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

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.

Defect-Enriched Graphene Nanoribbons Tune the Adsorption Behavior of the Mediator to Boost the Lactate/Oxygen Biofuel Cell

Owing to the high efficiency and specificity in moderate conditions, enzymatic biofuel cells (EBFCs) have gained significant interest as a promising energy source for wearable devices. However, the instability of the bioelectrode and the lack of efficient electrical communication between the enzymes and electrodes are the main obstacles. Herein, defect-enriched 3D graphene nanoribbons (GNRs) frameworks are fabricated by unzipping multiwall carbon nanotubes, followed by thermal annealing. It is found that defective carbon shows stronger adsorption energy towards the polar mediators than the pristine carbon, which is beneficial to improving the stability of the bioelectrodes. Consequently, the EBFCs equipped with the GNRs exhibit a significantly enhanced bioelectrocatalytic performance and operational stability, delivering an open-circuit voltage and power density of 0.62 V, 70.7 μW/cm², and 0.58 V, 18.6 μW/cm² in phosphate buffer solution and artificial tear, respectively, which represent the high levels among the reported literature. This work provides a design principle according to which defective carbon materials could be more suitable for the immobilization of biocatalytic components in the application of EBFCs.

Adsorption of chloramphenicol from water using Carex meyeriana Kunth-derived hierarchical porous carbon with open channel arrays

A carbon material with both open macrochannel arrays and abundant micro/mesopores was prepared, characterized, and applied for removing chloramphenicol (CAP) from water. In the preparation process, Carex meyeriana Kunth (CM) with natural channel arrays was used as the precursor for producing the biochar, and NaOH was used for removing silicon and formatting micro- and mesopores of the porous carbon. The product (PCCM) exhibited the highest specific surface area (2700.24 m² g^-1) among the reported CM-derived porous carbons. The adsorption performances of PCCM were evaluated through batch adsorption experiments. The maximum adsorption capacity of PCCM toward CAP was 1659.43 mg g^-1. The adsorption mechanism was investigated with the aid of theoretical calculations. Moreover, PCCM exhibited better performance than other porous carbon adsorbents in fixed-bed experiments, which may be due to its structural advantages.

Squaraine dye/Ti3C2Tx MXene organic-inorganic hybrids for photocatalytic hydrogen evolution

MXenes, a new family of 2D nanostructured materials, have been widely studied in the field of artificial photosynthesis due to their outstanding physicochemical properties. In this work, a series of 2,4-bis[4-(N,N-dibutylamino)phenyl] squaraine (SQ) derivatives with different number of hydroxyl groups were hybridized with Ti₃C₂T_x MXene nanosheets, and the organic-inorganic hybrid photocatalysts were applied for water-splitting hydrogen evolution. The mass ratios of SQ@Ti₃C₂T_x were optimized to 4 wt% for each SQ, and the best hydrogen evolution reaction (HER) rate of 28.6 μmol h^-1 g^-1 was achieved by SQ-3 with four OH groups. The photocatalytic ability of the hybrid comes from the outstanding light harvesting of SQ dye, sufficient active sites of Ti₃C₂T_x, and efficient separation and transfer of the photogenerated charges via heterojunction between SQ aggregates and Ti₃C₂T_x. This work firstly demonstrates an example of SQ sensitizer combined with MXene for hydrogen generation, which provides a new insight to further explore the MXene-based hybrid nanomaterials for water splitting hydrogen evolution.

2D MOF derived cobalt and nitrogen-doped ultrathin oxygen-rich carbon nanosheets for efficient Fenton-like catalysis: Tuning effect of oxygen functional groups in close vicinity to Co-N sites

Developing highly efficient catalysts for peroxymonosulfate (PMS) activation is an important issue in advanced oxidation processes (AOPs) technology. In this work, cobalt and nitrogen-doped ultrathin oxygen-rich carbon nanosheets derived from 2D metal-organic framework (MOF) were successfully fabricated. The as-prepared catalyst can effectively degrade tetracycline (TC) with a high reaction constant (0.088 min^-1). Quenching test, electron paramagnetic resonance (EPR) technology, and the electrochemical test indicate that the radical pathway plays a minor role in the degradation process, the ¹O₂ based nonradical pathway dominates the reaction. Experimental and density functional theory (DFT) studies revealed that the Co-N sites on the carbon structure serve as the dominant active sites, and the oxygen functional groups in close vicinity to Co-N sites can dramatically influence local electronic structure and its interaction with PMS molecule, a high correlation between the reaction constant and hydroxy groups content could be due to the Co-N sites close to hydroxyl groups has a moderate PMS adsorption energy. This work provides new insight into the design of highly efficient Fenton-like catalysts.

Controllable Preparation of Eucommia Wood-Derived Mesoporous Activated Carbon as Electrode Materials for Supercapacitors

Activated carbons (ACs) for supercapacitors were synthesized from Eucommia ulmoides Oliver (EUO) wood by H₃PO₄ with systemic activation processes. The target structure of ACs could be prepared by adjusting the technological parameters. As the H₃PO₄ concentration was 25%, the mass ratio of feedstocks to activator was 1:4, the activation time was 6 h, and the activation temperature was 400 °C, the obtained AC revealed a high specific surface area (2033.87 m²·g^-1) and well-developed mesoporous (the rate of mesoporous was 96.4%) with the best economic feasibility. Besides, it possessed excellent electrochemical performance: the maximum specific capacitance reached up to 252 F·g^-1, the charging and discharging period was 3098.2 s at 0.2 A·g^-1, and the retention rate of specific capacitance reached 92.3% after 10,000 cycles. This low temperature and convenience technology provide a valuable reference for synthesizing the EUO-based ACs, making high-value utilization on the EUO branches, and owning a broad application prospect in supercapacitors.

Photonic double-network hydrogel dressings for antibacterial phototherapy and inflammation regulation in the general management of cutaneous regeneration

The treatment of festering pathogenic bacteria-induced skin wounds with increased inflammation is an ongoing challenge. The traditional antibacterial photothermal therapy always results in localized hyperthermia (over 50 °C), which inevitably delays tissue recovery. To address this serious issue, we devise a novel photonic hydrogel by integrating urchin-like Bi₂S₃ nano-heterojunctions (nano-HJs) into double-network hydrogels for infected skin regeneration. The synergy of NIR-triggered heat and ROS enables the hydrogels to achieve a rapid germicidal efficacy against bacteria within 15 min at mild temperature (below 50 °C). In vitro cell analysis results revealed that the photonic hydrogels exhibit superior cytocompatibility even after NIR illumination. More importantly, an in vivo study demonstrated that the photonic hydrogel dressings have a robust ability of accelerating contagious full-thickness wound regeneration through debriding abscesses, eliminating pathogens, improving collagen deposition, promoting angiogenesis, and adjusting the inflammation state. This photonic hydrogel system provides a general management strategy for the remedy of infectious wounds, where the incorporation of nano-HJs endows the hydrogels with the photodisinfection ability; in addition, the multifunctional hydrogels alleviate the damage from overwhelming heat towards surrounding tissues during phototherapy and steer the inflammation during the process of tissue regeneration. Accordingly, this work highlights the promising application of the photonic hydrogels in conquering refractory pathogen-invaded infection.

Optical Force-Induced Nanowire Cut

One-dimensional nanometer scale-sized materials, such as nanowires, nanotubes, etc., have gradually become new types of structural components, which can be integrated into micro/nano-opto-electromechanical systems. In this paper, optical forces were applied to cut nanowires precisely, which were broken with arbitrary length ratios. The optical force exerted by the optical tweezers proved to be the cause of the fracture of the high-aspect ratio nanowires, and the fracture mechanism of the nanowires was developed. Nanowires of different semiconductor materials were cut with optical tweezers in the experiments. The precise cut with optical tweezers can provide nanowires of appropriate lengths for the construction of nanowire-based structures, which have potential applications for micromachining and microfabrication of micro-electro-mechanical system or semiconductor devices.

General Synthesis of MOF Nanotubes via Hydrogen-Bonded Organic Frameworks toward Efficient Hydrogen Evolution Electrocatalysts

The application scope of metal-organic frameworks (MOFs) can be extended by rationally designing the architecture and components of MOFs, which can be achieved via a metal-containing solid templated strategy. However, this strategy suffers from low efficiency and provides only one specific MOF from one template. Herein, we present a versatile templated strategy in which organic ligands are weaved into hydrogen-bonded organic frameworks (HOFs) for the controllable and scalable synthesis of MOF nanotubes. HOF nanowires assembled from benzene-1,3,5-tricarboxylic acid and melamine via a simple sonochemical approach serve as both the template and precursor to produce MOF nanotubes with varied metal compositions. Hybrid nanotubes containing nanometal crystals and N-doped graphene prepared through a carbonization process show that the optimized NiRuIr alloy@NG nanotube exhibits excellent electrocatalytic HER activity and durability in alkaline media, outperforming most reported catalysts. The strategy proposed here demonstrates a pioneering study of combination of HOF and MOF, which shows great potential in the design of other nanosized MOFs with various architectures and compositions for potential applications.

Conductive Metal-Organic Frameworks for Supercapacitors

As a class of porous materials with crystal lattices, metal-organic frameworks (MOFs), featuring outstanding specific surface area, tunable functionality, and versatile structures, have attracted huge attention in the past two decades. Since the first conductive MOF is successfully synthesized in 2009, considerable progress has been achieved for the development of conductive MOFs, allowing their use in diverse applications for electrochemical energy storage. Among those applications, supercapacitors have received great interest because of their high power density, fast charging ability, and excellent cycling stability. Here, the efforts hitherto devoted to the synthesis and design of conductive MOFs and their auspicious capacitive performance are summarized. Using conductive MOFs as a unique platform medium, the electronic and molecular aspects of the energy storage mechanism in supercapacitors with MOF electrodes are discussed, highlighting the advantages and limitations to inspire new ideas for the development of conductive MOFs for supercapacitors.

2D-Materials-Based Wearable Biosensor Systems

As an evolutionary success in life science, wearable biosensor systems, which can monitor human health information and quantify vital signs in real time, have been actively studied. Research in wearable biosensor systems is mainly focused on the design of sensors with various flexible materials. Among them, 2D materials with excellent mechanical, optical, and electrical properties provide the expected characteristics to address the challenges of developing microminiaturized wearable biosensor systems. This review summarizes the recent research progresses in 2D-materials-based wearable biosensors including e-skin, contact lens sensors, and others. Then, we highlight the challenges of flexible power supply technologies for smart systems. The latest advances in biosensor systems involving wearable wristbands, diabetic patches, and smart contact lenses are also discussed. This review will enable a better understanding of the design principle of 2D biosensors, offering insights into innovative technologies for future biosensor systems toward their practical applications.

Application of Graphene Nanoplatelets in Supercapacitor Devices: A Review of Recent Developments

As worldwide energy consumption continues to increase, so too does the demand for improved energy storage technologies. Supercapacitors are energy storage devices that are receiving considerable interest due to their appealing features such as high power densities and much longer cycle lives than batteries. As such, supercapacitors fill the gaps between conventional capacitors and batteries, which are characterised by high power density and high energy density, respectively. Carbon nanomaterials, such as graphene nanoplatelets, are being widely explored as supercapacitor electrode materials due to their high surface area, low toxicity, and ability to tune properties for the desired application. In this review, we first briefly introduce the theoretical background and basic working principles of supercapacitors and then discuss the effects of electrode material selection and structure of carbon nanomaterials on the performances of supercapacitors. Finally, we highlight the recent advances of graphene nanoplatelets and how chemical functionalisation can affect and improve their supercapacitor performance.

An efficient NiCu@C/Al2O3 catalyst for selective hydrogenation of acetylene

The development of non-noble metal catalysts for selective hydrogenation still remains a challenge. Herein, NiCu@carbon core-shell nanoparticles supported on Al₂O₃ (NiCu@C/Al₂O₃) were prepared, which showed enhanced catalytic performance of acetylene-selective hydrogenation in comparison with NiCu/Al₂O₃ without carbon encapsulation. In detail, NiCu@C/Al₂O₃ displayed high ethylene selectivity (>86%) even at an acetylene conversion of 100% and excellent stability (>90 h). Thus, NiCu@C/Al₂O₃ exhibited great potential as an alternative to Pd-based catalysts for acetylene-selective hydrogenation.

Metal-Organic Framework Materials for Electrochemical Supercapacitors

Exploring new materials with high stability and capacity is full of challenges in sustainable energy conversion and storage systems. Metal-organic frameworks (MOFs), as a new type of porous material, show the advantages of large specific surface area, high porosity, low density, and adjustable pore size, exhibiting a broad application prospect in the field of electrocatalytic reactions, batteries, particularly in the field of supercapacitors. This comprehensive review outlines the recent progress in synthetic methods and electrochemical performances of MOF materials, as well as their applications in supercapacitors. Additionally, the superiorities of MOFs-related materials are highlighted, while major challenges or opportunities for future research on them for electrochemical supercapacitors have been discussed and displayed, along with extensive experimental experiences.

A Hexagonal Nut-Like Metal-Organic Framework and Its Conformal Transformation

Hollow structured metal-organic frameworks (MOFs) and their derivatives are desired in catalysis, energy storage, etc. However, fabrication of novel hollow MOFs and revelation of their formation mechanisms remain challenging. Herein, open hollow 2D MOFs in the form of hexagonal nut are prepared through self-template method, which can be readily scaled up at gram scale in a one-pot preparation. The evolution from the initial superstructure to the final stable MOFs is tracked by wide-angle X-ray scattering, transforming from solid hexagon to open hollow hexagon. More importantly, this protocol can be extended to synthesizing a series of open hollow structured MOFs with sizes ranging from ≈120 to ≈1200 nm. Further, open hollow structured cobalt/N-doped porous carbon composites are realized through conformal transformation of the as-prepared MOFs, which demonstrates promising applications in sustainable energy conversion technologies. This study sheds light on the kinetically controlled synthesis of novel 2D MOFs for their extended utilizations.

Two-step ball milling-assisted synthesis of N-doped biochar loaded with ferrous sulfide for enhanced adsorptive removal of Cr(Ⅵ) and tetracycline from water

Nitrogen-doped biochar loaded with FeS (FeS@NBC_BM) was synthesized by two-step ball milling processes. Characterization results revealed that N-doping process successfully introduced pyridinic, pyrrolic, and graphitic N structures, and FeS was subsequently embedded in N-doped biochar (NBC_BM). The resultant FeS@NBC_BM presented predominant adsorption capacity for Cr(VI) (194.69 mg/g) and tetracycline (TC, 371.29 mg/g) compared with BC (27.28 and 37.89 mg/g) and NBC_BM (71.26 and 81.26 mg/g). In addition, the Cr(VI)/TC elimination process by FeS@NBC_BM was basically stable with multiple co-existing ions with slight decrease on adsorption performance after three desorption-regeneration cycles. Most importantly, FeS@NBC_BM was found to achieve Cr(VI) elimination not only by electrostatic attraction, ion exchange and complexation, but also by electrons-triggered reduction provided by different species of N, Fe²⁺ as well as S(Ⅱ). Meantime, pore filling, hydrogen bonding, and π-π stacking interactions were demonstrated to contribute to TC adsorption. These results suggested the co-modification of N-doping and FeS loading by ball milling as an innovative decorating method for biochar to adsorptive purification of Cr(VI) and TC-contaminated water.

Facile preparation of 3D porous agar-based heteroatom-doped carbon aerogels for high-energy density supercapacitors

The fabrication of heteroatom-doped porous carbon materials with high electrical conductivity and large specific surface area via an environmentally friendly route is critical and challenging. Herein, nitrogen and oxygen co-doped agar porous carbon (APC) was developed for supercapacitors via a one-step carbonization method with agar as the raw material and ammonia as the activator and nitrogen source. APC outperformed pectin porous carbon, tamarind porous carbon, and the previously reported carbon-based supercapacitors with a high capacitance retention of 72% even from 0.5 A g-1 to 20 A g-1 and excellent cycling stability in 6 M KOH solution (retained after 10 000 cycles) with a rate of over 98.5%. Furthermore, the APC electrode-based symmetric device exhibited an impressive energy density of 20.4 W h kg-1 and an ultra-high power density of 449 W kg-1 in 1 M Na2SO4 electrolyte together with excellent cycling stability (103.2% primary capacitance retentivity after 10 000 cycles). This study offers a novel method for the synthesis of nitrogen heteroatom-doped hierarchical porous carbon materials for performance-enhanced energy storage devices.

Integrating Bi@C Nanospheres in Porous Hard Carbon Frameworks for Ultrafast Sodium Storage

Sodium-ion batteries (SIBs) have emerged as an alternative technology because of their merits in abundance and cost. Realizing their real applications, however, remains a formidable challenge. One is that among the limitations of anode materials, the alloy-type candidates tolerate fast capacity fading during cycling. Here, a 3D framework superstructure assembled with carbon nanobelt arrays decorated with a metallic bismuth (Bi) nanospheres coated carbon layer by thermolysis of Bi-based metal-organic framework nanorods is synthesized as an anode material for SIBs. Due to the unique structural superiority, the anode design promotes excellent sodium-storage performance in terms of high capacity, excellent cycling stability, and ultrahigh rate capability up to 80 A g^-1 with a capacity of 308.8 mAh g^-1 . The unprecedented sodium-storage ability is not only attributed to the unique hybrid architecture, but also to the production of a homogeneous and thin solid electrolyte interface layer and the formation of uniform porous nanostructures during cycling in the ether-based electrolyte. Importantly, deeper understanding of the underlying cause of the performance improvement is illuminated, which is vital to provide the theoretical basis for application of SIBs.

Optically Encodable and Erasable Multilevel Nonvolatile Flexible Memory Device Based on Metal-Organic Frameworks

Multilevel and flexible nonvolatile memory (NVM) is a promising candidate for data storage in next-generation devices but its high bias and low mobility of conducting channels are often its drawbacks. In this study, we demonstrate a low bias of smaller than 0.1 V and a high-mobility graphene layer as a conducting channel for flexible optoelectronic NVM based on a composite thin film of indium-based MOF-derived InCl₃ and 4,4-oxydiphthalic anhydride (odpta), Na[In₃(odpt)₂(OH)₂(H₂O)₂](H₂O)₄, and reduced graphene oxide (rGO). The optoelectronic NVM device can be encoded and erased optically by ultraviolet (UV) light and visible light, respectively. Our device also achieves memory states over 192 (6-bit storage) distinct levels, which can emerge as mass data storage. It also shows an excellent endurance of write-erase cycles under irradiation with a laser of varying wavelengths, the mechanical stability of more than 1000 bending cycles, and stable retention for longer than 10 000 s. These results open an alternative route for developing low bias and innovative optoelectronic technologies.

Covalent Triazine Frameworks and Porous Carbons: Perspective from an Azulene-Based Case

Covalent triazine frameworks (CTFs) are among the most valuable frameworks owing to many fantastic properties. However, molten salt-involved preparation of CTFs at 400-600 °C causes debate on whether CTFs represent organic frameworks or carbon. Herein, new CTFs based on the 1,3-dicyanoazulene monomer (CTF-Azs) are synthesized using molten ZnCl₂ at 400-600 °C. Chemical structure analysis reveals that the CTF-Az prepared at low temperature (400 °C) exhibits polymeric features, whereas those prepared at high temperatures (600 °C) exhibit typical carbon features. Even after being treated at even higher temperatures, the CTF-Azs retain their rich porosity, but the polymeric features vanish. Although structural de-conformation is a widely accepted outcome in polymer-to-carbon rearrangement processes, the study evaluates such processes in the context of CTF systems. A proof-of-concept study is performed, observing that the as-synthesized CTF-Azs exhibit promising performance as cathodes for Li- and K-ion batteries. Moreover, the as-prepared NPCs exhibit excellent catalytic oxygen reduction reaction (ORR) performance; hence, they can be used as air cathodes in Zn-air batteries. This study not only provides new building blocks for novel CTFs with controllable polymer/carbon features but also offers insights into the formation and structure transformation history of CTFs during thermal treatment.

Preparation of the porous carbon-based solid acid from starch for efficient degradation of chitosan to D-glucosamine

Effective degradation of chitosan to D-glucosamine is considered to make a great contribution for the development of the medical industry. To address this issue, a porous carbon-based solid acid catalyst (PCSA) functionalized with -OH, -COOH and -SO₃H groups was successfully prepared. Typically, the physicochemical properties of PCSA were deeply determined by a series of characterization technique including FT-IR, TGA, RM, NH₃-TPD, SEM and Element Analysis. Moreover, the catalytic performances of PCSA towards to D-glucosamine production from chitosan were evaluated. In particular, the effects of catalyst acid density, ratio of acidic groups, chitosan concentration, reaction temperature, reaction time and catalyst dosage on the yield of D-glucosamine were investigated in detail. Interestingly, the experimental results indicated that a yield of D-glucosamine as high as 90.5% was achieved, and no obvious deactivation occurred even after six consecutive cycles. In light of the advantages of superior activity/recyclability and low cost, the starch-derived solid acid developed in this work might possess the broad industrial application prospects.

N-Doped Carbon Nanorods from Biomass as a Potential Antidiabetic Nanomedicine

Insufficient glucose control remains a critical challenge for type 2 diabetes mellitus (T2DM) patients with currently used therapeutic drugs, which can also have detrimental side effects. The facile synthesis of nitrogen-doped carbon nanorods (N-CNRs) as therapeutic agents in a T2DM transgenic db/db mouse model is reported herein. N-CNRs are synthesized from silkworm powder without the assistance of any template and possess a hollow graphitic nature, rough surface, and good aqueous solubility, which make them ideal candidates for fabricating nanomedicines. N-CNRs are employed to reduce fasting blood glucose and ameliorate serum biomarker levels linked to oxidative stress and inflammation. Interestingly, through the downregulation of enhanced expression of glutathione peroxidase, superoxide dismutase, and catalase as well as inflammatory responses, N-CNRs reverse pancreatic dysfunction and normalize the secretory functions of pancreatic cells. Moreover, hepatic steatosis is attenuated by downregulating lipogenesis and increasing fatty acid oxidation. This finding may help in designing novel therapeutics for T2DM treatment.

Fungus-Based MnO/Porous Carbon Nanohybrid as Efficient Laccase Mimic for Oxygen Reduction Catalysis and Hydroquinone Detection

Developing efficient laccase-mimicking nanozymes via a facile and sustainable strategy is intriguing in environmental sensing and fuel cells. In our work, a MnO/porous carbon (MnO/PC) nanohybrid based on fungus was synthesized via a facile carbonization route. The nanohybrid was found to possess excellent laccase-mimicking activity using 2,2′-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the substrate. Compared with the natural laccase and reported nanozymes, the MnO/PC nanozyme had much lower K_m value. Furthermore, the electrochemical results show that the MnO/PC nanozyme had high electrocatalytic activity toward the oxygen reduction reaction (ORR) when it was modified on the electrode. The hybrid nanozyme could catalyze the four-electron ORR, similar to natural laccase. Moreover, hydroquinone (HQ) induced the reduction of oxABTS and caused the green color to fade, which provided colorimetric detection of HQ. A desirable linear relationship (0–50 μM) and detection limit (0.5 μM) were obtained. Our work opens a simple and sustainable avenue to develop a carbon–metal hybrid nanozyme in environment and energy applications.