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Pre-oxidation treatment is a key process to produce carbon anodes for sodium ion batteries from pitch because it governs the orientation of carbon layers during subsequent carbonization. However, the relationship between the oxygen functionalities in the oxidized pitch and the evolution of carbon structure during carbonization remains unclear. Herein, cross-linked asphalts with differentiated oxygen functionalities such as C–O and C(O)–O (ester group and anhydride), are synthesized to explore their effects on the evolution of carbon structure. The planar cross-linked structures constructed by thermally stable C–O fail to prevent the sliding of carbon layer, leading the formation of short-range order carbon structures with lager lateral size. In contrast, the three-dimensional cross-linked structures constructed by C(O)–O effectively prevent the rearrangement of asphalt at early pyrolysis. Owing to the gas generated by C(O)–O removal during subsequent carbonization, the as-formed more disorder carbon structures with small microcrystalline sizes can generate more closed pores and ultra-micropores, which enhances the low-voltage plateau capacity from 96.06 to 132.2 mAh g−1. The insights for the differentiated oxygen functionalities in regulating the carbon structural conversion pave the way for further development of pitch-based hard carbons with higher performance and their practical applications in SIBs. The main oxygen functionalities in the cross-linked asphalt, including C–O and C(O)–O, govern the microstructural formation of the asphalt-based hard carbon during carbonization, which further optimize the low-voltage plateau capacity for SIBs. [Display omitted] • Distinguished oxygen functionalities are introduced into the cross-linked asphalt at specific temperature and time. • The effects of different oxygen functionalities' evolution on hard carbon structure formation are proposed. • C(O)–O (ester group and anhydride) contributes the formation of closed pores and ultra-microporous pores in hard carbon. [ABSTRACT FROM AUTHOR]

Despite great progress in sodium-ion battery, exploiting carbonaceous anodes incorporating large capacity, high rate performance and long-term cycling stability is still a big challenge. In this work, novel heterostructured, hollow hard−soft carbon spheres are designed by mesopore confined carbonization. The results show that the confined carbonization makes the carbon layers spontaneously arrange in different levels, resulting in the formation of nanometer-scale, interwoven hard and soft carbon domains. Moreover, the unique composite carbon layers provide a flexible and breathable shell capable of maintaining nanostructure during long-term repeated charge/discharge processes. As such, the hard−soft carbon heterostructure is able to deliver a capacity >240 mA h g−1 under a current density of 1 A g−1. Even with an ultralarge current density of 30 A g−1, the capacity remains 104 mA h g−1, demonstrating a very short Na output time of 12.5 s. Moreover, the hard−soft carbon heterostructure shows no dramatic capacity loss during a long-term repeated charge/discharge tests over 10,000 cycles, showing a very low capacity loss rate of 0.0026% per cycle. As far as is known, such high-rate capability and outstanding cycling durability has been rarely achieved before. [Display omitted] • Heterostructured, hollow hard−soft carbon spheres are designed. • The heterostructured carbon has flexible skeleton with superior structural stability. • The obtained carbon can withstand an ultrafast Na storage of 30 A g−1. • Very low capacity loss rate of 0.0026% per cycle during long-term cycling test over 10,000 cycles. [ABSTRACT FROM AUTHOR]

The specific surface area (SSA) and pore structure are two critical factors that determine the energy storage performance of carbon-based supercapacitors. However, for biobased carbon electrodes, it is difficult to simultaneously control the pore structures and achieve high SSA. Herein, highly porous carbons (HPCs) with ultrahigh SSA and controllable pore structures are produced through hydrogel-controlled carbonization and activation process for glucose. Polyacrylamide (PAM) is used as the pore-forming agent, and pore structures can be regulated by controlling the content of PAM. The highest SSA of the HPCs reaches 3381 m2 g−1 with a 60% PAM content. Compared with the sample without PAM, the specific capacitance of HPCs-60 shows a 63% increase, reaching 441 F g−1 at a current density of 0.25 A g−1. Moreover, a KOH/PVA symmetric supercapacitor assembled from HPCs-60 not only exhibits an excellent energy density (10.9 Wh kg−1 at a power density of 125 W kg−1) but also has high cycling stability (∼10% loss over 20,000 cycles) and good flexibility. The as-prepared supercapacitors can provide stable power supplies for multiple electronic devices, indicating that the HPCs have enormous potential for use in high-performance electrochemical energy storage devices. Highly porous carbons with ultrahigh specific surface areas and controllable pore structures were obtained by hydrogel-controlled carbonization and activation of glucose. [Display omitted] [ABSTRACT FROM AUTHOR]

The controlled pyrolysis of polyetherimide (PEI) and similar polymers can be used to obtain rigid and nanoporous carbonaceous materials, applied as carbon molecular sieve membranes for gas separation, among other purposes. Most of the knowledge regarding the control of their final properties according to the pyrolysis conditions, as reported in the literature, is empirical. In this work, we present results of a comprehensive analysis of reactive molecular dynamics simulations to investigate the dependence of the temperature, initial density and processing time on the morphological, compositional and structural features of carbonaceous materials formed upon PEI pyrolysis, as well as to identify the most common reaction mechanisms responsible for the transformations in the material. Our results show how the aforementioned variables affects significantly the structure and composition of the material, and emphasize the importance of controlling processing conditions toward optimized properties for practical applications. Our findings agree with experimental results from the literature, helping to understand them from a most fundamental point of view and improving the knowledge on how to control the underlying features of PEI-based pyrolyzed materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Plants possess the natural organic composite frameworks and the desirable micro-architecture, which are one kind of the promising precursors of porous carbons. In this work, corn stalks are studied as carbon precursors for the efficient utilization of their sponge-like tissue. Unlike other reported works, this study focuses on the carbonization mechanism of corn stalks and the inherited process from the organic composite tissues to carbon frameworks. After three carbonization stages, the cellular-like porous biocarbons with the replicated biological structures were generated from corn stalks. It is found that the lignin-networks wrapped on cellulose and hemicellulose will become into the main composition of the carbon-skeletons. The gas-phase products derived from carbohydrates promoted the lignin carbonization into porous carbon frameworks, which inherit the cellular structure and the anisotropy of plant tissues. Based on our discovery, the ruthenium nanoparticles are prepared by using the spontaneous capillary action and the steric hindrance of plant tissues. Due to the high-dispersion active particles and the accelerated mass transfer, the in-situ prepared composite electrocatalysts exhibit high performance towards the hydrogen evolution reaction. This study provides a new idea to establish an environmentally sustainable solution of agricultural waste and the utilization of plants natural structures for high-performance applications. [Display omitted] • Cellular-like porous carbons were replicated from corn stalk inners. • The wrapped lignin is the main carbon source of biocarbons. • The interactions in the main ingredients play an important role in carbonization. • Ultrafine Ru nanoparticles were in-situ prepared on carbons. • The anisotropic properties and HER performance are also inherited from bio tissues. [ABSTRACT FROM AUTHOR]

Low-cost walnut shell-based carbons with high microporosity were prepared by simple one-step carbonization with chemical activation using KOH, exhibiting the promising potential to be a very good CO 2 and H 2 adsorbent. The physicochemical properties of the obtained carbons were characterized by N 2 and CO 2 adsorption isotherms, X-ray powder diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and elemental analysis. The activated carbon AC-800 was characterized by a highly developed specific surface area of 1868 cm2/g and a high micropore content of 0.94 cm3/g. It highly exhibited CO 2 uptake in 1 bar was up to 9.54, 5.17, 4.33 mmol/g for 0, 25 and 40 °C, respectively. In addition, the H 2 storage capacity was 3.15 mmol/g at 40 bars. Significantly, confirmed an exceptionally high dependency of CO 2 and H 2 uptake vs micropores structure of activated carbon. AC-800 also shows good selectivity for CO 2 /N 2 and fast adsorption kinetics that be easily regenerated with superior cyclic stability after multiple cycles The experimental isotherm data of activated carbon produced from walnut shells were analyzed using Langmuir, Freundlich, Temkin, Sips, and Toth isotherm equations. The fitting details showed that the multitemperature Toth equation is a powerful tool to mathematically represent CO 2 and H 2 isotherms on activated carbon. The easy way of preparation and high capture abilities endow this kind of activated carbon attractive as a promising adsorbent for CO 2 and H 2 storage. [Display omitted] • Walnut shells have been used successfully to synthesize AC. • AC display an appropriate micropore structure to achieve high H 2 and CO 2 adsorption capacity. • The mechanism of CO 2 and H 2 adsorption has been explained. • AC-800 had high CO 2 /N 2 adsorption selectivity and stability. • Sample AC-800 display great potential for low-temperature H 2 storage. [ABSTRACT FROM AUTHOR]

In this study, the multi-element doped carbon nanospheres with core-shell structure (N,P,S-PCNs) have been successfully synthesized through the carbonization of hyper-cross-linked polystyrene nanospheres (HPSs) encapsulated with poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS). The phosphonitrilic chloride trimer can in-situ assemble on HPSs surface, forming a poly(phosphonitrilic chloride trimer) film via sulfonyldiphenol as cross-linking agent to obtain HPSs@PZS. Subsequently, the HPSs@PZS undergoes high-temperature calcination under N 2 atmosphere, and PZS with a well-preserved encapsulation capability efficiently incorporated N, P and S into carbon nanospheres to gain multi-element (N,P,S) co-doped carbon nanospheres (N,P,S-PCNs) with core-shell structure. The prepared N,P,S-PCNs exhibit exceptional dispersibility and stability as lubricant additives, effectively mitigating friction (reduced to 0.106) and wear (decreased by 84.0 %). The lubrication performance of N,P,S-PCNs is exceptional due to the nanospheres' remarkable ability to enter the gaps between friction pairs and form a deposition film on the surfaces. Moreover, the nanospheres can undergo a chemical reaction with the matrix surface, resulting in the formation of a chemical protective film. The composite protective film (deposition film and chemical protective film) significantly enhances the lubricants' ability to reduce friction and resist wear. N,P,S-PCNs, as nano-additives, can effectively enhance the anti-friction (0.106) and anti-wear (84.0 %) performance of 500SN under the protective film effects (deposition film and friction chemical protective film). [Display omitted] • PZS formed a coating on the surface of the HPSs. • Carbonization of HPSs@PZS incorporates N, P and S into carbon nanospheres. • N,P,S-PCNs as additives mitigate friction (0.106) and wear (84.0 %). • The protective friction film (90–100 nm) is formed on the steel matrix. [ABSTRACT FROM AUTHOR]

Hard carbon (HC) stands out as a promising anode material for sodium storage due to its unique structure. However, the pore structure regulation of HC still poses a significant challenge. Herein, we propose a combined method of hydrothermal pretreatment, freeze-drying, and high-temperature carbonization to regulate the pore structure of HC. During the hydrothermal processes, the assembly of graphene oxide (GO) with starch facilitates the formation of open pores, which are subsequently transformed into closed pores during high-temperature carbonization. Impressively, a hard carbon with a reversible capacity of 434 mA h g −1 at 30 mA g −1 has been prepared through the structure regulation. Compared to the sample without structural regulation, it demonstrates a remarkable increase of 184.21 mA h g−1, with an enhancement rate of 73.80 %. Simultaneously, the skeletal structure of GO serves as a conductive network and framework support, enabling favorable rate performance and excellent cycling stability. Furthermore, the sodium storage mechanism is deduced as "adsorption -- intercalation -- pore filling". Overall, this study can offer valuable insights into pore structure regulation for anode materials and shed light on sodium storage mechanisms. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper introduces contorted hexabenzocoronene (c-HBC) derivatives as a potential universal precursor for use in synthesis of sp2-crystalline carbon materials that have dimensionalities ranging from 1-D to 3-D. Carbon products with different dimensions and high crystallinity were synthesized by controlling the assembly dimensions and intermolecular interactions of c-HBC derivatives, which are largely affected by the edge element and the deposition conditions. Further control of crystallinity was achieved by involving copper vapor; the effect is shown to be limited by the thickness of the assembled c-HBC layer. Study of the carbonization of c-HBC allowed development of an effective strategy to grow graphene-like structure on arbitrary substrates. This ability is expected to be a foundation for designed synthesis of graphitic carbons that have optimum morphology and dimensions for targeted applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Despite extensive studies on structural changes during the carbonization process of pitch-derived fibers, an accurate description of the transformation from liquid crystalline domains into carbon crystallites is still limited to a few depictions based on common analytical tools for carbon fibers. We employed small-angle X-ray scattering (SAXS) with model fits for the unification of such disparate measures. The carbonization process below 1200 °C is divided into three sequential regimes: Regime I - disruption of stacked polyaromatic mesogens with fluctuations in elasticity from 300 to 600 °C; Regime II - full-scale transformation with enhancement in orientation from 600 to 800 °C; and Regime III - development of semi-crystalline carbon structures with elongation of microvoids from 800 to 1200 °C. By examining the viscoelastic properties of pitch-derived fibers during heat treatment below 600 °C (Regime I), we found that the maximum softness of the pitch-derived fibers is achieved at 500 °C. This is due to the decrease in crosslink density between stacking structures, indicating that the crosslink density below 600 °C is a significant contributor to the formation of carbon crystallites. [Display omitted] • The carbonization of pitch fibers below 1200 °C is divided into three regimes. • Microstructural change is depicted with domains, crystalline carbons and microvoids. • The transformation of domains into carbon crystallites occurs from 600 to 800 °C. • SAXS is employed for the unification of common analytical tools for carbon fibers. • Maximum softness of the pitch-derived fibers is achieved at 500 °C. [ABSTRACT FROM AUTHOR]

High surface area porous carbons derived from sustainable biomass wastes are excellent functional materials for energy storage and gas sorption applications. Tasmanian Blue Gum (TBG) tree bark is selected as the raw material for preparing activated porous carbon (AC), using a simple KOH activation and carbonization method. The as-prepared AC-TBG sample possesses a hierarchically connected mesoporous structure having a surface area of 971 m2 g−1 with an average pore size of 2.2 nm. AC-TBG exhibits high electrochemical storage capacity as fabricated symmetric supercapacitor, with excellent specific capacitances of 212 F g−1 at 1 A g−1 current density retaining 90% of its capacitance after 5000 cycles. An outstanding maximum power density of 4.9 kW kg−1 was obtained for the EDLC in 1 M KOH at a maximum energy density of 18.84 Wh kg−1, which is among the highest values reported in this class of materials. Furthermore, exploiting the multiscale porosity and oxygen/hydroxyl functionalities on the surface, AC-TBG was deployed for CO 2 capture from concentrated source as well as dilute 4% CO 2 simulated flue stream. AC-TBG showed an excellent uptake of 4.5 mmol/g of CO 2 at 1 bar and 0 °C for pure CO 2 and a working capacity of 1.6 mmol/g at 40 °C in 4% CO 2. This work provides a simple, and feasible strategy for converting sustainable waste biomass to value-added activated carbon with potential applications in high-performance energy storage and greenhouse gas capture. Activated carbon derived from bark of Tasmanian Blue Gum tree shows high CO 2 uptake capacity and excellent activity and cycle life as a fabricated symmetric supercapacitor. [Display omitted] [ABSTRACT FROM AUTHOR]

Highly dispersed fine FeNi nanoparticles (NPs) encapsulated within carbon nanofibers (FeNi@CNFs) have been fabricated through electrospinning followed by preoxidation and carbonization processes. The influences of FeNi content and filler loading on the electromagnetic (EM) and microwave absorption (MA) properties of the FeNi@CNFs/paraffin wax composites are studied in detail. Benefitting from the special hierarchical microstructure including zero-dimensional FeNi@graphitic carbon core-shell NPs, one-dimensional CNFs with short carbon nanotubes protrusions and three-dimensional conductive network, as well as the synergistic effect between small-sized magnetic FeNi NPs and lightweight dielectric CNFs, the as-prepared FeNi@CNFs samples exhibit excellent MA performances at the ultralow filler loading, in which the FeNi@CNFs-2 with a filling content of only 5 wt% possesses the strongest absorbing intensity and broadest effective frequency bandwidth primarily due to better balance between EM attenuation capability and impedance matching. The minimum reflection loss (RL) reaches −31.3 dB (more than 99.9% MA) at 16.3 GHz with a small thickness of 1.7 mm, and the maximum effective absorption bandwidth (RL < −10 dB) is up to 5.6 GHz (12.0–17.6 GHz) at 1.9 mm, which are superior to those of many previously reported magnetic carbon-based hybrid absorbers. Our results demonstrate that the proper incorporation of small-sized FeNi NPs into CNFs is an efficient and promising strategy to design lightweight and high-performance EM wave absorbers. [Display omitted] • 1D FeNi@CNFs were simply synthesized as high-performance microwave absorbers. • Impedance matching is improved by the introduction of small FeNi nanoparticles. • Optimal reflection loss can reach −31.3 dB at an ultralow filler loading of 5 wt%. • A maximum effective absorption bandwidth of 5.6 GHz can be achieved. [ABSTRACT FROM AUTHOR]

Mesophase-pitch-based carbon fibers (MPCFs) have excellent physical performance and are widely used in many cutting-edge fields. The regulation and control of temperature-dependent crystalline structure is very vital for improving their physical properties. Herein, a stretching technique was applied in the carbonization process to produce performance-improved MPCFs, through testing initially in laboratory batch experiments, and then upgrading into a pilot continuous production. For batch carbonization stretching on a bundle of fixed-length fibers, it is found that applying an appropriate tension helps improve their crystalline structure and physical properties. Compared to the "one-stage" constant tension, the "two-stage" variable tension is more conducive to the growth and orientation of graphite microcrystals in MPCFs and the improvement of their physical properties owing to the good match of tension and temperature. For continuous carbonization stretching on a bundle of long filaments, the optimal condition is under a suitable stretching ratio of 0.965 at 500–780 °C for 40 min. The tensile strength and modulus of the 3000°C-graphitized large-diameter MPCFs rise by ∼35% and ∼10%, respectively. The axial electrical resistivity (1.66 μΩ m) decreases by ∼25%, while the thermal conductivity (759.64 W/m K) increases by ∼33%. The effect of the continuous carbonization stretching has been verified to be well accordant with that of the batch in this work, which will pave the road for the wide application of hot-stretching in industrial production of high-performance MPCFs. [Display omitted] • Hot-stretching on pre-treated MPFs during carbonization process has been attained. • Applying an appropriate tension improves the structure and properties of MPCFs. • There exists a match of tension and temperature during stretching carbonization. • The effect of continuous carbonization stretching accords with that of the batch. • Microstructure evolution helps understand the improvement of physical properties. [ABSTRACT FROM AUTHOR]

The microstructure evolution of carbon fiber reinforced carbon aerogel-like matrix (C/CA) composites with carbonization temperature and its influence on their properties were investigated. The removal of residual organo-functional groups of the C/CA precursors is dominant when carbonized at 600–750 °C with a large volume shrinkage difference by 17–22% as compared to that at 1200 °C, while the rearrangement of novolac structures is dominant at 900–1200 °C with a slight volume shrinkage fluctuation of 6%. Resultantly, the amount of micropore first increases and then decreases, while the particle size experiences an opposite change. The microstructure correspondingly transforms from a completely amorphous state to a partially amorphous state with graphite crystallites in low-angle misorientation, and then with graphite-like entangling ribbons. Due to the reduced residual tensile stress and increased interfacial bonding, the resulting composites with a variable bulk density of 0.58–0.64 g cm−3 have much higher compressive strengths of 45.8–96.9 MPa than other reported carbon foams or aerogels with similar bulk densities. The increase of strength and modulus with carbonization temperature is mainly due to the smaller tensile stress, higher particle packing compactness, larger microcrystallite size and less residual organo-functional groups. The composites also present a relatively low thermal conductivity of 0.12–0.59 W m−1 K−1. The increase of thermal conductivity with temperature is related to the synergistic effect of reduced phonon scattering associated with smaller specific surface area, larger microcrystallite size and less organo-functional groups and improved phonon transfer associated with increased inter-particle contact area. [Display omitted] [ABSTRACT FROM AUTHOR]

Despite the numerous reports on carbon dots (CDs) synthesized from o-phenylenediamine (o-pd), the precise mechanism of fluorescence and formation processes of o-pd CDs have not been investigated. In this study, we purified o-pd CDs and obtained five compounds with yellow, green and blue emission. For the first time, two actual molecular fluorophores named 2,3-Diaminophenazine (DAP) and 2-Amino-3-hydroxyphenazine (AHP) were confirmed. More sophisticated investigations showed the DAP was dominant for the yellow emission, which confirmed molecule states in detail. More interestingly, DAP could form nanoparticles (NPs) with various sizes at different concentrations. In this regard, we propose that the formation processes of o-pd CDs were similar to those of carbonized polymer dots (CPDs), where DAP structures initially aggregated with themselves to form polymeric clusters, further carbonization of polymeric clusters endowed the polymer clusters with a preliminary core-shell structure. With the collapse of the shell and aromatization of the core, the CPDs like structure formed eventually. This study supplements those on the yellow-emissive fluorophores region and could be the potential reference for the preparation of CDs in a similar system. Two fluorophores corresponded to yellow emission named DAP and AHP were separated from o-pd CDs solution by HPLC for the first time, further investigation suggested these CDs formed from the aggregation of DAP. [Display omitted] • The chemical structure of DAP and AHP were confirmed for the first time. • The blank of yellow-emissive fluorophores was supplemented. • The existence of molecule state prepared by rigid precursor was first verified. • The formation of CDs was originated from DAP. • The multi-colors LEDs with high CRI were successfully prepared by fluorophores. [ABSTRACT FROM AUTHOR]

Pitch-based soft carbons, with tunable microstructure and low cost, hold great potential as anodes for potassium-ion batteries (PIBs). However, the sluggish storage kinetics and unsatisfying cycle life hinder their practical applications. In addition, low softening point pitch has been seldom used to fabricate carbon microspheres due to its thermoplasticity. Herein, P and O enriched pitch-based carbon microspheres were directly synthesized via coordinated emulsification and pre-oxidation, and followed carbonized with NaH 2 PO 2. This template-free method can avoid the coalescence of the coal tar pitch without extra post-stabilization. And NaH 2 PO 2 acts as a P doping source and generates modest mesopores. The prepared P and O enriched carbon microspheres manifest a high P content of 4.0 at%, expanded interlayer distance of 0.401 nm, and abundant reversible K+ storage sites. As a result, it delivers considerable discharge capacity of 352 mAh g−1, impressive rate capacity of 114 mAh g−1 at 5 A g−1, and long lifespan of 181 mAh g−1 at 1 A g−1 after 1000 cycles. The present work develops a new avenue for heteroatoms doped carbon microspheres to innovative potassium storage and beyond. P and O enriched carbon microspheres were directly synthesized via coordinated emulsification and pre-oxidation, and followed carbonized with NaH 2 PO 2 to yield expanded interlayer distance, abundant defects and reversible K+ storage sites. [Display omitted] • P/O enriched pitch-based carbon microspheres were successfully fabricated. • Simultaneous emulsification and oxidation prevent pitch from coalescence during carbonization. • The generated PH 3 steam creates abundant defects and acts as P source for the uniform doping. • The effect of microstructure on high-rate performance was systematically investigated. [ABSTRACT FROM AUTHOR]

With the increasing deterioration of the electromagnetic environment, it is important to develop new and efficient electromagnetic wave-absorbing materials. In this work, bilayer hollow HsGDY/NC nanotubes with controllable thickness are constructed by introducing high conductivity polydopamine (PDA) and hydrogen-substituted graphdiyne (HsGDY) followed by the etching and carbonization. Subsequently, the effects of the composition, coating order, and structural characteristics of nanotubes on the electromagnetic parameters are thoroughly investigated, thereby analyzing the microwave absorption mechanism. The impedance matching of HsGDY/NC is optimized by changing the thickness of NC layer, while utilizing unique multi-heterogeneous interfaces and hierarchical conductive structures that enhance the interface polarization and conductive loss. As a result, HsGDY@NC-3 displays the optimal absorbing performance with an effective absorption bandwidth (EAB) of 7.8 GHz (10.1–17.9 GHz) and a minimum reflection loss (RL min) of −47.18 dB at the filler content of only 11 %. This work broadens the application scopes of HsGDY and provides a novel insight into the design of lightweight, high-efficiency, and wide-frequency microwave absorbers, which is expected to be a potentially effective microwave-absorbing material. [Display omitted] • HsGDY/NC nanotubes with controllable thickness are prepared by the template method. • Summarizes the electromagnetic wave absorption mechanisms of hollow bilayer structures. • The nanotubes exhibit a L min of −47.18 dB and an EAB of 7.8 GHz. [ABSTRACT FROM AUTHOR]

Corn stalk was selected as a typical biomass, and the growth mechanism of coke microparticles was studied. The coke microparticles that formed from through the polymerization of aqueous organics during the hydrothermal carbonization (HTC) showed a considerable effect on the mass yield and physicochemical properties of the hydrochar. Results indicated that the average particle size of the coke microparticles rapidly increased to 6.25 μm within the initial 2 h of HTC. The lower C/O atomic ratio of the surface layer of the coke microparticles than that of the core, suggested that the core had a higher carbonization degree than the shell. On the basis of various measurements, the coke microparticles were inferred to have formed through the two stages of micronuclei formation and growth. Dissolved organics, including furfurals, furans, and phenols polymerized each other into aromatized macromolecules, and then formed solid-phase micronuclei. Subsequently, the oxygen containing groups of the micronuclei formed bonded with aqueous organic molecules, as a result, the micronuclei grew up into coke microparticles. Meanwhile, the carbonization degree of the coke microparticles was enhanced due to continuous intra- and inter-molecular dehydration and decarboxylation reactions occurred between hydroxyl and carboxyl groups. [Display omitted] [ABSTRACT FROM AUTHOR]

The radial microstructure development of polyacrylonitrile-based carbon fibers is traced during continuous carbonization from 400 to 1400 °C. Based on the changes in the microstructure and mechanical properties of the fibers, it is confirmed that they undergo four distinctive stages depending on the temperature: (1) further cyclization in a remained unstabilized structure (400–600 °C), (2) crosslinking by dehydrogenation (600–800 °C), (3) crosslinking by denitrogenation (1000–1200 °C), and (4) development of turbostratic structure (1200–1400 °C). A structural analysis of the surface, skin, and core regions reveals that the innermost structure (core) originates from a high degree of structural relaxation. In contrast, densification is dominated in the outermost structure (surface). Such a radial heterogeneity is attributed to gas evolution along the radial direction of the fibers during the high-temperature carbonization and fiber shrinkage. The tensile strength exhibits a strong relationship with the crystal sizes as compared to the degree of disorder and amorphous structures, indicating that the crystal growth by densification has a greater influence on the tensile properties than the structure relaxation. [Display omitted] [ABSTRACT FROM AUTHOR]

Lipid droplet (LD) is an organelle that stores lipids and plays crucial roles in many metabolic processes and diseases. However, developing a method for long-term tracing of LDs and monitoring LD movement remains a challenge. Here, by using a solvent-free carbonization method, we prepare a kind of boron- and nitrogen-codoped carbon dots (BNCDs) from 3-aminophenylboronic acid. The as-synthesized BNCDs have an average size of ∼6.9 nm, long-wavelength fluorescence emission, and excitation wavelength-independent fluorescence emission, and can realize wash-free LD imaging without the introduction of LD-targeting ligands. Besides, the BNCDs have the characteristics of good biocompatibility, simple preparation, and low cost. More importantly, the BNCDs can effectively track the dynamic changes of LDs (including lipophagy) in live animal cells. This work shows that the developed BNCDs can be used as an ideal probe for nondestructively visualizing LDs, which may have implications for the future studies on LDs-related metabolism and diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

The catalytic dehydrogenation of Ti 3 C 2 T x -MXene nanosheets induced by their surface terminating C-Ti-O group has attracted tremendous interests in the fabrication of unsaturated organics and carbon materials. Herein, the highly graphitic carbon quantum dots (CQDs) were synthesized by pyrolyzing cationic polystyrene (CPS) spheres which were wrapped by Ti 3 C 2 T x -MXene nanosheets. The morphological features and fluorescent properties of the as-prepared CQDs were characterized and the growth mechanism of CQDs was proposed. In this unique hybrid model, Ti 3 C 2 T x -MXene exhibited high efficiency in catalyzing dehydrogenation and carbonization of CPS to highly graphitic CQDs at a relatively low pyrolysis temperature of 410 °C. During the pyrolysis, Ti 3 C 2 T x -MXene shell acted as a closed barrier to retain the volatilization of degradation products of CPS and promote their diffusion into the MXene interlayers. Simultaneously, lots of CPS degradation products were adhered to the surface of Ti 3 C 2 T x -MXene nanosheets, where the dehydrogenation was carried out by the C-Ti-O catalytic active sites. Eventually, they were carbonized to highly graphitic CQDs with excellent photoluminescence behavior. This work provides a facile strategy to convert polystyrene matrix into graphitic carbon-based material, which helps to develop the catalytic carbonization mechanism of MXene/polymer nanocomposites. [Display omitted] [ABSTRACT FROM AUTHOR]

Petroleum asphaltenes, a by-product of crude oil extraction, are a promising feedstock for the development of high-value carbonaceous materials because of their high carbon content and aromaticity. In this work, we have studied the efficacy of low-value petroleum asphaltenes as raw materials in producing carbon fibers. We present a facile, yet effective, method to produce carbon fibers without the need of expensive pre-treatment processing. To do this, extensive physicochemical characterizations were carried out to evaluate asphaltene properties throughout the entire process. Continuous spinning of green fibers with different diameters (∼10–200 μm) was optimized according to the rheological characteristics of asphaltenes. We originally developed a multi-step stabilization process to cross-link the asphaltene-derived green fibers. This was followed by carbonization of the fibers resulting in fibers with mechanical strength of ∼400 MPa and Young's modulus of ∼70 GPa. These are relatively high values obtained without any pretreatment or high temperature carbonization/graphitization. This study presents a previously unexplored avenue to develop low-cost carbon fibers from low-value petroleum asphaltenes. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon fibers (CFs) have been considered as a next-generation material in high-performance applications such as aerospace, defense, sporting goods, wind energy, automobiles, electronics, and civil engineering industries due to their superior mechanical properties including high tensile strength and modulus and characteristics such as low density, good corrosion and low impact resistance, low coefficient of thermal expansion, and high electric conductivity. In this paper, we introduced the brief overview of the most widely produced and used polyacrylonitrile(PAN)-based CFs. In particular, the studies on developing high performance CFs by theoretical and experimental approaches were presented. Theoretical tensile strength of CFs can be ideally up to 100 GPa with the perfectly developed graphitic structure and its orientation along fiber direction. However, commercially available CFs reveal only tensile strength of 7 GPa because of the existing defects, misordered carbon crystals, and turbostratic structure. Those originate from manufacturing processes such as spinning, stabilization, and carbonization, which generate significant morphological and structural defects in both exterior and interior of CFs. The review covered the research on parameters related with the tensile properties and optimizing processes to increase the tensile strength of PAN-based CFs. [Display omitted] [ABSTRACT FROM AUTHOR]

Zinc-ion capacitors (ZICs) are newly emerged hybrid devices consisting of battery-type anodes and capacitive-type cathodes, which are expected to meet high energy-power demands. The performance of ZICs is usually limited by the poor performance of porous carbon cathodes. In this work, heteroatom doped, hierarchically porous carbons were developed using a straightforward and scalable one-step method. The specific surface areas and pore size distributions could be tailored by adjusting the precursor ratio and their effects on the electrochemical performance were investigated. The fabricated ZICs showed the highest capacity of 168.4 mAh g−1 with an energy density of 131.9 Wh kg−1 at 0.5 A g−1. The highest power density of 30.8 kW kg−1 could be achieved at 40 A g−1, allowing a fast complete discharging of a ZIC device in 6.6 s. Furthermore, the cycling stability of the device was investigated, registering nearly 100% capacity retention and almost 100% Coulombic efficiency after 12,000 cycles at 10 A g−1. The morphology and impedance tests measured at different charge and discharge conditions shed some light on the mechanism of the hybrid capacitive behavior. The proposed carbon cathodes offer great potential for ZICs in energy storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The π-conjugated domain, which is one of frequently-suggested fluorescence origin of carbon dots (CDs), can also act as fluorescence quenching origin in aggregated state. This dual role of the π-conjugated domain in CDs offers a challenge to prediction of photoluminescence (PL) characteristics in solid-state. Here, we focus on the effect of π-conjugated domain on the PL phenomenon for different interparticle separation using three types of CDs with different degree of carbonization. The degree of carbonization was controlled by selecting three alcoholic solvent species for solvothermal reaction, which can influence carbonization of CDs. In dilute dispersion, CDs from three different solvents possessed two emissive centers originated from surface- and core-state with different relative intensities depending on the degree of carbonization. With the increase in concentration of CDs, the higher contents of π-conjugated domain changed the dominant PL center from surface- to core-state due to the greater reduction of surface-derived emission. In aggregated state, the emission from surface-state was totally suppressed, and the π-conjugated domain contents influenced the emission efficiency of core-state. Based on PL decay results, we proposed the PL mechanism of the CDs for different interparticle separation, which would extend the boundary in the interpretation of PL properties of CDs. [Display omitted] • Content of π-domain in carbon dots (CDs) was regulated by changing solvent for the reaction. • In dilute dispersion, π-conjugated domain in the CDs acted as emissive origin. • In concentrated dispersion and solid-state, π-domain accelerated fluorescence quenching. [ABSTRACT FROM AUTHOR]

N/S-doped carbon materials hold great promise for the oxygen reduction reaction (ORR). Construction of uniform doping with desirable configurations and engineering of pore structure are essential to boost their performance. Herein, a single-precursor design and a solvent-free nanocasting approach are demonstrated to synthesize N/S/O-doped ordered mesoporous carbons (N/S/O-OMCs). The precursor cysteine (Cys) enables in-situ multiple doping. The special pyrolytic behavior of Cys confined in the ordered mesoporous silica (SBA-15) template enables efficient carbonization and structuration. The N/S/O-OMCs possess high surface areas (756–1339 m2/g), large pore volumes, trimodal pores (∼1.6, 4.6 and 7–100 nm), and high N/S/O contents. The influences of temperature and Cys/template mass ratio on the physicochemical properties of the N/S/O-OMCs are clarified. The N/S/O-OMCs are promising for ORR. The optimized sample shows high performance with high onset and half-wave potentials (0.95 and 0.87 V), a high limiting current density (5.9 mA/cm2), a high stability and excellent methanol tolerance. The correlations between the ORR performance and the physicochemical properties are elucidated. The high ORR performance of the optimized sample is attributed to its N/S/O doping with balanced graphitic-, pyridinic- and pyrrolic-N proportions and desirable C–S–C configuration, low charge transfer resistance, and hierarchical pore structure. [Display omitted] • A single-precursor design and a solvent-free nanocasting method for N/S/O-doped ordered mesoporous carbons. • Cysteine for in-situ multiple doping and confined pyrolysis for effective carbonization and structuration. • High ORR performance with high onset/half-wave potentials, high stability and excellent methanol tolerance. • Elucidated key influencing factors on physicochemical properties and ORR performance. • Desirable N/S configurations, low charge transfer resistance, and hierarchical pores determine the high ORR performance. [ABSTRACT FROM AUTHOR]

Biomass-based materials usually evolve well-developed and unique structures for the transportation of water and nutrition to their pivotal organs. These natural intricate designs allow fascinating properties when harnessed in specific real-world application. Herein, we demonstrate that 3D carbonized corncob (C-corncob) harmoniously coordinates light absorption, water supply, vapor escape, and efficiently utilizes the environmental energy to enhance the performance of the steam generation device due to its multilevel inside and side surface structures. The interfacial solar steam generation based on C-corncob achieves as high as 4.16 kg m−2 h−1 evaporation rate under 1.0 sun illumination and readily overcomes the salt deposition problem. These findings not only demonstrate the competence of the recrement corncob as the lost cost material for interfacial solar steam generation, but also provide inspiration for the creation of solar steam generation devices with the new concept. The carbonized corncob based solar vapor steam generator were successfully prepared through facile and simple carbonization process, along with deeply investigating the performance of the interfacial solar-driven steam generation of these carbon-based devices. The interfacial solar steam generation based on C-corncob achieves a higher evaporation rate under 1.0 sun illumination by Environmental Energy, more importantly, the devices overcome the limitation of sunshine duration by efficiently utilizing external energy as a full-time vapor generator. [Display omitted] • A high performance steam generator based on carbonized corncob has been developed. • The biomass based steam generator possesses unique hierarchical porous structures. • The 3D carbon steam generator allows environmental energy utilization. • The biomass based steam generator exhibits excellent salt resistence and long-term stability in sea water. [ABSTRACT FROM AUTHOR]

Despite the great advantages of interconnected porous architectures of three-dimensional carbon as functional materials, apparent common drawbacks restricting their widespread applications are high cost and non-renewable of the carbon precursors and complicated activation procedures. In this study, biomass-derived honeycomb-like multilayered carbon (HMC) is synthesized by electrospraying and direct carbonization for the first time. Poly (methyl methacrylate) (PMMA) is mixed with biomass-derived lignin, the only carbon source, to form lignin/PMMA microspheres and microbowls by electrospraying. One-step carbonization of prepared micromaterials to obtain ultralight HMC, and the microstructures and pore size of carbon materials are controllable by adjusting the applied voltage of electrospraying. The obtained HMC-13 by carbonization of lignin/PMMA microspheres possesses interconnected carbon skeleton, partially graphitized structure and hierarchical pore system composed of macropores, mesopores and micropores. Benefiting from the structural advantages, HMC-13 as electrode of supercapacitor delivers a high specific capacitance of 348 F g−1 at 0.5 A g−1 in aqueous electrolytes. Additionally, the supercapacitor exhibits excellent cycling stability with only 4% capacitance loss after 10 000 cycles. Based on these encouraging results, environmental friendliness and facile synthesis strategy, the biomass-derived ultralight porous carbon material holds great promise for facilitating wasted biomass utilization and developing sustainable energy products. [Display omitted] • A strategy combining electrospraying and carbonization to get carbon was developed. • The synthesized ultralight carbon possessed honeycomb-like multilayered structure. • The obtained carbon had partially graphitized structure and hierarchical pore system. • The prepared carbon as electrode exhibited excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Previous researches on carbon-based solar interfacial evaporation (SIE) have mainly focused on improving the solar absorption, neglecting the effect of water state on the SIE performance. This study proposes an easy strategy by combining carbonization and sulfonation using corncob as the carbon source and concentrated sulfuric acid (H 2 SO 4) as the sulfonating agent to obtain sulfonated carbonized corncob (SCC) samples. The intermediate water to free water (IW/FW) ratio in the range of 0.53–0.96 within SCC samples has been tailored, which depends on the amount of hydrophilic sulfonic acid groups grafted on SCC. It is found that the amount of hydrophilic sulfonic acid groups and porous structure should be optimal in SCC for high IW/FW ratio. The optimized sample named as SCC-2-4.5 with a high IW/FW ratio of 0.96 and similar surface area to carbonized corncob exhibits the low enthalpy of water evaporation of 1800 J g−1, achieving the evaporation rate of 3.16 kg m−2 h−1 and evaporation efficiency of 159%. Meanwhile, SCC-2-4.5 realizes an effective separation of Na+ and Cl−, thanks to the electrostatic repulsion caused by its negatively charged sulfonic acid groups. This study provides an effective technique for regulating water state for carbon-based SIE devices on the molecular level. Modulation of the ratio of intermediate water to free water (IW/FW) on sulfonated corncobs (SCCs) to improve the performance of evaporation devices was demonstrated. The IW/FW ratio of SCCs in the range of 0.53–0.96 were obtained by tailoring the amount of hydrophilic sulfonic acid groups. The optimized SCC sample with a high IW/FW ratio of 0.96 exhibits the low enthalpy of water evaporation of 1800 J g−1, achieving the evaporation rates of 3.16 kg m−2 h−1, evaporation efficiency of 159% and salt resistance value of 1.62 g. Above results show that the sulfonic acid groups play an important role in activating the water state and conferring salt resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

Gelatin, a natural macromolecular substance formed by the hydrolysis of collagen, offers the advantages of abundant resources and low cost. It is a good precursor for the synthesis of N, O-doped carbon materials. Although some gelatin-derived carbon materials have been used for electrochemical energy storage, there have been few studies for the mechanism of gelatin carbonization. In addition, the influence of heteroatoms and defects on the K-ion storage performance remains unclear. In this work, in situ and ex situ characterization methods have been used to study the mechanism of gelatin carbonization. The pathways leading to formation of the carbon framework, heteroatom doping and defect generation in gelatin-based carbons during the pyrolysis process have been clearly identified. Moreover, by means of DFT calculations and experimental measurements, it has been confirmed that heteroatoms and defects both play important roles in improving the storage performance of potassium ions. By virtue of its abundance of both heteroatoms and defects, our optimized anode shows better electrochemical performance than graphite anodes. This study not only clarifies our understanding of carbonization mechanism and mechanism of K-ion storage in carbon materials, but also provides pathways for the synthesis and applications of new carbon-based anode materials for alkali-ion batteries. The structural and compositional changes of gelatin during thermo-chemical conversion process have been investigated using in-situ and ex-situ characterization methods. Moreover, in-situ Raman spectroscopy are also used to analyze the K-ion storage performance of the GC anodes. [Display omitted] • The carbonization mechanism of GCs is detailly investigated. • In-situ and ex-situ methods are used to analyze the thermo-chemical conversion process. • DFT calculations unravels the effects of heteroatoms on K-ion storage performance. • The GC-800 anode shows good rate capability and cycling performance. [ABSTRACT FROM AUTHOR]

Carbonization process of pyromellitic dianhydride (PMDA)-4,4′-diaminodiphenyl ether (ODA)-type polyimide has been studied for decades. However, various reaction mechanisms have been proposed and the detailed mechanisms are still controversial. It is essential to understand the carbonized structures of PMDA-ODA-type polyimide before analyzing the defect structures in graphite. In this work, the carbonization mechanisms of polyimide heated at 1273 K or lower were unveiled and the methodology to analyze carbon materials containing nitrogen, oxygen, pentagons, and heptagons using computational spectral analysis combined with molecular dynamics simulation (ReaxFF) are exhibited. For example, the formations of isoimide and cyclic ether were estimated by ReaxFF, and the presence was supported by experimental and calculated X-ray photoelectron spectroscopy (XPS) and carbon-13 nuclear magnetic resonance (13C NMR) spectra of polyimide heated between 813 and 873 K. The formations of pentagons and heptagon, suggested by ReaxFF, were also supported by Raman and 13C NMR spectra of polyimide heated between 833 and 1273 K. This work also revealed that the previously reported structures were unstable and that amine in the basal plane was the most plausible structure in polyimide heated at 1073 K or higher, as clarified by XPS, ReaxFF, and the energy calculation. [Display omitted] [ABSTRACT FROM AUTHOR]

The nitrogen-doped carbons (NC) were prepared by a simple pyrolysis method using polyaniline as the precursor. The effect of carbonization temperature on the properties of the synthesized NC was investigated. The optimal temperature was determined as 600 °C according to the properties of the obtained materials and the performance on improving the methane production by the anaerobic sludge. When the optimal NC was used as the conductive medium in the anaerobic sludge, the methane yield and production rate were increased by 35% and 10%, respectively. The effect of the NC loading on the activity of the microorganisms was also investigated. It was found that the degradation of the organics in the bacteria was enhanced by adding NC. Moreover, the bacterial and archaeal communities were significantly affected by the added NC material, and Methanosaeta with the direct interspecific electron transfer (DIET) ability have been enriched in anaerobic sludge. This indicated that the NC materials with surface defects can improve the organics degradation and the microbial extracellular electrons transfer, thereby promoting the methane production during the anaerobic wastewater treatment. [Display omitted] • Nitrogen doped carbon was used as conductive medium in anaerobic system. • Nitrogen doped improved CH 4 production from anaerobic wastewater treatment. • Nitrogen doped enriched the microorganism with the DIET ability. [ABSTRACT FROM AUTHOR]

Despite the potential to lowering fabrication costs of pitch-based carbon fiber (CF) compared to polyacrylonitrile-based CF, large scale utilization is currently limited by the complexity in manufacturing. This is mainly due to the lack of consistency between the pitch structure/chemistry and CF properties under different processing conditions. Here, we employed full atomistic simulations based on reactive force fields to investigate the conversion of pitch precursors to CFs. It was found that at the carbonization stage, the consumption rates of precursors, gas formations, and solid yields (carbonized CFs) are all dependent on the composition and arrangement of molecular moieties in the precursor. Specifically, precursors with sp3 carbons in the cata-condensed core area have limited decomposition pathways (i.e., limited reaction sites), which leads to the formation of carbonized CFs with similar compositions. Furthermore, carbonized CFs possess distinct structural characteristics, and finally lead to the formation of CFs with different moduli. By analyzing CF crystallinity and elemental composition, general rationales are proposed for the selection of optimal precursors and processing conditions, and thus shed lights on parameter screening during industrial CF synthesis. For instance, inclusion of sp3 carbons in cata-condensed rings can be preferred over the presence of sp3 carbons on side chains. [Display omitted] [ABSTRACT FROM AUTHOR]

Even after centuries-old experience in carbonizing materials we can still learn new lessons and find new applications for carbonized materials. In the past decades, laser-assisted syntheses of materials have emerged as versatile tools for the fabrication of micro- and nanostructured functional devices. In this regard, laser-carbonization is of particular interest, as it provides a method for patterning eco-friendly and potentially biodegradable electronic materials for future applications in comparison to the state-of-the-art in flexible electronics. However, using molecular precursors for laser-carbonization has been a challenge for many years. We identified a set of three different precursors and conducted an in-depth morphological and compositional study to understand how molecular precursors must be prepared for the high-speed carbonization reactions used in laser-patterning. The resulting laser-patterned carbons (LP-C) or N-doped carbons (LP-NC) are different from their conventionally pyrolyzed reference products mostly in terms of morphology. A generally porous structure and a carbonization gradient induced by the top-to-bottom energy input are the most remarkable features. Additionally, the microstructure, the elemental composition and the resulting electronic properties are different as demonstrated by X-ray photoelectron spectroscopy (XPS) and wide-angle X-ray scattering (WAXS) analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

We present results from neutron-imaging studies of slow, vacuum pyrolysis of beech, poplar and conifer wood, and pelletized biomass from room temperature up to 1000 °C. A detailed and quantitative method to extract 2D (in situ neutron radiography, NR) and 3D (ex situ neutron computed tomography, NCT) information on structural transformation and elemental hydrogen content has been developed. NCT and X-ray tomography (XCT) experiments on a carbonized beech twig permitted comparison of the spatial distribution of hydrogen, better sensed by NCT, and carbon, oxygen, and heavier elements, better sensed by XCT. We have developed a methodology to directly compare structure and hydrogen-loss dynamics measured using neutron imaging with thermogravimetric analysis and differential thermogravimetry and thus can better understand the correlations between hydrogen and carbon release dynamics. While the methodology has been developed for the carbonization of biomass, we expect that it could be applied to in situ dynamic monitoring of other hydrogenous reacting systems with the appropriate spatial and temporal scales. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced composites are finding increased usage in a wide variety of applications, ranging from aerospace to energy harvesting to sporting goods and more. Carbon fiber manufacturing is an extremely time- and cost-intensive process with more than 70 processing variables. To better understand the processing-structure-property relationships and accelerate the improvement in carbon fiber mechanical properties, the integration of machine learning (ML) and experimental techniques is critical. The goal of this work is to investigate the use of ML models to map precursor information and carbonization process parameters to mechanical properties -- specifically, tensile strength and tensile modulus -- of carbon fibers. The experimental data consisted of 600 distinct points with 31 features. Four ML models were investigated viz. support vector regression (SVR), multi-layered perceptron (MLP) neural network, gradient boosted regression trees (GBRT), and recurrent neural network (RNN). The results indicate that ML can be used to approximate the underlying function describing the effect of the manufacturing process parameters on the carbon fiber tensile properties, with the RNN model outperforming all other models under consideration (R2 scores of 0.85 and 0.67 for tensile strength and tensile modulus, respectively). Image 1 [ABSTRACT FROM AUTHOR]

Binder-free mesoporous graphitic carbon composite films on polymer or metal substrates are attractive for high-surface-area electrodes to achieve superior device performances. However, rapid and large-area fabrication of such materials remains a significant challenge due to the harsh conditions required for the carbonization process. We report an efficient method that combines bottom-up precursor film assembly with photothermal processing using sub-millisecond light pulses generated from a xenon flash lamp. This approach enables the rapid carbonization and graphitization of precursor films over large areas at ambient bulk temperature to yield functional films while avoiding damage to the substrates. The films contain light-absorbing nanoparticles to convert light energy into heat, a block copolymer to template the porous structures via self-assembly, and phenol-fomaldehyde resin to form the carbon skeleton. Graphitic carbon nanoribbons embedded in a porous carbon matrix are created under mild conditions using iron nanoparticles as the catalyst during the millisecond photothermal process. The resulting composite films show excellent electrochemical properties and are demonstrated for use as high capacity lithium ion battery anodes. Image 1 • Millisecond photothermal preparation of mesoporous graphitic carbon/nanoparticle composite films from simple precursors • Mechanisms of iron catalyzed photothermal conversion elucidated. • Tunable porosity, nanoparticle loading and graphitic carbon inclusion for high-performance LIB electrodes. • Scalable process compatible with roll-to-roll manufacturing. [ABSTRACT FROM AUTHOR]

Graphene inclusion in a polymer matrix is a promising route to significantly enhance the mechanical properties of low-grade carbon fibers (CFs). Using ReaxFF molecular dynamics simulation, the atomistic mechanism leading to this enhancement is investigated. We demonstrate that the graphene edges along with the nitrogen and oxygen functional groups play a catalytic role and act as seeds to expedite alignment of the all-carbon rings, which are starting sites for the growth of graphitic structures. To examine the role of this proposed mechanism that enhances the graphitic structure of PAN/graphene CFs, we discuss the experimental results wherein the PAN/graphene CFs carbonized at 1250 °C demonstrate 91% (from 632 to 1207 MPa) increase in strength and 101% (from 88 to 177 GPa) enhancement in Young's modulus compared to PAN-based CFs carbonized at 1500 °C. These enhanced mechanical properties of low-grade carbon fibers achieved via graphene inclusion at decreased carbonization temperature provide a means to realize both energy savings and cost reduction. Image 1 The graphene edges play a catalytic role and act as seeds in expedite graphitic structure growth, while the graphene surface carbon atoms are relatively inactive due to their conjugated sp2 electronic configuration. [ABSTRACT FROM AUTHOR]

N-doped hierarchical carbon (NHC) composed of hierarchically arranged highly graphitic graphene shells with high surface/bulk ratio is demonstrated as a proof of concept, and utilized as carbon source in Cu–N–C catalysts. The special structure is contributed to Fe nanoparticles induced to PANI nanospheres, which serving as hard templates greatly alter the thermal decomposition/carbonization process of PANI. When employed as carbon source in Cu–N–C ORR catalyst, not only is the catalytic activity boosted as a result of highly loaded Cu centers anchored at the rather accessible sites to oxygen, the stability is greatly enhanced as well. Image 1 • Iron oxides alters the decomposition/carbonization process of PANI. • Hierarchically arranged graphene shells grants NHC with high surface/bulk ratio. • High surface/bulk ratio of NHC shows advantage in Cu anchoring. • Cu–NHC presents both high ORR activity and satisfying stability. [ABSTRACT FROM AUTHOR]

Lightweight, and broad and strong absorption are still a huge challenge for electromagnetic (EM) wave absorbers. Here, we propose a facile oxidative polymerization-carbonization strategy to synthesize O, S, N codoped carbon planar helixes for superior EM wave absorbers. The spiral cetyltrimethylammounium bromide crystallites act as a template for the in-situ oxidative polymerization of pyrroles into ordered PPy spiral nanowires. Sintering temperature (T s) was used to adjust the defects, heteroatoms, graphitization degree, and properties of the carbonized products. With T s varying from 400 °C to 800 °C, internal stress and heteroatom (N, O, S) content decreased, causing the decreased defect/dipole polarization and increased graphitization degree and conductivity loss. As a result, one broad high-frequency absorption band was exhibited by carbon planar helixes produced at 400 °C− 500 °C, two broad absorption bands were exhibited by those formed at 600 °C, and three absorption bands were exhibited by those formed at 700 °C − 800 °C. The carbon planar helix formed at 700 °C exhibited broader bandwidth (4.96 GHz), thinner sample thickness (1.4 mm), and stronger absorption (−35.44 dB) than those of other absorbers. The superior properties are attributed to a combination of dipole/defect polarization, interface polarization, conductivity loss, multiple scattering, and multiple LC-resonances generated from the unique planar helical structure, defects, heteroatoms, and local electric network. Image 1 • A facile oxidative polymerization-carbonization strategy for carbon planar helixes. • Modulation of the defects, heteroatoms, graphitization degree. • Investigating electromagnetic wave absorption capabilities. • Revealing the enhancement mechanism of the microwave absorption. [ABSTRACT FROM AUTHOR]

The desire for multivariable applications has encouraged extensive study to exploit multi-functional carbon materials owing to their superior physicochemical properties, wide availability, and massive productivity. In particular, the design of a porous architecture is the key to manipulating their function, thereby promoting the practicality. This paper suggests a simple and scalable synthetic process to prepare mesostructured porous carbon derived by pseudo metal-organic coordination. Inspired by metal-organic framework synthesis, the zinc ion is selected to function as both a mesostructure inducer and self-vanishing porogen, thereby enabling the direct carbonization of non-carbonizable precursors without complicated and environmental burden steps. The resulting porous carbon materials possess mesostructured morphologies, resembling diverse metal oxide crystals with distinct pore architectures, which can be tailored for various applications. Furthermore, the functionalities of the resulting mesostructured porous carbon are demonstrated by evaluating the adsorption behavior for large molecules and the electrochemical performance of the sulfur cathode for Li–S batteries. Image 1 [ABSTRACT FROM AUTHOR]

Low energy density is a fatal disadvantage of electric double-layer capacitor (EDLC). The improvement of the operation voltage of EDLCs is a more effective method to increase the energy density of EDLCs. When the operation voltage of EDLCs is higher than 2.7 V, the oxygen-containing functional groups on the surface of electrode materials (porous carbon) will decompose or chemically react with the electrolyte, causing significant deterioration of EDLC performance. In this paper, porous carbon with low oxygen content is prepared by using the potassium-assisted carbonization of chlorobenzene in Ar/H 2 mixed gas to improve withstanding voltage characteristic of porous carbon. By constructing a relatively closed and stable pyrolysis environment (employing the nickel crucible with a lid), using the carbonaceous precursor without oxygen atoms (chlorobenzene) and selecting reasonable carbonization operation atmosphere (Ar/H 2), the oxygen content of the as-prepared porous carbon (PC-KC-1000) is only 4.02 wt%. When the PC-KC-1000 sample is used as the electrode material of EDLCs, the operation voltage of EDLCs in the TEABF 4 /PC and EMIMBF 4 electrolytes is respectively 3.3 and 3.5 V, and the maximum energy density is respectively 53.5 and 64.4 Wh kg−1. This strategy provides a new idea for the preparation of porous carbon with low oxygen content. Image 1 [ABSTRACT FROM AUTHOR]

Gallium and many of its alloys remain in liquid phase across impressively wide temperature ranges. Here such liquid metals are proposed as reaction media for the carbonization of low thermal stability polymeric precursors at high temperatures. Plain and cross-linked polyvinyl alcohol are chosen as representatives of such polymers. We show that due to the immiscibility of organic carbons within the liquid metal phase, these polymers that would otherwise vaporize at elevated temperatures, can function as precursors for the formation of carbonaceous films. The thin polymeric films are placed in an intimate contact with the liquid metal surface before thermal processing and show amorphous to graphitic-like characteristics after carbonization. Graphitic-like properties were obtained when a high melting point graphitization catalyst, such as copper, was co-alloyed. The proposed work can be expanded to explore other metallic elements within the bulk of gallium-based alloys for the carbonization of polymeric precursors at large-scales. Image 1 • Polymers that do not carbonize otherwise can be 'capped' by liquid metals and thereby carbonized. • Gallium-based liquid metals exhibit selective miscibility to non-metallic elements. • Gallium, gallium-indium and gallium-copper were chosen as liquid metal reactors. • Carbon films with amorphous and graphitic characteristics were formed. • Inclusion of copper in liquid metal enhanced the graphitic characteristics of the films. [ABSTRACT FROM AUTHOR]

The wide application of carbon nanosheets (CNS) is still restricted by low production. Meanwhile, the accumulation of waste plastic generates serious environmental pollution. Nowadays, the conversion of waste plastic into two-dimensional CNS is regarded as a promising way to address these issues due to the high carbon content of waste plastic. However, this conversion process is still impeded by low-efficient catalysts so far. Herein, the highly efficient carbonization of waste polypropylene (PP) into CNS is achieved using a combined catalyst of ferrocene and sulfur. The carbonization process in sealed space ensures an ultrahigh carbon yield (62.8%) and a thin thickness (4–4.5 nm) of as-prepared CNS, even though little catalyst is used. After activation, the activated carbon nanosheets (ACNS) show a well-defined hierarchical porous structure with a large specific surface area (3200 m2 g−1) and a big pore volume (3.71 cm3 g−1). The ACNS based electrode delivers a high specific capacitance of 349 F g−1 at 0.5 A g−1. The fabricated symmetric supercapacitor manifests a high energy density of 23 Wh kg−1 at 225 W kg−1. These findings provide a reference for the efficient conversion of waste plastic into energy storage materials. Image 1 • Waste PP is converted into thin carbon nanosheets (4–4.5 nm) using combined catalyst. • Vapor-phase reaction endows the prepared CNS with a high carbon yield (62.8%). • Activated carbon nanosheets show a large specific surface area and a big pore volume. • A high specific capacitance with superior cycling stability is proved. • This work reports an efficient conversion of waste plastic into electrode material. [ABSTRACT FROM AUTHOR]

The rational and oriented design of a proper electrode structure is crucial for the realization of desirable properties. Herein, we report the design and synthesis of freestanding hybrid films that feature desirable one-dimensional (1D) structure and favorable electrochemical properties for Li-ions batteries (LIBs). Briefly, by offering a water-steam originated from the real-time thermal decomposition reactions during the carbonization to etch the nanofibers in-situ, the hierarchical porosity and N, P co-doping are simultaneously introduced into carbon nanofibers skeleton. The synergistic effect of these two defects engineering expose more active sites, which can provide a substantial pseudocapacitance to boost the lithium storage performance. In addition, the in-situ coating structure formed by electrospinning process is also helpful to alleviate the volume expansion of Fe 3 O 4. Therefore, the prepared hybrid films display the excellent results by delivering an areal capacity of 1.0 mA h cm−2 at 2 mA cm−2 after 200 cycles in the half-cell. Meanwhile, a practical coin-type full-cell also delivers an areal capacity of 0.62 mA h cm−2 at 0.5 mA cm−2 after 100 cycles. This work paves the way to constructing rational electrode materials with controllable defect engineering for energy-related applications. Image 1 • Steam etching was provided by real-time reactions during the carbonization. • N, P co-doping and porosity was introduced into carbon nanofibers by one step. • Synergistic effect of two defects engineering exposed more Li+ storage sites. • The exclusive pseudocapacitance boosted the areal capacity of Fe 3 O 4 @P–CNF. • A practical full-cell delivers an areal capacity of 0.62 mA h cm−2 at 0.5 mA cm−2. [ABSTRACT FROM AUTHOR]

Nitrogen-doped materials are known to possess unique functional properties, making these materials potentially useful for environmental applications, heterogeneous catalysis, and electronics. In this paper we constructed first principles-based models of various polyaromatic structures containing N functionalities to better understand the effect of these functional groups on char Raman spectra. The presence of N functional groups induces active vibrations in the regions between 1400 and 1550 cm−1 and 1605-1650 cm−1. We used these insights to inform the deconvolution of N-doped cellulose char produced between 350 and 700 °C using cellulose/melamine blends 2:1. A consistent increase in the intensity of the D and G bands is observed with temperature, which is related to an increase in size of the aromatic cluster. A consistent decrease in the A (the valley region) band is related to the loss of heteroatoms (mainly N and O) as the carbonization temperature increases from 350 to 700 °C. Although the modeling results reported in this manuscript are used to inform the deconvolution of N-doped char Raman spectra, they are also relevant to study other nanocarbon-based materials. Image 1 [ABSTRACT FROM AUTHOR]

Carbonized polyaniline/nanodiamond hybrids were synthesized using an in situ polymerization and carbonization method, in which polyaniline aided to stabilize nanodiamond and prevent it from re-aggregation. Polyaniline also acted as nitrogen source, constructing nanodiamond interface/surface C⋯N hybridization during the carbonization. Q = N and C⋯N = Q groups, which could enhance the dielectric polarization, were proved to exist in the carbonized hybrids. On the other hand, doping nitrogen into nanodiamond resulted in ferromagnetism, which could couple the dielectric and magnetic dissipation. The carbonized hybrids exhibited remarkable ultrabroad-band electromagnetic absorption. The optimal reflection loss peak could reach −46.0 dB at 12.2 GHz and the bandwidth below −10 dB was 12 GHz covering 6–18 GHz. The broadband and high electromagnetic absorption were mainly attributed to the Q = N and C⋯N = Q groups' dual polarization enhancement, nitrogen-doping induced magnetic effects, as well as the collaborative nitrogen-doped interface network. This work provides novel referencing path for the design of broadband electromagnetic absorption materials, especially for heteroatom doped carbon nanomaterials. Image 1 • Nitrogen doped ND were realized through in situ polymerization and carbonization of PANi/ND. • Metal-free carbonized PANi/ND showed clear ferromagnetic behaviour. • The optimal reflection loss reached − 46.0 dB at 12.2 GHz and the bandwidth below − 10 dB was 12 GHz. [ABSTRACT FROM AUTHOR]

We report an ultrafast transformation of poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers into carbon fibers (CFs) by direct carbonization that eliminates high-cost oxidation in traditional CF conversion. Ultrafast heating and cooling render PBO-derived CFs superlative mechanical properties. ReaxFF atomistic-scale reactive molecular dynamics simulations unveil the PBO to CF conversion mechanism in which ultrafast heating suppresses the O-contained gas release, facilitating all-carbon rings alignment during the carbonization of PBO. These findings provide new guidelines for identifying and evaluating alternative CF precursors and fresh perspectives on smart manufacturing of CFs. Image 1 [ABSTRACT FROM AUTHOR]

Blends of polyacrylonitrile (PAN) and poly(p-phenylene-2,6-benzobisoxazole) (PBO) as precursors may offer an opportunity to reduce the cost of carbon fiber (CF) production. The all-carbon ring formations and volatile gas production during the heating and carbonization for 9 PAN/PBO blend precursors with varying mixing ratios are studied via the ReaxFF reactive molecular dynamics simulations. Evolutions of oxygen-containing (O-containing) and nitrogen-containing (N-containing) groups are detailed, in order to reveal the reaction mechanisms of the O and N-based CF precursors. Particularly, the O-containing groups are identified to be more efficient for initiating the carbonization, whereas N-containing groups are far longer retained in the graphitic materials and play a key role in capturing and converting carbon radical species into the graphitic networks. Additionally, the PAN/PBO blend precursor with a mole ratio of 1:1 is compared with the pre-oxidized PAN, PAN, and PBO. It is found that the PAN/PBO blends could be a promising alternative for the cost-effective PAN-based CF precursors, since they can decrease the cost of the CF production by means of: (a) eliminating the pre-oxidation process, (b) having considerable all-carbon ring formations within a short period, and (c) having a relatively fast conversion rate, reaching 95% 6-membered carbon ring formation. Image 1 [ABSTRACT FROM AUTHOR]