Nanostructured carbon and carbon nanocomposites for electrochemical energy storage applications

A Review of Carbon Nanofiber Materials for Dendrite-Free Lithium-Metal Anodes

Lithium metal is regarded as ideal anode material due to its high theoretical specific capacity and low electrode potential. However, the uncontrollable growth of lithium dendrites seriously hinders the practical application of lithium-metal batteries (LMBs). Among various strategies, carbon nanofiber materials have shown great potential in stabilizing the lithium-metal anode (LMA) due to their unique functional and structural characteristics. Here, the latest research progress on carbon nanofibers (CNFs) for LMA is systematically reviewed. Firstly, several common preparation techniques for CNFs are summarized. Then, the development prospects, strategies and the latest research progress on CNFs for dendrite-free LMA are emphatically introduced from the perspectives of neat CNFs and CNF-based composites. Finally, the current challenges and prospects of CNFs for stabilizing LMA are summarized and discussed. These discussions and proposed strategies provide new ideas for the development of high-performance LMBs.

p-n heterogeneous Sb2S3/SnO2 quantum dot anchored reduced graphene oxide nanosheets for high-performance lithium-ion batteries

Antimony sulfide (Sb2S3) has a high theoretical specific capacity due to its two reaction mechanisms of conversion and alloying during the Li+-(de)intercalation process, thus becoming a promising lithium-ion battery (LIB) anode material. However, its poor inherent conductivity and large volume expansion during repeated Li+-(de)intercalation processes greatly hinder the in-depth development of Sb2S3 based LIB anode materials. Herein, an Sb2S3/SnO2@rGO composite was prepared by using an interface engineering technique involving metal-containing ionic liquid precursors, in which Sb2S3/SnO2 quantum dots (QDs) as p-n heterojunctions are uniformly anchored on the surface of reduced graphene oxide (rGO). The p-n heterogeneous interface between Sb2S3 and SnO2 QDs induces an internal electric field, promoting the electronic/ion transport during electrochemical reactions, and the QD-sized Sb2S3/SnO2 heterostructure with a larger surface area provides more active sites for Li+-(de)intercalation reactions. In addition, the rGO matrix acts as a buffer to prevent the aggregation of active Sb2S3 and SnO2 QDs, alleviate the volume expansion, and enhance the conductivity of the composite during repeated cycles. These advantages endow the designed Sb2S3/SnO2@rGO electrode with excellent reaction kinetics and good long cycling stability. As an anode material of LIBs, it can still provide a reversible specific capacity of 474 mA h g-1 after 2000 cycles at a high current density of 3.0 A g-1, which is superior to those of most of the previously reported Sb2S3-based carbon materials. The p-n heterostructure construction strategy of nano-metal sulfide/metal oxides in this work can provide inspiration for the design and synthesis of other advanced energy storage materials.

Blackberry Seeds-Derived Carbon as Stable Anodes for Lithium-Ion Batteries

The suitability of biocarbons derived from blackberry seeds as anode materials in lithium-ion batteries has been assessed for the first time. Blackberry seeds have antibacterial, anticancer, antidysentery, antidiabetic, antidiarrheal, and potent antioxidant properties and are generally used for herbal medical purposes. Carbon is extracted from blackberries using a straightforward carbonization technique and activated with KOH at temperatures 700, 800, and 900 °C. The physical characterization demonstrates that activated blackberry seeds-derived carbon at 900 °C (ABBSC-900 °C) have well-ordered graphene sheets with high defects compared to the ABBSC-700 °C and ABBSC-800 °C. It is discovered that an ABBSC-900 °C is mesoporous, with a notable Brunauer-Emmett-Teller surface area of 65 m2 g-1. ABBSC-900 has good electrochemical characteristics, as studied under 100 and 1000 mA g-1 discharge conditions when used as a lithium intercalating anode. Delivered against a 500 mA g-1 current density, a steady reversible capacity of 482 mA h g-1 has been achieved even after 200 cycles. It is thought that disordered mesoporous carbon with a large surface area account for the improved electrochemical characteristics of the ABBSC-900 anode compared to the other ABBSC-700 and ABBSC-800 carbons. The research shows how to use a waste product, ABBSC, as the most desired anode for energy storage applications.

Telluride-Based Materials: A Promising Route for High Performance Supercapacitors

As supercapacitor (SC) technology continues to evolve, there is a growing need for electrode materials with high energy/power densities and cycling stability. However, research and development of electrode materials with such characteristics is essential for commercialization the SC. To meet this demand, the development of superior electrode materials has become an increasingly critical step. The electrochemical performance of SCs is greatly influenced by various factors such as the reaction mechanism, crystal structure, and kinetics of electron/ion transfer in the electrodes, which have been challenging to address using previously investigated electrode materials like carbon and metal oxides/sulfides. Recently, tellurium and telluride-based materials have garnered increasing interest in energy storage technology owing to their high electronic conductivity, favorable crystal structure, and excellent volumetric capacity. This review provides a comprehensive understanding of the fundamental properties and energy storage performance of tellurium- and Te-based materials by introducing their physicochemical properties. First, we elaborate on the significance of tellurides. Next, the charge storage mechanism of functional telluride materials and important synthesis strategies are summarized. Then, research advancements in metal and carbon-based telluride materials, as well as the effectiveness of tellurides for SCs, were analyzed by emphasizing their essential properties and extensive advantages. Finally, the remaining challenges and prospects for improving the telluride-based supercapacitive performance are outlined.

Preparation of MoFs-Derived Cobalt Oxide/Carbon Nanotubes Composites for High-Performance Asymmetric Supercapacitor

Metal–organic frameworks (MOFs)-derived metallic oxide compounds exhibit a tunable structure and intriguing activity and have received intensive investigation in recent years. Herein, this work reports metal–organic frameworks (MOFs)-derived cobalt oxide/carbon nanotubes (MWCNTx@Co3O4) composites by calcining the MWCNTx@ZIF-67 precursor in one step. The morphology and structure of the composite were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) characterization. The compositions and valence states of the compounds were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Benefiting from the structurally stable MOFs-derived porous cobalt oxide frameworks and the homogeneous conductive carbon nanotubes, the synthesized MWCNTx@Co3O4 composites display a maximum specific capacitance of 206.89 F·g−1 at 1.0 A·g−1. In addition, the specific capacitance of the MWCNT3@Co3O4//activated carbon (AC) asymmetric capacitor reaches 50 F·g−1, and has an excellent electrochemical performance. These results suggest that the MWCNTx@Co3O4 composites can be a potential candidate for electrochemical energy storage devices.

Advances in Electrospun Materials and Methods for Li-Ion Batteries

Electronic devices commonly use rechargeable Li-ion batteries due to their potency, manufacturing effectiveness, and affordability. Electrospinning technology offers nanofibers with improved mechanical strength, quick ion transport, and ease of production, which makes it an attractive alternative to traditional methods. This review covers recent morphology-varied nanofibers and examines emerging nanofiber manufacturing methods and materials for battery tech advancement. The electrospinning technique can be used to generate nanofibers for battery separators, the electrodes with the advent of flame-resistant core-shell nanofibers. This review also identifies potential applications for recycled waste and biomass materials to increase the sustainability of the electrospinning process. Overall, this review provides insights into current developments in electrospinning for batteries and highlights the commercialization potential of the field.

Synthesis, surface modifications, and biomedical applications of carbon nanofibers: Electrospun vs vapor-grown carbon nanofibers

Engineered nanostructures are materials with promising properties, enabled by precise design and fabrication, as well as size-dependent effects. Biomedical applications of nanomaterials in disease-specific prevention, diagnosis, treatment, and recovery monitoring require precise, specific, and sophisticated approaches to yield effective and long-lasting favorable outcomes for patients. In this regard, carbon nanofibers (CNFs) have been indentified due to their interesting properties, such as good mechanical strength, high electrical conductivity, and desirable morphological features. Broadly speaking, CNFs can be categorized as vapor-grown carbon nanofibers (VGCNFs) and carbonized CNFs (e.g., electrospun CNFs), which have distinct microstructure, morphologies, and physicochemical properties. In addition to their physicochemical properties, VGCNFs and electrospun CNFs have distinct performances in biomedicine and have their own pros and cons. Indeed, several review papers in the literature have summarized and discussed the different types of CNFs and their performances in the industrial, energy, and composites areas. Crucially however, there is room for a comprehensive review paper dealing with CNFs from a biomedical point of view. The present work therefore, explored various types of CNFs, their fabrication and surface modification methods, and their applications in the different branches of biomedical engineering.

Electrochemical sensors based on carbon nanostructures for the analysis of bisphenol A-A review

Overuse of Bisphenol A (BPA), a proven endocrine disruptor, has become a serious public health problem across the world. It has the potential to harm both the environment and human health, notably reproductive disorders, heart disease, and diabetes. Accordingly, much attention has been paid to the detection of BPA to promote food safety and environmental health. Carbon based nanostructures have proven themselves well in a variety of applications, such as energy storage, catalysis and sensors, due to their remarkable properties. Therefore, researchers have recently focused on fabricating electrochemical BPA sensors based on carbon nanostructures due to their unique advantages, such as real-time monitoring, simplicity, high selectivity, high sensitivity and easy operation. The purpose of the current review was to summarize the recent findings on carbon nanostructures for electrochemically sensing the BPA, as well as relevant future prospects and ongoing challenges.

Enhanced electrocatalytic performance of N-doped carbon xerogels obtained through dual nitrogen doping for the oxygen reduction reaction

The development of high efficiency and low-cost electrocatalysts for the oxygen reduction reaction (ORR) is urgently desired for many energy storage and conversion systems. Nitrogen-doped carbon xerogels (NCXs) which have been successfully applied as effective electrocatalysts for the ORR have continued to attract attention due to their competitive price and tunable surface chemistry. A new dual N-doped NCX (NCoNC) electrocatalyst is fabricated as a carbon based catalyst though a facile impregnation of peptone in a precursor and ammonia etching pyrolysis method. XPS analysis demonstrates that the NCoNC electrocatalyst not only has a high N doping amount, but also has an optimized chemical state composition of N doping, which play an important role in improving the microstructure and catalytic performance of the catalysts. XRD and HRTEM results show that the doped metal nano-particles are coated with a double carbon layer of graphene carbon (inner layer) and amorphous carbon (outer layer) forming serrated edges that facilitate the ORR process. The as-obtained NCoNC catalyst exhibits good electrocatalytic performance and excellent stability for the ORR in both acidic and alkaline environments. In particular, in alkaline electrolyte, the decrements of both the limiting current density and the half-wave potential of the NCoNC catalyst were significantly lower than those of a commercial Pt/C catalyst during accelerated aging tests. When serving as an air electrode in Zn–air batteries, the catalyst also exhibits superior catalytic performance with a peak power density of 78.2 mW cm⁻² and a stable open-circuit voltage of 1.37–1.43 V. This work presents a novel tactic to regulate the microstructure and composition of carbon-based electrocatalysts by the facile and scalable dual-effect nitrogen doping method which may be conducive to promoting and developing highly efficient and promising electrocatalysts for the ORR.

This work presents a novel tactic to regulate the microstructure and composition of carbon-based catalysts by the facile and scalable dual-effect nitrogen doping method which may be conducive to promoting highly efficient electrocatalysts for ORR.

Renewable spent mushroom compost-derived carbon for solid-state supercapacitors as a sustainable alternative

The systematic and stepwise formation of spent mushroom compost-derived activated carbon (SMC), electrode assembly, and supercapacitor performance were studied.

Atomically dispersed metal catalysts on nanodiamond and its derivatives: synthesis and catalytic application

Atomically dispersed metal catalysts (ADMCs) have attracted increasing interest in the field of heterogeneous catalysis. As sub-nanometric catalysts, ADMCs have exhibited remarkable catalytic performance in many reactions. ADMCs are classified into two categories: single atom catalysts (SACs) and atomically dispersed clusters with a few atoms. To stabilize the highly active ADMCs, nanodiamond (ND) and its derivatives (NDDs) are promising supports. In this Feature Article, we have introduced the advantages of NDDs with a highly curved surface and tunable surface properties. The controllable defective sites and oxygen functional groups are known as the anchoring sites for ADMCs. Tunable surface acid-base properties enable ADMCs supported on NDDs to exhibit unique selectivity towards target products and an extended lifetime in many reactions. In addition, we have firstly overviewed the recent advances in the synthesis strategies for effectively fabricating ADMCs on NDDs, and further discussed how to achieve the atomic dispersion of metal precursors and stabilize the as-formed metal atoms against migration and agglomeration based on NDDs. And then, we have also systematically summarized the advantages of ADMCs supported on NDDs in reactions, including hydrogenation, dehydrogenation, aerobic oxidation and electrochemical reaction. These reactions can also effectively guide the design of ADMCs. The recent progress in understanding the effect of structure of active centers and metal-support interactions (MSIs) on the catalytic performance of ADMCs is particularly highlighted. At last, the possible research directions in ADMCs are forecasted.

Stimuli-responsive nanoparticles based on poly acrylic derivatives for tumor therapy

Serve side effects caused by discriminate damage of chemotherapeutic drugs to normal cell and cancer cells remain a main obstacle in clinic. Hence, continuous efforts have been made to find ways to effectively enhance drug delivery and reduce side effects. Recent decades have witnessed impressive progresses in fighting against cancer, with improved understanding of tumor microenvironment and rapid development in nanoscale drug delivery system (DDS). Nanocarriers based on biocompatible materials provide possibilities to improve antitumor efficiency and minimize off-target effects. Among all kinds of biocompatible materials applied in DDS, polymeric acrylic derivatives such as poly(acrylamide), poly(acrylic acid), poly(N-isopropylacrylamide) present inherent biocompatibility and stimuli-responsivity, and relatively easy to be functionalized. Furthermore, nanocarrier based on polymeric acrylic derivatives have demonstrated high drug encapsulation, improved uptake efficiency, prolonged circulation time and satisfactory therapeutic outcome in tumor. In this review, we aim to discuss recent progress in design and development of stimulus-responsive poly acrylic polymer based nanocarriers for tumor targeting drug delivery.

Hierarchical Aluminum Vanadate Microspheres with Structural Water: High-Performance Cathode Materials for Aqueous Rechargeable Zinc Batteries

Controlling morphology, adopting metal cations and introducing crystal water are three effective strategies to improve the electrochemical performance of various battery electrodes. However, the effects of simultaneously applying these three strategies to aqueous rechargeable zinc batteries (ARZBs) are rarely demonstrated. Herein, hierarchical H₁₁ Al₂ V₆ O_23.2 (HAVO) microspheres were successfully prepared using a simple hydrothermal method, and used as cathode material for ARZBs. The as-prepared HAVO microspheres exhibited superior electrochemical performance than the dehydrated AlV₃ O₉ (AVO) microspheres, i. e. they have a larger specific capacity of 390.4 mA h g^-1 at 100 mA g^-1 , a better rate capability of 191.4 mA h g^-1 at 5000 mA g^-1 and a higher cycling stability of up to 1000 cycles with a capacity retention of 80.9 %. The excellent electrochemical performance of HAVO is due to the synergistic effects of the shortened ion diffusion distance in primary HAVO nanosheets, the improved electronic conductivity, and structural stability by adopting Al³⁺ into the lattice, the enhanced charge transfer properties and ion diffusion coefficient of the electrode due to the existence of crystal water. Therefore, this work may offer a new route for the design and synthesis of more advanced electrode materials for ARZBs.

Transparent and flexible high-power supercapacitors based on carbon nanotube fibre aerogels

In this work, we report the fabrication of continuous transparent and flexible supercapacitors by depositing a CNT network onto a polymer electrolyte membrane directly from an aerogel of ultra-long CNTs produced floating in the gas phase. The supercapacitors show a combination of a power density of 1370 kW kg-1 at high transmittance (ca. 70%), and high electrochemical stability during extended cycling (>94% capacitance retention over 20 000 cycles) and against repeated 180° flexural deformation. They represent a significant enhancement of 1-3 orders of magnitude compared to prior state-of-the-art transparent supercapacitors based on graphene, CNTs, and rGO. These features mainly arise from the exceptionally long length of CNTs, which makes the material behave as a bulk conductor instead of an aspect ratio-limited percolating network, even for electrodes with >90% transparency. The electrical and capacitive figures-of-merit for the transparent conductor are FoMe = 2.7, and FoMc = 0.46 F S-1 cm-2 respectively.

3D hierarchical self-supported NiO/Co3O4@C/CoS2 nanocomposites as electrode materials for high-performance supercapacitors

Multi-dimensional nanomaterials have drawn great interest for application in supercapacitors due to their large accessible surface area. However, the achievements of superior rate capability and cycle stability are hindered by their intrinsic poor electronic/ionic conductivity and the erratic structure. Herein, we develop a three-dimensional hierarchical self-supported NiO/Co₃O₄@C/CoS₂ hybrid electrode, in which NiO/Co₃O₄ nanosheets are in situ grown on a nickel foam substrate and combined with CoS₂ nanospheres through a carbon medium. The hybrid electrode has a high specific capacity of ∼1025 C g^-1 at 1 A g^-1 with a superior rate performance of ∼74% capacity retention even at a current density of 30 A g^-1. Moreover, the assembled NiO/Co₃O₄@C/CoS₂//AC hybrid supercapacitor achieves excellent performance with a maximum voltage of 1.64 V and a high energy density of 62.83 W h kg^-1 at a power density of 824.99 W kg^-1 and excellent cycle stability performance with a capacity retention of ∼92% after 5000 cycles. The high electrochemical performance of the hybrid supercapacitor is mainly attributed to the porous structure of the NiO/Co₃O₄@C nanosheets and CoS₂ nanospheres and intimate integration of active species. The rational strategy for the combination of various earth-abundant nanomaterials paves a new way for energy storage materials.

A Holey Graphene Additive for Boosting Performance of Electric Double-Layer Supercapacitors

We demonstrate a facile and effective method, which is low-cost and easy to scale up, to fabricate holey graphene nanosheets (HGNSs) via ultrafast heating during synthesis. Various heating temperatures are used to modify the material properties of HGNSs. First, we use HGNSs as the electrode active materials for electric double-layer capacitors (EDLCs). A synthesis temperature of 900 °C seems to be optimal, i.e., the conductivity and adhesion of HGNSs reach a compromise. The gravimetric capacitance of this HGNS sample (namely HGNS-900) is 56 F·g⁻¹. However, the volumetric capacitance is low, which hinders its practical application. Secondly, we incorporate activated carbon (AC) into HGNS-900 to make a composite EDLC material. The effect of the AC:HGNS-900 ratio on the capacitance, high-rate performance, and cycling stability are systematically investigated. With a proper amount of HGNS-900, both the electrode gravimetric and volumetric capacitances at high rate charging/discharging are clearly higher than those of plain AC electrodes. The AC/HGNS-900 composite is a promising electrode material for nonaqueous EDLC applications.

C60(OH)12 and Its Nanocomposite for High-Performance Lithium Storage

Organic carbon materials, such as graphene and nanotubes, with a high specific capacity show promise in improving the energy density for lithium ion batteries (LiBs). Here, we report on the synthesis and characterization of C₆₀(OH)₁₂ and the C₆₀(OH)₁₂/graphene oxide (GO) composite and demonstrate their use as anode materials in LiBs. We find that the C₆₀(OH)₁₂/GO composite forms due to the chemical reactions between the carboxyl and epoxy groups of GO and the hydroxyl of C₆₀(OH)₁₂ nanoparticles and that C₆₀(OH)₁₂ uniformly grows on the surface of GO nanosheets. Using a suite of spectroscopy probes, we unequivocally show the mixing between C₆₀(OH)₁₂ and GO at the molecular level, which leads to superior battery performances. This composite has a reversible capacity of 1596 mAh g^-1 at 0.2 A g^-1, higher than the capacities of C₆₀(OH)₁₂ and GO. This composite has a superior cycling stability and excellent rate performance, making it a promising organic anode material for high-performance LiBs.

Binder-Free Nickel Oxide Lamellar Layer Anchored CoOx Nanoparticles on Nickel Foam for Supercapacitor Electrodes

To enhance the connection of electroactive materials/current collector and accelerate the transport efficiency of the electrons, a binder-free electrode composed of nickel oxide anchored CoO_x nanoparticles on modified commercial nickel foam (NF) was developed. The nickel oxide layer with lamellar structure which supplied skeleton to load CoO_x electroactive materials directly grew on the NF surface, leading to a tight connection between the current collector and electroactive materials. The fabricated electrode exhibits a specific capacitance of 475 F/g at 1 mA/cm². A high capacitance retention of 96% after 3000 cycles is achieved, attributed to the binding improvement at the current collector/electroactive materials interface. Moreover, an asymmetric supercapacitor with an operating voltage window of 1.4 V was assembled using oxidized NF anchored with cobalt oxide as the cathode and activated stainless steel wire mesh as the anode. The device achieves a maximum energy density of 2.43 Wh/kg and power density of 0.18 kW/kg, respectively. The modified NF substrate conducted by a facile and effective electrolysis process, which also could be applied to deposit other electroactive materials for the energy storage devices.

Electrospun CNF Supported Ceramics as Electrochemical Catalysts for Water Splitting and Fuel Cell: A Review

With the per capita growth of energy demand, there is a significant need for alternative and sustainable energy resources. Efficient electrochemical catalysis will play an important role in sustaining that need, and nanomaterials will play a crucial role, owing to their high surface area to volume ratio. Electrospun nanofiber is one of the most promising alternatives for producing such nanostructures. A section of key nano-electrocatalysts comprise of transition metals (TMs) and their derivatives, like oxides, sulfides, phosphides and carbides, etc., as well as their 1D composites with carbonaceous elements, like carbon nanotubes (CNTs) and carbon nanofiber (CNF), to utilize the fruits of TMs’ electronic structure, their inherent catalytic capability and the carbon counterparts’ stability, and electrical conductivity. In this work, we will discuss about such TM derivatives, mostly TM-based ceramics, grown on the CNF substrates via electrospinning. We will discuss about manufacturing methods, and their electrochemical catalysis performances in regards to energy conversion processes, dealing mostly with water splitting, the metal–air battery fuel cell, etc. This review will help to understand the recent evolution, challenges and future scopes related to electrospun transition metal derivative-based CNFs as electrocatalysts.

Nitrogen-Doped Graphene-Buffered Mn2 O3 Nanocomposite Anodes for Fast Charging and High Discharge Capacity Lithium-Ion Batteries

Mn₂ O₃ is a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity and low discharge potential. However, low electronic conductivity and capacity fading limits its practical application. In this work, Mn₂ O₃ with 1D nanowire geometry is synthesized in neutral aqueous solutions by a facile and effective hydrothermal strategy for the first time, and then Mn₂ O₃ nanoparticle and nitrogen-doped reduced graphene oxide (N-rGO) are composited with Mn₂ O₃ nanowires (Mn₂ O₃ -GNCs) to enhance its volume utilization and conductivity. When used as an anode material for LIBs, the Mn₂ O₃ -GNCs exhibit high reversible capacity (1350 mAh g^-1 ), stable cycling stability, and good rate capability. Surprisingly, the Mn₂ O₃ -GNC electrodes can also show fast charging capability; even after 200 cycles (charge: 10 A g^-1 ; discharge: 0.5 A g^-1 ), its discharge capacity can also keep at ≈500 mAh g^-1 . In addition, the Mn₂ O₃ -GNCs also have considerable full cell and supercapacitor performance. The excellent electrochemical performances can be ascribed to the N-rGO network structure and 1D nanowire structure, which can ensure fast ion and electron transportation.

Atomic Layer Deposition of Inorganic Films for the Synthesis of Vertically Aligned Carbon Nanotube Arrays and Their Hybrids

Vertically aligned carbon nanotube arrays (VACNTs) have many excellent properties and show great potential for various applications. Recently, there has been a desire to grow VACNTs on nonplanar surfaces and synthesize core-sheath-structured VACNT–inorganic hybrids. To achieve this aim, atomic layer deposition (ALD) has been extensively applied, especially due to its atomic-scale thickness controllability and excellent conformality of films on three-dimensional (3D) structures with high aspect ratios. In this paper, the ALD of catalyst thin films for the growth of VACNTs, such as Co3O4, Al2O3, and Fe2O3, was first mentioned. After that, the ALD of thin films for the synthesis of VACNT–inorganic hybrids was also discussed. To highlight the importance of these hybrids, their potential applications in supercapacitors, solar cells, fuel cells, and sensors have also been reviewed.

1D Carbon-Based Nanocomposites for Electrochemical Energy Storage

Electrochemical energy storage (EES) devices have attracted immense research interests as an effective technology for utilizing renewable energy. 1D carbon-based nanostructures are recognized as highly promising materials for EES application, combining the advantages of functional 1D nanostructures and carbon nanomaterials. Here, the recent advances of 1D carbon-based nanomaterials for electrochemical storage devices are considered. First, the different categories of 1D carbon-based nanocomposites, namely, 1D carbon-embedded, carbon-coated, carbon-encapsulated, and carbon-supported nanostructures, and the different synthesis methods are described. Next, the practical applications and optimization effects in electrochemical energy storage devices including Li-ion batteries, Na-ion batteries, Li-S batteries, and supercapacitors are presented. After that, the advanced in situ detection techniques that can be used to investigate the fundamental mechanisms and predict optimization of 1D carbon-based nanocomposites are discussed. Finally, an outlook for the development trend of 1D carbon-based nanocomposites for EES is provided.

Hollow Carbon Nanospheres with Developed Porous Structure and Retained N Doping for Facilitated Electrochemical Energy Storage

Development of highly porous carbons with abundant surface functionalities and well-defined nanostructure is of significance for many important electrochemical energy storage systems. However, porous carbons suffer from a compromise between porosity, doped functionality, and nanostructure that have thus far restricted their performances. Here, we report the design of highly porous, nitrogen-enriched hollow carbon nanospheres (PN-HCNs) by an interfacial copolymerization strategy followed by NH₃-assisted carbonization, and further demonstrate their significance and effectiveness in enhancing the electrochemical performances. The PN-HCN simultaneously delivers a large surface area (1237 m² g^-1) and high N functionalities (6.25 atom %) with a remarkable efficiency of the surface area increase to N loss ratio enabled by NH₃ treatment while inheriting the hollow nanospherical structure. Accordingly, owing to the enhanced surface area and retained N doping, the prepared PN-HCN demonstrates outstanding electrochemical performances as a cathode host in lithium-sulfur batteries, including a near-to-theoretical capacity of 1620 mAh g^-1, high rate capability and good cycling stability (789 mAh g^-1 at 0.5C after 200 cycles). These results are superior to those of HCN without NH₃ treatment. Also, PN-HCN exhibits superior capacitances (203 F g^-1) and fast ion transport ability in supercapacitors. Our finding shows the simultaneous achievement of both highly porous structures and sufficient N functionalities for high-performance applications.

Dynamics of [Pyr13][Tf2N] ionic liquid confined to carbon black

The intrinsic ionic nature of room temperature ionic liquids (RTILs) bears the potential to replace classical aqueous electrolytes in electrochemical applications, for example in metal-air batteries. For a systematic adjustment of RTIL properties in porous cathodes, the ionic arrangement under confinement is of prime importance. Using spectrally resolved pulsed gradient stimulated echo nuclear magnetic resonance (PGSTE-NMR) and spin-lattice NMR relaxation time (T₁) distributions, the dynamics of 1-methyl-1-propylpyrrolidiniumbis(trifluoromethylsulfonyl)imide ([Pyr₁₃][Tf₂N]) confined to carbon black were investigated. A considerable dependence of the [PYR₁₃] mobility on the loading fraction of the carbon black pore space was found. There is evidence for a preferential layering of the RTIL adjacent to the carbon surface and a dependence of the ionic configuration on the local structure of the carbon surface. The inversion efficiency of inversion-recovery T₁ data indicates a quasi-stationary layer at the carbon surface with solid-like properties, where the bulk-like properties of the RTIL are adopted as the distance to the surface increases. From the NMR diffusion data an intermediate layer between the quasi-stationary and the bulk-like RTIL is evident. This layer shows a particularly strong pore space loading dependence. While it has an anisotropic, two-dimensional mobility with reduced diffusion perpendicular to the surface at any loading, when it interfaces a gas phase at low loading its mobility is higher than bulk diffusion by up to an order of magnitude and chemical exchange with other layers is low. This layer appears to be of particular importance for the ion exchange between RTIL environments with different spacing from the carbon surface and hence crucial for the overall dynamics of RTILs in the investigated porous environment.

Synthesis of Free-Standing Flexible rGO/MWCNT Films for Symmetric Supercapacitor Application

Herein, we report a novel, simple, and cost-effective way to synthesize flexible and conductive rGO and rGO/MWCNT freestanding films. The effects of MWCNT addition on the electrochemical performance of rGO/MWCNT nanocomposite films are investigated in some strong base aqueous electrolytes, such as KOH, LiOH, and NaOH via three-electrode system. The supercapacitor behavior of the films is probed via cyclic voltammetry, galvanostatic charging-discharging, and electrochemical impedance spectroscopy. The structural and morphological studies of the films are performed by X-ray diffractometer, Raman spectrometer, surface area analyzer, thermogravimetric analysis, field emission scanning electron microscope and transmission electron microscope. The rGO/MWCNT film synthesized with 10 wt% MWCNTs (GP10C) exhibits high specific capacitance of 200 Fg-1, excellent cyclic stability with 92% retention after 15,000 long cycle test, small relaxation time constant (~ 194 ms), and high diffusion coefficient (7.8457 × 10-9 cm2 s-1) in 2 M KOH electrolyte. Furthermore, the symmetric supercapacitor coin cell with GP10C as both anode and cathode using 2 M KOH as electrolyte demonstrates high energy density of 29.4 Whkg-1 and power density of 439 Wkg-1 at current density 0.1 Ag-1 and good cyclic stability with 85% retention of the initial capacitance at 0.3 Ag-1 after 10,000 cycles. Such a high performance of the GP10C film in the supercapacitor can be ascribed to the large surface area and small hydration sphere radius and high ionic conductivity of K+ cations in KOH electrolyte.

The preparation of liquefied bio-stalk carbon nanofibers and their application in supercapacitors

Carbon nanofibers (CNFs) have been widely used in electrochemical energy storage devices because of their excellent conductivity, extremely large surface area and structural stability. Herein, we obtained a viscous, liquefied bio-stalk carbon via the simple chemical treatment of biomass, and mixed it with polyacrylonitrile to prepare a spinning solution. Subsequent electrospinning and high temperature activation resulted in the successful preparation of liquefied lignin-based activated carbon nanofibers. The as-prepared liquefied bio-stalk carbon nanofibers exhibited an outstanding electrochemical performance (specific capacitance of 273 F g-1 at 0.5 A g-1 current density), and a capacitance retention of 210 F g-1 even under a large current density of 10 A g-1. Besides its high specific capacitance and outstanding rate capability, the symmetrical supercapacitor cell based on the liquefied carbon-based nanofiber electrodes also exhibited an excellent cycling performance with 92.76% capacitance retention after 5000 charge-discharge cycles. This study provides a new strategy for the future development of supercapacitor electrode materials and enhances the development of biomass energy.

ZIF-67-Derived N-Doped Co/C Nanocubes as High-Performance Anode Materials for Lithium-Ion Batteries

Co nanoparticles embedded in nitrogen-doped carbon nanocubes (Co/NCs) for applications as anode materials in rechargeable lithium-ion batteries were synthesized by calcining Co-based metal-organic framework. Sizes of Co nanoparticles were ∼15 nm according to X-ray diffraction (XRD) and transmission electron microscopy. Electrochemical performances of the as-prepared anode nanocube composite at 700 °C showed a high initial capacity of 1375.1 mAh g^-1 in the voltage range of 0.01-3.0 V at the current rate of 0.1 A g^-1. After 100 cycles, capacity remained at 688.6 mAh g^-1. Thereinto, the role of Co nanoparticles in electrochemical reaction was also elucidated by in situ XRD experiment. Capacity increase of Co/NCs at the high currents was observed, which are potentially caused by the activation of electrode and pseudocapacitance during cycling. High surface area and abundant mesopores contributed to the improved electrochemical performances of the anode, providing numerous pathways and sites for Li⁺ transfer and storage and accordingly contributing to pseudocapacitance capacity.

Hybrid Catalysts for CO2 Conversion into Cyclic Carbonates

The conversion of carbon dioxide into valuable chemicals such as cyclic carbonates is an appealing topic for the scientific community due to the possibility of valorizing waste into an inexpensive, available, nontoxic, and renewable carbon feedstock. In this regard, last-generation heterogeneous catalysts are of great interest owing to their high catalytic activity, robustness, and easy recovery and recycling. In the present review, recent advances on CO2 cycloaddition to epoxide mediated by hybrid catalysts through organometallic or organo-catalytic species supported onto silica-, nanocarbon-, and metal–organic framework (MOF)-based heterogeneous materials, are highlighted and discussed.

Preparation of chrome-tanned leather shaving-based hierarchical porous carbon and its capacitance properties

Based on the complexes formed by the original Cr(iii) in chrome-tanned leather shavings and the carboxyl groups in collagen as raw materials, a chromium oxide-carbon composite material was formed by the high-temperature carbonization of chromium-tanned leather shavings, followed by the leaching of chrome oxide and activation by KOH. By this method, the hierarchical porous carbon with a high surface area doped with oxygen and nitrogen was prepared. The forming process of the hierarchical porous structure is discussed in detail. Through adjusting the mass ratio of KOH to carbon during the activation process, with a mass ratio of 2, the chromium-tanned leather shavings-based hierarchical porous carbon (called CTSHPC-2) was prepared with an optimal specific surface area (3211 m² g⁻¹) and a large volume ratio of mesopores to macropores (61.9%) as well as abundant oxygen (13.92 at%) and nitrogen (3.58 at%) functional groups. The results showed that CTSHPC-2 obtained a high specific capacitance of 335.5 F g⁻¹ at a current density of 0.5 A g⁻¹. In addition, it had higher rate performance, low resistance, and better cycle stability. Even when the current density is 10 A g⁻¹ over 5000 cycles, the specific capacity retention rate is 93.5%. Therefore, CTSHPC-2 is a promising electrode material for supercapacitors.

A chromium oxide-carbon composite material was formed by the high-temperature carbonization of chromium-tanned leather shavings, followed by the leaching of chrome oxide and activation by KOH.

Polymer network-derived nitrogen/sulphur co-doped three-dimensionally interconnected hierarchically porous carbon for oxygen reduction, lithium-ion battery, and supercapacitor

Rational design and simple synthesis of carbon-based materials with high electrocatalytic activity are essential for their practical applications in electrochemical energy conversion and storage devices. Herein, we report the synthesis of nitrogen, sulfur co-doped three-dimensional interconnected hierarchically porous carbon (NSHPC) by zinc acetate assisted pyrolysis of polymer networks. The thus-synthesized NSHPC has a specific surface area of 1057 cm² g⁻¹ with the coexistence of micro- and meso-pores. As metal-free electrocatalyst, the NSHPC exhibits a promising activity towards oxygen reduction reactions as evidenced by the slightly negative shift of half-wave potential compared with commercial Pt/C catalyst. The assembled lithium ion battery using NSHPC as anode delivers the reversible capacity of 740 and 470 mA h g⁻¹ at current densities of 2 and 5 A g⁻¹ without performance decay after 1000 charge–discharge cycles. Moreover, the assembled supercapacitor using NSHPC as electrode has the capacitance of 203 F g⁻¹ at 1 A g⁻¹.

Polymer networks are efficient precursors for large scale production of hierarchical porous carbon.

Porous Polymers as Multifunctional Material Platforms toward Task-Specific Applications

Exploring advanced porous materials is of critical importance in the development of science and technology. Porous polymers, being famous for their all-organic components, tailored pore structures, and adjustable chemical components, have attracted an increasing level of research interest in a large number of applications, including gas adsorption/storage, separation, catalysis, environmental remediation, energy, optoelectronics, and health. Recent years have witnessed tremendous research breakthroughs in these fields thanks to the unique pore structures and versatile skeletons of porous polymers. Here, recent milestones in the diverse applications of porous polymers are presented, with an emphasis on the structural requirements or parameters that dominate their properties and functionalities. The Review covers the following applications: i) gas adsorption, ii) water treatment, iii) separation, iv) heterogeneous catalysis, v) electrochemical energy storage, vi) precursors for porous carbons, and vii) other applications (e.g., intelligent temperature control textiles, sensing, proton conduction, biomedicine, optoelectronics, and actuators). The key requirements for each application are discussed and an in-depth understanding of the structure-property relationships of these advanced materials is provided. Finally, a perspective on the future research directions and challenges in this field is presented for further studies.