GN exfoliated by KCl and LiCl simultaneously has the optimum reflection loss of -54 dB only with the thickness of 2.1 mm and the filler loading of 3 wt%. The excellent electromagnetic wave absorbing property is attributed to its favorable structure, micro-meso-macropores, N heteroatoms, abundant heterogeneous graphene-like carbon nanomesh interfaces and defects. Our simple and low-cost preparation process facilitates the large-scale production and application for electromagnetic wave absorbing material of functionalized graphene-like carbon.

Porous Organic Cages

Porous organic cages (POCs) are a relatively new class of low-density crystalline materials that have emerged as a versatile platform for investigating molecular recognition, gas storage and separation, and proton conduction, with potential applications in the fields of porous liquids, highly permeable membranes, heterogeneous catalysis, and microreactors. In common with highly extended porous structures, such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and porous organic polymers (POPs), POCs possess all of the advantages of highly specific surface areas, porosities, open pore channels, and tunable structures. In addition, they have discrete molecular structures and exhibit good to excellent solubilities in common solvents, enabling their solution dispersibility and processability─properties that are not readily available in the case of the well-established, insoluble, extended porous frameworks. Here, we present a critical review summarizing in detail recent progress and breakthroughs─especially during the past five years─of all the POCs while taking a close look at their strategic design, precise synthesis, including both irreversible bond-forming chemistry and dynamic covalent chemistry, advanced characterization, and diverse applications. We highlight representative POC examples in an attempt to gain some understanding of their structure-function relationships. We also discuss future challenges and opportunities in the design, synthesis, characterization, and application of POCs. We anticipate that this review will be useful to researchers working in this field when it comes to designing and developing new POCs with desired functions.

Adsorptivity and kinetics for low concentration of gaseous formaldehyde on bamboo-based activated carbon loaded with ammonium acetate particles

The highly promising formaldehyde (HCHO)-removing materials are essential for eliminating interior pollution to safeguard the public's health with increasing indoor HCHO contamination situations being recorded on a global scale. In the paper, bamboo charcoal (BC) was activated with boric acid to prepare bamboo-based activated carbon (BAC), and then impregnated with ammonium acetate solution to successfully develop porous adsorbent with ammonium acetate particles (N/BAC), which was applied to remove low concentration of HCHO at room temperature. The adsorption performance for HCHO was systematically investigated while the surface chemical properties and microstructure of the as-prepared adsorbents were described and analyzed. The specific surface area, total pore volume and microporous volume of N/BAC sample were 240.09 m²/g, 0.27 cm³/g and 0.12 cm³/g, which increased by 42.40 m²/g, 0.15 cm³/g and 0.03 cm³/g compared with BAC sample, respectively. The specific surface area and the microporous volume, as well as the content of oxygen- and nitrogen-containing functional groups of N/BAC sample were augmented by contrast with other samples, and numerous ammonium acetate particles were present on the surface. Precisely because of this, the N/BAC sample exhibited a high removal rate of 98.89%, which was 18.38% greater than that of BAC sample. A superior correlation coefficient (0.9999) from the experimental values of the kinetics and the fitted values of the pseudo-second-order kinetic model demonstrated that the adsorption process of HCHO on N/BAC sample was physical-chemical combined adsorption. The adsorption of HCHO on N/BAC sample was investigated under different humidity, and the results showed that the adsorbent yet had excellent adsorption capacity (87.93%) under RH 75%. Moreover, the N/BAC sample was renewable, and the removal rate still reached 82.81% after five cycles of regeneration. Therefore, the as-prepared adsorbent is an effective, economical and sustainable material, and could be used to remove HCHO from real contaminated indoor air.