Freestanding Nitrogen-Doped Carbons with Hierarchical Porosity for Environmental Applications: A Green Templating Route with Bio-Based Precursors

Powdery hierarchical porous carbons serve as cost-effective, functional materials in various fields, namely energy storage, heterogeneous catalysis, electrochemistry, and water/wastewater treatment. Such powdered activated carbons (PAC) limit new module designs and require further preparation steps, for example, adding polymeric binders, to be shaped into a standalone geometry. Polymeric binders, however, can block PACs' catalytic and active sites and, more importantly, pose the risk of secondary pollution for environmental purposes, especially in the context of clean water supply. This study introduces a novel synthesis method for fabricating freestanding nitrogen-doped carbons with hierarchical porosity using chitosan and sucrose as green precursors. Chitosan supplies nitrogen and acts as a backbone, giving a freestanding geometry to the final product, and sucrose is a carbon-rich precursor. The proposed method employs ice- and hard-templating for macropores and mesopores and combines carbonization and activation steps with no required activating agent. Final freestanding carbons function as adsorbents for removing persistent pollutants, as binder-free electrodes with high specific surface area and capacitive current, and as tubular gas diffusion electrodes for oxygen reduction reactions. These freestanding carbons enable new module designs and can be scaled-up by numbering-up, serving as bio-based functional materials for a wide range of applications involving porous heteroatom-doped carbons.

Preparation of an N-doped mesoporous carbon sphere and sheet composite as a high-performance supercapacitor

Carbon-based materials with multidimensional structures generally exhibit improved properties compared with single-morphology carbon materials for various applications including catalysis, adsorption, and energy storage. Here, an N-doped mesoporous carbon sphere and sheet composite is prepared by a co-assembly strategy using an ionic liquid ([C18Mim]Br) as the structure-directing agent, ethylenediamine as the catalyst, tetraethyl orthosilicate as the pore-forming agent, and resorcinol formaldehyde resin as the carbon precursor. [C18Mim]Br and ethylenediamine not only induce formation of the unique structure but also lead to in situ nitrogen doping on the N-doped mesoporous carbon skeleton. The obtained N-doped mesoporous carbon shows a unique composite structure of thin sheets embedded with carbon spheres, having high a specific surface area and uniform mesopore distribution. When used as an electrode material, the N-doped mesoporous carbon shows a good specific capacity of 273 F g−1 at a current density of 0.5 A g−1 and a good rate capability (82.1% of the capacitance is retained at a high current density of 10 A g−1). Moreover, the N-doped mesoporous carbon exhibited ideal stability behavior (91.6% capacitive retention after 10,000 cycles), indicating a promising role as an electrode material for excellent performance supercapacitors.

The lightest solid meets the lightest gas: an overview of carbon aerogels and their composites for hydrogen related applications

Hydrogen, a renewable and recyclable energy, has been regarded as the best solution for global energy supply in the 21^st century. Hydrogen production, hydrogen storage and hydrogen sensing are three most important aspects for hydrogen economy. Interestingly, the lightest solid, carbon aerogels (CAs), has found wide applications in these aspects due to its unique characteristics including large specific surface area, hierarchical porous structure, high electrical conductivity, superb chemical stability, and low fabrication cost. Herein, various fabrication strategies of CAs are presented, and their applications in the three most important aspects are comprehensively reviewed. In addition, the challenges and prospects are also discussed. In the light of the recent progress in CAs for hydrogen-related applications, this review provides a comprehensive assessment on materials selection, synthesis, hydrogen adsorption characteristics of CAs and catalytic activity of CA-supported nanocatalysts, offering a strategic guide to build a close connection between CAs and hydrogen economy.

Co-doped carbon materials synthesized with polymeric precursors as bifunctional electrocatalysts

The design of stable and high performance metal free bifunctional electrocatalysts is a necessity in alkaline zinc–air batteries for oxygen reduction and evolution reaction. In the present work co-doped carbon materials have been developed from polymeric precursors with abundant active sites to achieve bifunctional activity. A 3-dimensional microporous nitrogen–carbon (NC) and co-doped nitrogen–sulfur–carbon (NSC) and nitrogen–phosphorus–carbon (NPC) were synthesized using poly(2,5-benzimidazole) as an N containing precursor. The obtained sheet like structure shows outstanding ORR and OER performance in alkaline systems with excellent stability compared to Pt/C catalyst. The doped heteroatom in the carbon is expected to have redistributed the charge around heteroatom dopants lowering the ORR potential and modifying the oxygen chemisorption mode thereby weakening the O–O bonding and improving the ORR activity and overall catalytic performance. The bifunctional activity (ΔE = E_j=10 − E_1/2) of an air electrode for NPC, NSC, NC and Pt/C is 0.82 V, 0.87 V, 1.06 V and 1.03 V respectively, and the NPC value is smaller than most of the reported metal and non-metal based electrocatalysts. The ORR (from onset potential) and OER (10 mA cm⁻²) overpotential for NPC, NSC, and NC is (290 mV, 410 mV), (310 mV, 450 mV) and (340 mV, 600 mV) respectively. In the prepared catalyst the NPC exhibited higher ORR and OER activity (NPC > NSC > NC). The doping of P in NPC is found to have a great influence on the microstructure and therefore on the ORR and OER activity.

Metal free bifunctional catalysts based on co-doped carbon materials synthesized from polymeric precursors via a simple pyrolysis route with high cyclic stability and low polarization for Zn–air batteries.

Ultrathin 2D Mesoporous TiO2 /rGO Heterostructure for High-Performance Lithium Storage

Lithium-ion batteries (LIBs) have been widely applied and studied as an effective energy supplement for a variety of electronic devices. Titanium dioxide (TiO₂ ), with a high theoretical capacity (335 mAh g^-1 ) and low volume expansion ratio upon lithiation, has been considered as one of the most promising anode materials for LIBs. However, the application of TiO₂ is hindered by its low electrical conductivity and slow ionic diffusion rate. Herein, a 2D ultrathin mesoporous TiO₂ /reduced graphene (rGO) heterostructure is fabricated via a layer-by-layer assembly process. The synergistic effect of ultrathin mesoporous TiO₂ and the rGO nanosheets significantly enhances the ionic diffusion and electron conductivity of the composite. The introduced 2D mesoporous heterostructure delivers a significantly improved capacity of 350 mAh g^-1 at a current density of 200 mA g^-1 and excellent cycling stability, with a capacity of 245 mAh g^-1 maintained over 1000 cycles at a high current density of 1 A g^-1 . The in situ transmission electron microscopy analysis indicates that the volume of the as-prepared 2D heterostructures changes slightly upon the insertion and extraction of Li⁺ , thus contributing to the enhanced long-cycle performance.

Bullet-like microstructured nickel ammonium phosphate/graphene foam composite as positive electrode for asymmetric supercapacitors

Unique microstructured nickel ammonium phosphate Ni(NH4)2(PO3)4·4H2O and Ni(NH4)2(PO3)4·4H2O/GF composite were successfully synthesized through the hydrothermal method with different graphene foam (GF) mass loading of 30, 60 and 90 mg as a positive electrode for asymmetric supercapacitors. The crystal structure, vibrational mode, texture and morphology of the samples were studied with X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and scanning electron microscopy (SEM). The prepared materials were tested in both 3-and 2-electrode measurements using 6 M KOH electrolyte. The composite material Ni(NH4)2(PO3)4·4H2O/60 mg exhibited a remarkable gravimetric capacity of 52 mA h g-1, higher than the 34 mA h g-1 obtained for the Ni(NH4)2(PO3)4·4H2O pristine sample, both at 0.5 A g-1. For the fabrication of the asymmetric device, activated carbon from pepper seed (ppAC) was used as a negative electrode while Ni(NH4)2(PO3)4·4H2O/60 mg GF was adopted as the positive electrode. The Ni(NH4)2(PO3)4·4H2O/60 mg GF//ppAC asymmetric device delivered a specific energy of 52 Wh kg-1 with an equivalent specific power of 861 W kg-1 at 1.0 A g-1 within a potential range of 0.0-1.5 V. Moreover, the asymmetric device displayed a capacity retention of about 76% for over 10 000 cycles at a high specific current of 10.0 A g-1.

Sucrose-templated interconnected meso/macro-porous 2D symmetric graphitic carbon networks as supports for α-Fe2O3 towards improved supercapacitive behavior

In this study, ultrahigh electrochemical performance for interconnected meso/macro-porous 2D C@α-Fe₂O₃ synthesized via sucrose-assisted microwave combustion is demonstrated. Hematite (α-Fe₂O₃) synthesized via the same approach gave an encouraging electrochemical performance close to its theoretical value, justifying its consideration as a potential supercapacitor electrode material; nonetheless, its specific capacitance was still low. The pore size distribution as well as the specific surface of bare α-Fe₂O₃ improved from 145 m² g⁻¹ to 297.3 m² g⁻¹ after it was coated with sucrose, which was endowed with ordered symmetric single-layer graphene (2D graphene). Accordingly, the optimized hematite material (2D C@α-Fe₂O₃) showed a specific capacitance of 1876.7 F g⁻¹ at a current density of 1 A g⁻¹ and capacity retention of 95.9% after 4000 cycles. Moreover, the material exhibited an ultrahigh energy density of 93.8 W h kg⁻¹ at a power density of 150 W kg⁻¹. The synergistic effect created by carbon-coating α-Fe₂O₃ resulted in modest electrochemical performance owing to extremely low charge transfer resistance at the electrode–electrolyte interface with many active sites for ionic reactions and efficient diffusion process. This 2D C@α-Fe₂O₃ electrode material has the capacity to develop into a cost-effective and stable electrode for future high-energy-capacity supercapacitors.

In this study, ultrahigh electrochemical performance for interconnected meso/macro-porous 2D C@α-Fe₂O₃ synthesized via sucrose-assisted microwave combustion is demonstrated.

Hierarchical N-Doped Porous Carbons for Zn-Air Batteries and Supercapacitors

Nitrogen-doped carbon materials with a large specific surface area, high conductivity, and adjustable microstructures have many prospects for energy-related applications. This is especially true for N-doped nanocarbons used in the electrocatalytic oxygen reduction reaction (ORR) and supercapacitors. Here, we report a low-cost, environmentally friendly, large-scale mechanochemical method of preparing N-doped porous carbons (NPCs) with hierarchical micro-mesopores and a large surface area via ball-milling polymerization followed by pyrolysis. The optimized NPC prepared at 1000 °C (NPC-1000) offers excellent ORR activity with an onset potential (Eonset) and half-wave potential (E1/2) of 0.9 and 0.82 V, respectively (vs. a reversible hydrogen electrode), which are only approximately 30 mV lower than that of Pt/C. The rechargeable Zn-air battery assembled using NPC-1000 and the NiFe-layered double hydroxide as bifunctional ORR and oxygen evolution reaction electrodes offered superior cycling stability and comparable discharge performance to RuO2 and Pt/C. Moreover, the supercapacitor electrode equipped with NPC prepared at 800 °C exhibited a high specific capacity (431 F g-1 at 10 mV s-1), outstanding rate, performance, and excellent cycling stability in an aqueous 6-M KOH solution. This work demonstrates the potential of the mechanochemical preparation method of porous carbons, which are important for energy conversion and storage.

Glutathione-adaptive peptide amphiphile vesicles rationally designed using positionable disulfide-bridges for effective drug transport

The drug loading/releasing capability of GSH-responsive nanovesicles self-assembled from peptide amphiphiles was controlled by varying the location and number of disulfide-linkages in the peptide for the selective drug-release into tumor cells.

Diaminopyrene modified reduced graphene oxide as a novel electrode material for excellent performance supercapacitors

Schematic illustration of the facile synthesis process of DAPrGOs nanocomposites, Ragone plots and the superior cyclic stability of the assembled DAPrGO1//DAPrGO1 SSS.

3D hierarchical rose-like Ni2P@rGO assembled from interconnected nanoflakes as anode for lithium ion batteries

In recent years, anode materials of transition metal phosphates (TMPs) for lithium ion batteries have drawn a vast amount of attention, due to their high theoretical capacity and comparatively low intercalation potentials vs. Li/Li⁺.

Three-dimensional ordered macroporous ZIF-8 nanoparticle-derived nitrogen-doped hierarchical porous carbons for high-performance lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have attracted considerable attention due to their ultra-high specific capacity and energy density.

Nitrogen-doped hollow carbon spheres with tunable shell thickness for high-performance supercapacitors

Nitrogen-doped hollow carbon spheres (NHCSs) are well prepared by using Cu₂O microspheres as a hard template and 3-aminophenol formaldehyde resin polymer as carbon and nitrogen precursors. The thickness of the carbon shell can be easily controlled in the range of 15–84 nm by simply adjusting the weight ratios of the precursors to Cu₂O microspheres, and the Cu₂O templates can also be further reused. Physicochemical characterization demonstrates that the obtained NHCSs possess a well-developed hollow spherical structure, thin carbon shell and high nitrogen doping content. Due to these characteristics, when further utilized as electrodes for supercapacitors, the NHCSs with the carbon shell thickness of 15 nm show a high capacitance of 263.6 F g⁻¹ at 0.5 A g⁻¹, an outstanding rate performance of 122 F g⁻¹ at 20 A g⁻¹ and an excellent long-term cycling stability with only 9.8% loss after 1000 cycles at 5 A g⁻¹ in 6 M KOH aqueous electrolyte. This finding may push forward the development of carbon materials, exhibiting huge potential for electrochemical energy storage applications.

Nitrogen-doped hollow carbon spheres (NHCSs) are well prepared by using Cu₂O microspheres as a hard template and 3-aminophenol formaldehyde resin polymer as carbon and nitrogen precursors.

CuCo2O4 nanoneedle array with high stability for high performance asymmetric supercapacitors

Cycling performance is very important to device application. Herein, a facile and controllable approach is proposed to synthesize high stability CuCo₂O₄ nanoneedle array on a conductive substrate. The electrode presents excellent performances in a large specific capacitance up to 2.62 F cm⁻² (1747 F g⁻¹) at 1 mV s⁻¹ and remarkable electrochemical stability, retaining 164% even over 70 000 cycles. In addition, the asymmetric supercapacitor assembled with the optimized CuCo₂O₄ nanoneedle array (cathode) and active carbon (anode), which exhibits superior specific capacity (146 F g⁻¹), energy density (57 W h kg⁻¹), and cycling stability (retention of 83.9% after 10 000 cycles). These outstanding performances are mainly ascribed to the ordered binder-free nanoneedle array architecture and holds great potential for the new-generation energy storage devices.

The CuCo₂O₄ nanoneedle array with enhanced electrochemical performance especially high stability is due to the hierarchical porosity framework with the high mesoporous nanoneedle array.

Enhanced capacitive properties of all-metal-oxide-nanoparticle-based asymmetric supercapacitors

The major problem of transition metal oxide (TMO)-based supercapacitors is their low specific energy (E_sp) due to the poor electrical conductivity of the TMO electrodes and narrow operating voltage window. To solve these limitations simultaneously, we propose asymmetric supercapacitors (ASCs) consisting of two composite TMO electrodes working in different potential ranges. Titanium dioxide (TiO₂) nanoparticle (NP)-incorporated iron oxide (Fe₂O₃) and manganese oxide (MnO₂) NPs were used as electrode materials covering the negative and positive potential window, respectively. The specific capacitance (C_sp) of this asymmetric TiO₂–Fe₂O₃‖TiO₂–MnO₂ supercapacitor is comparable to that of the symmetric TiO₂–MnO₂‖TiO₂–MnO₂ supercapacitor. However, the ASC can operate over a doubly extended voltage range, which resulted in a significant enhancement in the specific energy of the device. The E_sp value of the ASC at a specific power of 1000 W kg⁻¹ is 48.6 W h kg⁻¹, which is 34.1 and 8.1 times, respectively, larger than that of the two symmetric devices.

This study reports on an asymmetric supercapacitor consisting of two composite transition metal oxide (TiO₂–Fe₂O₃ and TiO₂–MnO₂) nanoparticles-based electrodes working in different potential ranges.

Dicarbonyl-tuned microstructures of hierarchical porous carbons derived from coal-tar pitch for supercapacitor electrodes

A simple and effective template-free method to prepare hierarchical porous carbons (HPCs) has been developed by using low-cost coal-tar pitch as a starting material, anhydrous aluminum chloride as the Friedel–Crafts catalyst, and oxalyl chloride as the cross-linking agent. By a simple controllable Friedel–Crafts reaction, diketone-functionalized coal-tar pitch as the hierarchical porous coal-tar pitch precursor was obtained via a one-step carbonization to provide a well-developed micro–mesoporous network. Nitrogen adsorption and desorption measurements showed that the surface area, pore volume, pore size and pore size distributions of the resulting carbon materials was dependent on the usage of the cross-linking agent. The as-fabricated HPCs have a large Brunauer–Emmett–Teller specific surface area of 1394.6 m² g⁻¹ and exhibit an excellent electrochemical performance with the highest specific capacitance of 317 F g⁻¹ at a current density of 1 A g⁻¹ in a three-electrode system. A symmetric supercapacitor was fabricated from HPC-DK-1.0 in a two-electrode system, which exhibits a high specific capacitance of 276 F g⁻¹ at a current density of 0.25 A g⁻¹, a high rate capability and an excellent cycling stability with a capacitance retention of 92.9% after 10 000 cycles. The one-step carbonization method that produced HPCs for electrical double-layer capacitors represents a new approach for high-performance energy storage.

The hierarchical porous carbons have an excellent cycling stability with a capacitance retention of 92.9% after 10 000 cycles.

Heteroatom-doped hollow carbon spheres made from polyaniline as an electrode material for supercapacitors

In this work, novel heteroatom-doped hollow carbon spheres (HHCSs) were prepared via the carbonization of polyaniline hollow spheres (PHSs), which were synthesized by one-pot polymerization. It was found that the carbonized PHSs at 700 °C exhibit high specific capacitance of 241 F g⁻¹ at a current density of 0.5 A g⁻¹ and excellent rate capability. The excellent electrochemical performance can be attributed to the heteroatom-doping and hollow carbon nanostructure of the HHCSs electrodes. Heteroatom groups in the HHCSs not only improve the wettability of the carbon surface, but also enhance the capacitance by addition of a pseudocapacitive redox process. Their unique structure provides a large specific surface area along with reduced diffusion lengths for both mass and charge transport.

In this work, novel heteroatom-doped hollow carbon spheres (HHCSs) were prepared via the carbonization of polyaniline hollow spheres (PHSs), which were synthesized by one-pot polymerization.

Nitrogen-doped hollow carbon spheres as chemical vapour sensors

The sensitivities of N-HCSs and annealed HCSs towards various analytes revealing a decrease in water sensitivity of the N-HCSs.

Hierarchical porous carbon derived from carboxylated coal-tar pitch for electrical double-layer capacitors

Hierarchical porous carbons have been synthesized using amphiphilic carboxylated coal-tar pitch as a precursor via a simple KOH activation process. Amphiphilic carboxylated coal-tar pitch has a high content of hydrophilic carboxyl groups that enable it to be easily wetted in KOH solution and that facilitate the activation process. In the present study, the effect of the activation agent to precursor ratio on the porosity and the specific surface area was studied by nitrogen adsorption–desorption. A maximum specific surface area of 2669.1 m² g⁻¹ was achieved with a KOH to carboxylated pitch ratio of three and this produced a structure with micropores/mesopores. Among the various hierarchical porous carbons, the sample prepared with an activation agent to precursor ratio of two exhibited the best electrochemical performance as an electrode for an electrical double-layer capacitor in a 6 M KOH electrolyte. The specific capacitance of the sample was 286 F g⁻¹ at a current density of 2 A g⁻¹ and it had a capacitance-retention ratio of 93.9%, even after 10 000 cycles. Thus, hierarchical porous carbons derived from amphiphilic-carboxylated coal-tar pitch represent a promising electrode material for electrical double-layer capacitors.

The specific capacitance of the HPC-2 electrode retention of 93.9% was obtained after 10 000 cycles, indicating good electrochemical stability.

Capacitive performance of vertically aligned reduced titania nanotubes coated with Mn2O3 by reverse pulse electrodeposition

In this study, a composite material, manganese oxide/reduced titania nanotubes (Mn2O3/R-TNTs), was synthesized through incorporation of Mn2O3 onto R-TNTs via the reverse pulse electrodeposition technique. The influence of pulse reverse duty cycles on the morphological, structural and electrochemical performance of the surface was studied by varying the applied duty cycle from 10% to 90% for 5 min total on-time at an alternate potential of -0.90 V (E on) and 0.00 V (E off). FESEM analysis revealed the uniform deposition of Mn2O3 on the circumference of the nanotubes. The amount of Mn2O3 loaded onto the R-TNTs increased as a higher duty cycle was applied. Cyclic voltammetry and galvanostatic charge-discharge tests were employed to elucidate the electrochemical properties of all the synthesized samples in 1 M KCl. The specific capacitance per unit area was greatly enhanced upon the incorporation of Mn2O3 onto R-TNTs, but showed a decrease as a high duty cycle was applied. This proved that low amounts of Mn2O3 loading enhanced the facilitation of the active ions for charge storage purposes. The optimized sample, Mn2O3/R-TNTs synthesized at 10% duty cycle, exhibited high specific capacitance of 18.32 mF cm-2 at a current density of 0.1 mA cm-2 obtained from constant current charge-discharge measurements. This revealed that the specific capacitance possessed by Mn2O3/R-TNTs synthesized at 10% duty cycle was 6 times higher than bare R-TNTs.

Oxygen functional groups improve the energy storage performances of graphene electrochemical supercapacitors

Graphene is a promising electrode material for supercapacitors due to its superior physical and chemical properties, but the influence of its oxygen functional groups on capacitive performance still remains somewhat uncertain. In this work, graphene sheets with different oxygen content have been prepared through thermal reduction in argon. Furthermore, oxidation and pore-forming treatment of graphene annealed at 800 °C are also performed to explore the important effect of oxygen functional groups. The effects of disorder degree, surface area and oxygen functional groups on the specific capacitance were explored systematically. The content and species of oxygen functional groups are found to be significant factors influencing the electrochemical supercapacitor performance of graphene electrodes. The specific capacitances of graphene annealed at 200, 400 and 800 °C are 201, 153 and 34 F g⁻¹, respectively. However, the specific capacitance of graphene reduced at 800 °C can be increased to 137 F g⁻¹ after nitric acid oxidation treatment, and is only 39 F g⁻¹ after pore forming on graphene surface, demonstrating that the oxygen functional groups can improve the capacitive performances of graphene electrochemical supercapacitors.

The content and species of oxygen functional groups are significant factors influencing the electrochemical supercapacitor performance of graphene electrodes.

Sustainable rose multiflora derived nitrogen/oxygen-enriched micro-/mesoporous carbon as a low-cost competitive electrode towards high-performance electrochemical supercapacitors

Cost-efficient carbonaceous materials have been utilized extensively for advanced electrochemical supercapacitors. However, modest gravimetric/volumetric capacitances are the insuperable bottleneck in their practical applications. Herein, we develop a simple yet scalable method to fabricate low-cost micro-/mesoporous N/O-enriched carbon (NOC-K) by using natural rose multiflora as a precursor with KOH activation. The biomass-derived NOC-K is endowed with a large surface area of ∼1646.7 m² g⁻¹, micro-/mesoporosity with ∼61.3% microporosity, high surface wettability, and a high content of N (∼1.2 at%)/O (∼26.7 at%) species. When evaluated as an electroactive material for supercapacitors, the NOC-K electrode (5 mg cm⁻²) yields large gravimetric/volumetric specific capacitances of ∼340.0 F g⁻¹ (∼238.0 F cm⁻³) at 0.5 A g⁻¹, and even ∼200.0 F g⁻¹ (∼140.0 F cm⁻³) at 5.0 A g⁻¹, a low capacitance decay of ∼4.2% after 8200 consecutive cycles, and a striking specific energy of ∼8.3 W h kg⁻¹ in aqueous KOH electrolyte, benefiting from its intrinsic structural and compositional superiorities. Moreover, a remarkable specific energy of ∼52.6 W h kg⁻¹ and ∼96.6% capacitance retention over 6500 cycles for the NOC-K based symmetric cell are obtained with the organic electrolyte. More promisingly, the competitive NOC-K demonstrates enormous potential towards advanced supercapacitors both with aqueous and organic electrolytes as a sustainable electrode candidate.

Hierarchical micro-/mesoporous N/O-enriched carbon was scalably fabricated, and exhibited high gravimetric/volumetric capacitances, a large energy density and long-term cycling stability for supercapacitors with aqueous and organic electrolytes.

Light and Strong Hierarchical Porous SiC Foam for Efficient Electromagnetic Interference Shielding and Thermal Insulation at Elevated Temperatures

A novel light but strong SiC foam with hierarchical porous architecture was fabricated by using dough as raw material via carbonization followed by carbothermal reduction with silicon source. A significant synergistic effect is achieved by embedding meso- and nanopores in a microsized porous skeleton, which endows the SiC foam with high-performance electromagnetic interference (EMI) shielding, thermal insulation, and mechanical properties. The microsized skeleton withstands high stress. The meso- and nanosized pores enhance multiple reflection of the incident electromagnetic waves and elongate the path of heat transfer. For the hierarchical porous SiC foam with 72.8% porosity, EMI shielding can be higher than 20 dB, and specific EMI effectiveness exceeds 24.8 dB·cm³·g^-1 at a frequency of 11 GHz at 25-600 °C, which is 3 times higher than that of dense SiC ceramic. The thermal conductivity reaches as low as 0.02 W·m^-1·K^-1, which is comparable to that of aerogel. The compressive strength is as high as 9.8 MPa. Given the chemical and high-temperature stability of SiC, the fabricated SiC foam is a promising candidate for modern aircraft and automobile applications.

Materials Design and System Construction for Conventional and New-Concept Supercapacitors

With the development of renewable energy and electrified transportation, electrochemical energy storage will be more urgent in the future. Supercapacitors have received extensive attention due to their high power density, fast charge and discharge rates, and long-term cycling stability. During past five years, supercapacitors have been boomed benefited from the development of nanostructured materials synthesis and the promoted innovation of devices construction. In this review, we have summarized the current state-of-the-art development on the fabrication of high-performance supercapacitors. From the electrode material perspective, a variety of materials have been explored for advanced electrode materials with smart material-design strategies such as carbonaceous materials, metal compounds and conducting polymers. Proper nanostructures are engineered to provide sufficient electroactive sites and enhance the kinetics of ion and electron transport. Besides, new-concept supercapacitors have been developed for practical application. Microsupercapacitors and fiber supercapacitors have been explored for portable and compact electronic devices. Subsequently, we have introduced Li-/Na-ion supercapacitors composed of battery-type electrodes and capacitor-type electrode. Integrated energy devices are also explored by incorporating supercapacitors with energy conversion systems for sustainable energy storage. In brief, this review provides a comprehensive summary of recent progress on electrode materials design and burgeoning devices constructions for high-performance supercapacitors.

Synthesis of a hierarchical nanoporous carbon material with controllable pore size and effective surface area for high-performance electrochemical capacitors

There is an excellent linear relationship between E-SSA and specific capacitance of HNC-IPNs as electrode materials for EDLCs.

A ternary composite with manganese dioxide nanorods and graphene nanoribbons embedded in a polyaniline matrix for high-performance supercapacitors

A new ternary composite of manganese dioxide (MnO₂), polyaniline (PANI) and graphene nanoribbons (GNRs) has been fabricated through a two-step polymerization process.

Template-free synthesis of nitrogen doped carbon materials from an organic ionic dye (murexide) for supercapacitor application

The present study describes a template-free single step carbonization route to prepare hierarchically structured nitrogen-doped carbon materials (NCMs) by using an organic ionic dye (OID), ammonium purpurate (murexide).

Agricultural waste-derived activated carbon for high performance lithium-ion capacitors

The optimized AC//LTO LIC is worth noting that our device outperformed most of the similar constructions concerning carbonaceous materials as cathode and LTO as anode and some other constructions.

An optimized 3D carbon matrix for high rate silicon anodes

A 3D porous carbon matrix with silicon particles embedded shows high rate performance in a lithium ion battery.

Hierarchical nitrogen-doped porous carbon derived from lecithin for high-performance supercapacitors

The development of renewable carbon sources for sustainable energy storage applications is of significance importance.

Optimization of Curcumin-Loaded PEG-PLGA Nanoparticles by GSH Functionalization: Investigation of the Internalization Pathway in Neuronal Cells

One major challenge in the field of nanotherapeutics is to increase the selective delivery of cargo to targeted cells. Using polylactic-co-glycolic acid (PLGA), we recently highlighted the importance of polymer composition in the biological fate of the nanodrug delivery systems. However, the route of internalization of polymeric nanoparticles (NPs) is another key component to consider in the elaboration of modern and targeted devices. For that purpose, herein, we effectively synthesized and characterized glutathione-functionalized PLGA-nanoparticles (GSH-NPs) loaded with curcumin (GSH-NPs-Cur), using thiol-maleimide click reaction and determined their physicochemical properties. We found that GSH functionalization did not affect the drug loading efficiency (DLE), the size, the polydispersity index (PDI), the zeta potential, the release profile, and the stability of the formulation. While being nontoxic, the presence of GSH on the surface of the formulations exhibits a better neuroprotective property against acrolein. The neuronal internalization of GSH-NPs-Cur was higher than free curcumin. In order to track the intracellular localization of the formulations, we used a covalently attached rhodamine (PLGA-Rhod), into our GSH-functionalized matrix. We found that GSH-functionalized matrix could easily be taken up by neuronal cells. Furthermore, we found that GSH conjugation modifies the route of internalization enabling them to escape the uptake through macropinocytosis and therefore avoiding the lysosomal degradation. Taken together, GSH functionalization increases the uptake of formulations and modifies the route of internalization toward a safer pathway. This study shows that the choice of ideal ligand to develop NPs-targeting devices is a crucial step when designing innovative strategy for neuronal cells delivery.

Electrochemical catalytic activity study of nitrogen-containing hierarchically porous carbon and its application in dye-sensitized solar cells

Nitrogen-containing hierarchically porous carbon is derived by carbonizing and activating polypyrrole nanostructure (APNP) using a template-free synthesis method and is demonstrated to be an efficient counter electrode (CE) in dye-sensitized solar cells (DSSCs).