Search

[Display omitted] Regarding carbon-based electrodes, simultaneously establishing a well-defined meso -porous architecture, introducing abundant hetero-atoms and improving the graphitization degree can effectively enhance their capacitive performance. However, it remains a significant challenge to achieve a good balance between defects and graphitization degree. In this study, the porous structure and composition of carbon materials are co-optimised through a 'dual-function' strategy. Briefly, K 3 Fe(C 2 O 4) 3 and H 3 BO 3 were hybridised with a gelatin aqueous solution to form a homogeneous composite hydrogel, followed by lyophilisation and carbonisation. Owing to the dual functionality of raw materials, the graphitization, activation and hetero-atom doping processes can occur simultaneously during a one-step high-temperature treatment. The resultant carbon material exhibits a high graphitization degree (I D /I G = 0.9 ± 0.1), high hetero-atom content (N: 9.0 ± 0.3 at.%, B: 6.9 ± 0.5 at.%) and a large specific area (1754 ± 58 m2/g). The as-prepared electrode demonstrates a superior capacitance of 383 ± 1F g−1 at 1 A/g. Interestingly, the cyclic voltammetry (CV) curves exhibit a distinctive pair of broad redox peaks, which is uncommon in KOH electrolyte. Experiment data and density functional theory (DFT) simulation verify that N-5, B co-doping enhances the activity of the faradic reaction of carbon electrodes in KOH electrolyte. Furthermore, the fabricated Zn-ion hybrid supercapacitor (ZHSC) based on this carbon electrode delivers a high-energy density of 140.7 W h kg−1 at a power density of 840 W kg−1. [ABSTRACT FROM AUTHOR]

The utilization of high‐sulfur coal, especially high‐organic coal, has always been a difficult hot spot in the energy field. To study the influence of sulfur in coal on coal‐based graphite products, a series of coal samples with different sulfur content and different degrees of coalification were collected for proximate analysis, ultimate analysis, and sulfur species analysis. The structural characteristics of coal‐based graphite products were analyzed by X‐ray diffraction (XRD). The relationships between the sulfur in coal and the yield (Y), graphitization degree (G), cell diameter (La), and stacking height (Lc) of coal‐based graphite products were explored. The yield of coal‐based graphite ranges from 8.92 % to 64.45 %, and it was found that the yield of coal‐based graphite is not only affected by the degree of coalification, fixed carbon content, and volatile matter content of coal but also significantly inhibited by organic sulfur in coal when the reflectance is less than 2.00 %. The graphitization degree (G) of coal‐based graphite is distributed between 76.02 % and 91.02 %, and positively related to the degree of coalification, and negatively related to the content of volatile matter. Organic sulfur in coal is an unfavorable factor for the graphitization degree (G) of coal‐based graphite. Both the cell diameter (La) and stacking height (Lc) of coal‐based graphite are positively correlated with the degree of coalification and negatively correlated with the volatile matter content in coal. Organic sulfur in coal plays an important inhibitory role on the cell diameter (La) of coal‐based graphite. Still, it has almost no effect on the stacking height (Lc) of coal‐based graphite, resulting in a low ratio of horizontal‐to‐vertical (La/Lc), which is not conducive to the horizontal development of coal‐based graphite cells. [ABSTRACT FROM AUTHOR]

Silicon oxycarbide (SiOC) is a promising anode material for lithium‐ion batteries, owing to the high capacity and superior structural stability. However, the application of SiOC anode is limited by its low conductivity and poor rate performance. Here, SiOC anodes were prepared by the pyrolysis of silicone resin (RSN‐217) at different temperatures (700, 850, 1000, and 1150° C), and the effect of graphitization degree and Si─O─C network on the electrochemical performance of SiOC anodes was investigated. The elemental and structural characteristics of the pyrolyzed SiOC ceramics at different temperatures were inspected using a broad spectrum of characterization techniques, and electrochemical performance testing methods, such as cyclic voltammetry and galvanostatic charge/discharge, were conducted on SiOC anode. SiOC‐1000 showed excellent electrochemical performance due to the highest graphitization degree of free carbon phase and the highest content of SiO2C2 and SiO3C units. Considerable research effort laid a foundation for exploring the lithium storage mechanism of SiOC anode. [ABSTRACT FROM AUTHOR]

To enhance the synergistic effect of phosphorus (P) and nitrogen (N) on flame retardant property, four different phytic acid-based NP flame retardants (FR-PAN) were manufactured using phytic acid and urea with various molar ratios, ranging from 1:3 to 1:12. The FR-PAN water solution was used to impregnate poplar wood under vacuum condition, and the thermal degradation performance of the FR-PAN treated wood were investigated. Compared to untreated wood, the PAN-6 (molar ratio is 1:6) group showed a reduction of 57.1% in total heat release and 80.0% in total smoke release. In the combustion, due to the introduction of P and N, FR-PAN generates O=P/C-O/C-P/C-N bonds, forming highly graphitized char residues, which effectively isolate the entry of oxygen and heat and play a good protective role in the condensed phase. Morphological and chemical analysis of the residual char layer revealed that the introduction of P and N elements formed a more stable hybrid structure, significantly improving the thermal stability of the char layer. Among them, the PAN-6 group exhibited the highest char layer stability, indicating optimal synergistic effects of nitrogen and phosphorus under these conditions.

To enhance the synergistic effect of phosphorus (P) and nitrogen (N) on flame retardant property, four different phytic acid-based NP flame retardants (FR-PAN) were manufactured using phytic acid and urea with various molar ratios, ranging from 1:3 to 1:12. The FR-PAN water solution was used to impregnate poplar wood under vacuum condition, and the thermal degradation performance of the FR-PAN treated wood were investigated. Compared to untreated wood, the PAN-6 (molar ratio is 1:6) group showed a reduction of 57.1% in total heat release and 80.0% in total smoke release. In the combustion, due to the introduction of P and N, FRPAN generates O=P/C-O/C-P/C-N bonds, forming highly graphitized char residues, which effectively isolate the entry of oxygen and heat and play a good protective role in the condensed phase. Morphological and chemical analysis of the residual char layer revealed that the introduction of P and N elements formed a more stable hybrid structure, significantly improving the thermal stability of the char layer. Among them, the PAN-6 group exhibited the highest char layer stability, indicating optimal synergistic effects of nitrogen and phosphorus under these conditions. [ABSTRACT FROM AUTHOR]

In order to achieve the high-value utilization of heavy tar for the production of enhanced-performance graphite foam carbon, the carbon mesophase was ready from the heavy component of low-temperature coal tar, and the coal tar was modified by styrene-butadiene-styrene (SBS), polyethylene (PE) and ethylene-vinyl-acetate (EVA) copolymers. The order degree of the carbonite mesophase was analyzed using a polarizing microscope test, Fourier transform infrared spectroscopy and X-ray diffraction to screen out the most suitable copolymer type and addition amount. Furthermore, the mechanism of modification by this copolymer was analyzed. The results showed that adding SBS, PE and EVA to coal tar would affect the order of carbonaceous mesophase; however, at an addition rate of 10.0 wt.%, the linear-structure SBS copolymer with a styrene/butadiene ratio (S/B) of 30/70 exhibited the optimal degree of ordering in the carbonaceous mesophase. Its foam carbon prepared by polymer modification is the only one that forms a graphitized structure, with d002 of 0.3430 nm, and the maximum values of Lc and La are 3.54 nm and 2.22 nm, respectively. This is because, under elevated pressure and high-temperature conditions, SBS underwent chain scission, releasing a more significant number of methyl and other free radicals that interacted with the coal tar constituents. As a result, it reduced the affinity density of heavy coal tar molecules, enhanced fluidity, promoted the stacking of condensed aromatic hydrocarbons and increased the content of soluble carbonaceous mesophase, ultimately leading to a more favorable alignment of the carbonaceous mesophase. [ABSTRACT FROM AUTHOR]

The N, S dual-doped porous graphitic carbon materials with the high graphitization degree were synthesized from the light fraction of coal tar pitch and waste sponge through a facile "killing two birds with one stone" process. The suitable N and S doping not only can provide extra electroactive sites, but also can improve the storage capacity of Zn ions through the decrease in E a value for LC-750 cathode. [Display omitted] • The N, S dual-doped porous graphitic carbon is prepared via a "killing two birds with one stone" strategy. • The LC-750 exhibits superior pore structures and high graphitization degree. • The LC-750 cathode shows high capacity and excellent performance in AZICs. • The N and S incorporation enhances the Zn2+ adsorption ability and charge transfer behavior. Emerging aqueous zinc–ion hybrid capacitors (AZICs) are considered a promising energy storage because of their superior electrochemical performance. The pore structure, suitable heteroatom content, and graphitization degree (GD) of carbon-based cathodes significantly influence the electrochemical performance of AZICs. The N, S dual-doped porous graphitic carbon materials (LC-750) with the combined characteristics of high GD (1.11) and large specific surface area (1678.38 m2 g−1) are successfully developed by a facile "killing two birds with one stone" strategy using K 3 Fe(C 2 O 4) 3 ·3H 2 O as the activating and graphitizing agent, and waste sponge (WS) and coal tar pitch (CTP) as the heteroatom and carbon resource, respectively. Results show that the LC-750 cathode displays high capacities of 185.3 and 95.2 mAh g−1 at 0.2 and 10 A g−1. Specifically, the assembled LC-750//Zn capacitor can offer a maximal energy density of 119.5 Wh kg−1, a power density of 20.3 kW kg−1, and a capacity retention of 87.8% after 15,000 cycles at 10 A g−1. Density functional theory simulations demonstrate that N and S dual-doping can promote the adsorption kinetics of Zn ions. This design strategy is a feasible and cost-effective method for the preparation of dual heteroatom-doped graphitic carbon electrodes, which enables recycling of WS and CTP into high-valued products. [ABSTRACT FROM AUTHOR]

In this study, carbon-rich SiCN (Ni 3 Si) ceramic fibers (CSCF) were prepared through electrospinning and low-temperature (700–1000 °C) polymer derivation, and the effect of pyrolysis temperature on carbon content, carbon graphitization degree, dielectric properties and microwave (MW) absorption properties of fibers was explored. The results show that increasing pyrolysis temperature is conducive to the graphitization of carbon in fibers, but it also reduces the content of polyvinylpyrrolidone (PVP) derived carbon in the material. The synergistic relationship between the carbon content and carbon graphitization degree of CSCF obtained by pyrolysis at 800 °C was the best, benefiting from which its impedance matching ability is properly cooperated with the MW attenuation and its widest effective absorption bandwidth (EAB W) can achieve 4.6 GHz at a thickness of 1.9 mm. Compared with SiCN-based composite ceramic fibers obtained by pyrolysis at high temperature (more than 1000 °C), the ceramic fiber prepared in this study had a significantly improved EAB W even at a reduced introduction amount of metal element. In addition, the as-synthesized fiber precursor (FP) has high flexibility, based on which the macro-morphology of the material can be tailored more easily, to obtain the devices made of ceramic fibers with various complex shapes. The experimental ideas and conclusions of this work are of great significance for expanding the application of SiCN ceramic based composites in the field of MW absorption in the future. [ABSTRACT FROM AUTHOR]

Two X-ray diffraction methods were chosen to determine the degree of structural order (degree of graphitization) of natural carbonaceous matter. Factors influencing the graphitization processes during the progressive and regressive stages of metamorphism are examined. The correlation of the degrees of structural order of the carbonaceous material with the sequence of mineral growth allows the metamorphic history of the graphite-bearing rocks to be traced. The obtained data can be used for the evaluation of graphite as a raw material. [ABSTRACT FROM AUTHOR]

Hydrovoltaic effect is an innovative route to acquire electric energy from low-quality energy of water. Carbonized wood has shown great potential in hydrovoltaic conversion for the natural directional microtube structure which can induce sustaining water flow. But the induced-current, key performance of the hydrovoltaic effect, was still limited by intrinsic resistance of carbonized wood. To reduce the intrinsic resistance and promote the carrier migration, graphitizing as a proved method is used to improve the hydrovoltaic current. In this work, the carbonized wood was graphitized in different degree through transition metal catalytic method to investigate the influence. Double influence of graphitizing modification on hydrovoltaic conversion was verified. Moderately graphitizing modification can simultaneously promote the carrier to migrate and accumulate at double electric layer (DEL) interface, which benefits hydrovoltaic effect. But excessive modification shows a negative effect on carrier accumulation and reduces the hydrovoltaic performance. Comparing to the untreated carbonized wood, the maximal open-circuit voltage of graphitized carbonized wood can reach ~2.4 times higher (~0.47 V), while short-circuit current can be further enhanced to a notable ~27 times increase (~35 μA), demonstrating the remarkable enhancement of graphitizing modification on induced current. [ABSTRACT FROM AUTHOR]

The thermal deactivation of diesel soot particles exerts a significant influence on the control strategy for the regeneration of diesel particulate filters (DPFs). This work focused on the changes in the surface functional groups, carbon chemical state, and graphitization degree during thermal treatment in an inert gas environment at intermediate temperatures of 600°C, 800°C, and 1000°C and explore the chemical species that were desorbed from the diesel soot surface during thermal treatment using a thermogravimetric analyser coupled with a gas-chromatograph mass spectrometer (TGA-GC/MS). The surface functional groups and carbon chemical state were characterized using Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The graphitization degree was evaluated by means of Raman spectroscopy (RS). The concentrations of aliphatic C–H, C–OH, C=O, and O–C=O groups are reduced for diesel soot and carbon black when increasing the thermal treatment temperature, while the sp2/sp3 hybridized ratio and graphitization degree enhance. These results provide comprehensive evidence of the decreased reactivity of soot samples. Among oxygenated functional groups, the percentage reduction during thermal treatment is the largest for the O–C=O groups owing to its worst thermodynamic stability. TGA-GC/MS results show that the aliphatic and aromatic chains and oxygenated species would be desorbed from the soot surface during 1000°C thermal treatment of diesel soot. [ABSTRACT FROM AUTHOR]

In order to achieve the high-value utilization of heavy tar for the production of enhanced-performance graphite foam carbon, the carbon mesophase was ready from the heavy component of low-temperature coal tar, and the coal tar was modified by styrene-butadiene-styrene (SBS), polyethylene (PE) and ethylene-vinyl-acetate (EVA) copolymers. The order degree of the carbonite mesophase was analyzed using a polarizing microscope test, Fourier transform infrared spectroscopy and X-ray diffraction to screen out the most suitable copolymer type and addition amount. Furthermore, the mechanism of modification by this copolymer was analyzed. The results showed that adding SBS, PE and EVA to coal tar would affect the order of carbonaceous mesophase; however, at an addition rate of 10.0 wt.%, the linear-structure SBS copolymer with a styrene/butadiene ratio (S/B) of 30/70 exhibited the optimal degree of ordering in the carbonaceous mesophase. Its foam carbon prepared by polymer modification is the only one that forms a graphitized structure, with d002 of 0.3430 nm, and the maximum values of Lc and La are 3.54 nm and 2.22 nm, respectively. This is because, under elevated pressure and high-temperature conditions, SBS underwent chain scission, releasing a more significant number of methyl and other free radicals that interacted with the coal tar constituents. As a result, it reduced the affinity density of heavy coal tar molecules, enhanced fluidity, promoted the stacking of condensed aromatic hydrocarbons and increased the content of soluble carbonaceous mesophase, ultimately leading to a more favorable alignment of the carbonaceous mesophase.

Mesocarbon microbead-silicon carbide (MCMB-SiC) composites were prepared by hot-press sintering (2100 °C/40 MPa/1 h) with two different graphitized MCMBs as the second phase, which exhibited good self-lubricating properties. The effects of the graphitization degree of the MCMBs on the microstructure and properties of the composites were investigated contrastively. The results showed that the composites that added raw MCMBs with a low degree of graphitization had excellent self-sintering properties, higher densities, and better mechanical properties; by comparison, the composites that added mature MCMBs with a high degree of graphitization, which has regular and orderly lamellar structures, not only had good mechanical properties but also exhibited a lower and more stable dry friction coefficient (0.35), despite the higher wear rate (2.66 × 10−6 mm3·N−1·m−1). Large amounts of mature MCMBs were peeled off during the friction process to form a uniform and flat graphite lubricating film, which was the main reason for reducing the dry friction coefficient of the self-lubricating composites and making the friction coefficient more stable. [ABSTRACT FROM AUTHOR]

[Display omitted] • Overview of synthesis methods for multicolor carbon dots emphasizing on machine learning. • Summary of systematic characterization techniques for multicolor carbon dots. • Summary of the mechanisms that underlie multicolor luminescence in carbon dots. • Review on advancements in simultaneous multicolor applications of carbon dots. Multicolor carbon dots (MCDs) have emerged as prominent carbon nanomaterials due to their unique properties, which include good biocompatibility, high photostability, tunable luminescence, and a wide range of applications in sensing, biological imaging, light-emitting diodes, and anti-counterfeiting. However, there is currently a lack of comprehensive reviews addressing the structural origins and key factors that control the mechanisms behind the multi-emission of carbon dots, as well as innovative advancements in simultaneous multicolor applications. This mini-review aims to fill this gap by highlighting recent advancements in MCDs over the past five years (2018 to 2024). We provide a concise overview of systematic classification, controllable synthesis, and characterization techniques for MCDs. We then emphasize the multicolor emission characteristics of MCDs and the factors influencing them, such as surface state, quantum confinement effect, and graphitization degree. Additionally, we discuss simultaneous multicolor applications of MCDs and their potential in various fields, the current challenges and perspectives on MCDs will be discussed as well. By acquiring a profound understanding of the structure-performance relationship and employing suitable adjustment methods, it is anticipated that this review will inspire and guide future research endeavors in the tailored design of MCDs. [ABSTRACT FROM AUTHOR]

As soot particles from incomplete combustion of fossil fuels pose a great threat to human health, the development of low-carbon or zero-carbon alternative fuels is essential to mitigate climate change. An experimental and numerical study on the pyrolysis properties of ammonia and ethylene mixtures is conducted, focusing on the properties of soot generated by pyrolysis under different conditions and the coupling relationship between soot properties and soot precursors. The results show that the graphitization degree of soot particles generated at higher pyrolysis temperatures is enhanced, but the oxidation reactivity is decreased. When ammonia is blended, the graphitization of soot decreases and the oxidation reactivity increases. The peak mole fractions of soot precursors are negatively correlated with the graphitization degree of soot particles as the temperature increases.

[Display omitted] • Lightweight carbon foam bulk with controllable graphitization degree were prepared. • The regulation of dielectric loss based on the graphitization degree was proposed. • The EAB of 3.63 GHz, EMI SE of 35.13 dB, and strength of 11.73 MPa were achieved. • The interfacial polarization between graphite/amorphous carbon exists in the polarization loss. The graphitization degree is of great importance for determining the electromagnetic (EM) wave attenuation loss behavior. The conductive loss is considered to be the mechanism resulting from tailoring the graphitization degree. There is a lack of in-depth research on the dipole polarization caused by defects and functional groups and the interface polarization caused by graphite/amorphous carbon. Herein, lightweight carbon foam (CF) bulk derived from mesophase pitch was prepared to clarify the effect of the graphitization degree systematically. The results demonstrate that with an increase graphitization degree, the interfacial polarization improves and dipole polarization decreases. The synergistic effect of conduction loss and dipole and interfacial polarization dominates the impedance matching and further changes the EM loss behavior of CFs. Particularly, the minimum reflection loss is − 16.69 dB and effective absorption bandwidth is 3.63 GHz, the EM interference shielding effectiveness attains 35.13 dB and the compressive strength is up to 11.73 MPa when the optimal graphitization degree is achieved. Therefore, this work elucidates the effect of the interface polarization of graphite/amorphous carbon, thus providing a valuable insight into the design of advanced carbon-based materials for EM wave absorption and shielding. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced carbon matrix (C f /C) composites have demonstrated great significance in many fields, especially in aircraft and automobiles as brake materials. The surface physical/chemical states of C f /C composites significantly affect their tribological properties. Although ultrafast laser machining technology has been proven to be an effective method for modifying material surfaces, there are some issues concerning the ultrafast laser surface treatment of C f /C composites and the adjustment of their tribological properties by laser treatment. Here, the 3D woven C f /C composites were treated with an infrared picosecond laser. The effects of machining parameters on the surface microscopic morphology, chemical compositions, and graphitization degree were investigated. The experiment results indicated that the ultrafast laser treatment could eliminate surface defects, improve surface quality, and reduce the porosity of the C f /C composites due to photothermal-mechanical ablation. More importantly, the laser-induced photothermal effects led to a graphitization transformation of C f /C composites from a disordered turbostratic structure into an ordered graphite structure with an increased graphitization degree. The abundant micro-nano structures and the graphitization transformation on the C f /C composite surface contributed to forming a complete and dense friction film on the C f /C composites. Therefore, the laser-treated C f /C composites showed lower COF, higher wear rate, and more stable tribological properties. This study demonstrated a method to adjust the tribological properties of C f /C composites by ultrafast laser surface treatment, which showed great significance for the surface treatment and tribological property enhancement of C f /C composites. [ABSTRACT FROM AUTHOR]

Electron transfer pathways have been verified as overriding regimes when peroxydisulfate (PDS) was activated by porous carbon. The incorporation of graphitic structure into carbon matrix was favorable to the rapid electron transfer, but excessive graphitization would deteriorate the specific surface area (SSA), weakening the catalytic performance. The reasonable trade-off between SSA and graphitization degree was necessary and challenging for the preparation of efficient carbon based PS-activators. Herein, a series of graphitic porous carbon with discrepant SSA and graphitic structure were fabricated. The incorporation of graphitization tracks into ultra-thin edges on porous carbon film was verified by multifarious structural characterization. After trade-off, the optimum catalyst exhibited superior catalytic performance with degradation rate constant (k obs) exceeding that of ungraphitized precursor by up to 16.0 times. Mechanistic investigations substantiated that the sufficient SSA of catalyst provided favorable conditions for its affinity towards PDS and sulfadiazine (SDZ), resulting in the formation of PDS* complexes and SDZ adsorption, while the appropriate graphitization degree ensured the reinforced electron transfer rate, which collectively accelerated SDZ oxidation through electron-transfer pathway. The multivariate linear regression model linking k obs to SSA and graphitization degree was established providing basis to construct efficient catalysts for PDS activation. [Display omitted] • A series of graphitic porous carbon were fabricated. • The sufficient SSA of catalyst accelerated its affinity to PDS and SDZ. • The appropriate graphitization degree ensured the reinforced electron transfer rate. • Reactive complexes were the foremost active species for catalytic oxidation. • The multivariate linear regression model was established. [ABSTRACT FROM AUTHOR]

In recent years, Co, N co-doped carbon (Co–N–C) materials as oxygen reduction reaction (ORR) catalysts have attracted great attention because of their good ORR stability as well as decent activity. Co-doped zeolitic imidazolate framework-8 (Co@ZIF-8) as the precursor for synthesizing Co–N–C has attracted great interest recently. Co@ZIF-8 synthesis method may affect the properties of the as-synthesized Co@ZIF-8 precursors, which will surely affect the properties and ORR performance of Co@ZIF-8-derived Co–N–C catalysts. Herein, three methods, viz. room-temperature stirring method, reflux method, and hydrothermal method, were used to synthesize Co@ZIF-8 precursors. Physical characterization shows that the synthesis method has a great influence on the textural properties, composition, and graphitization degree of the as-synthesized Co–N–C catalysts. Electrochemical characterization shows that Co–N–C-R synthesized with reflux method exhibits an onset potential (E onset) of 0.905 V, a half-wave potential (E 1/2) of 0.792 V and a limiting current density (J L) of 5.85 mA cm−2 in acidic media, which are higher than those of Co–N–C–S (E onset = 0.870 V, E 1/2 = 0.770 V, J L = 4.71 mA cm−2) and Co–N–C–H (E onset = 0.892 V, E 1/2 = 0.785 V, J L = 4.68 mA cm−2) synthesized with room-temperature stirring method and hydrothermal method, respectively. The better ORR activity observed on Co–N–C-R can be attributed to its larger graphitization degree and larger mesopore volume. Catalytic stability test shows that Co–N–C-R has negligible activity loss after 5000 potential cycles. This work demonstrates that reflux method is a more suitable method for synthesizing Co–N–C catalysts for ORR. • Three methods are used to synthesize Co-doped ZIF-8 (Co@ZIF-8) precursors. • Co@ZIF-8-R synthesized with reflux method is more suitable for Co–N–C synthesis. • Co@ZIF-8-R-derived Co–N–C-R exhibits an E 1/2 of 0.792 V in acidic media. • Co–N–C-R shows negligible activity loss after 5000 potential cycles. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Coaly graphite is an important natural graphite resource that derived from coal under a natural process that associated with igneous intrusion. Flake graphite is usually used for the chemical synthesis of graphene oxide (GO), the main precursor for preparation of graphene, but few papers pay attention to preparing GO using coaly graphite. In this paper, four kinds of natural coaly graphite with different graphitization degrees were exposed to a modified Hummer’s oxidation method to prepare GO. The flake graphite sample was also used for comparison. The results showed that the structural change process from graphite to GO were significantly affected by the graphitization degree of the original coaly graphite. The relationship between yields of GO and graphitization degrees of the coaly graphite was explored. The mechanism of why the graphite with low graphitization degrees cannot be totally oxidized was proposed. Coaly graphite with a graphitization degree of higher than 80% was easier to be oxidized and yielded the same amount of GO as the flake graphite did, suggesting it is the potential substitute for the flake graphite to produce GO in bulk quantities.

Mesocarbon microbead-silicon carbide (MCMB-SiC) composites were prepared by hot-press sintering (2100 °C/40 MPa/1 h) with two different graphitized MCMBs as the second phase, which exhibited good self-lubricating properties. The effects of the graphitization degree of the MCMBs on the microstructure and properties of the composites were investigated contrastively. The results showed that the composites that added raw MCMBs with a low degree of graphitization had excellent self-sintering properties, higher densities, and better mechanical properties; by comparison, the composites that added mature MCMBs with a high degree of graphitization, which has regular and orderly lamellar structures, not only had good mechanical properties but also exhibited a lower and more stable dry friction coefficient (0.35), despite the higher wear rate (2.66 × 10−6 mm3·N−1·m−1). Large amounts of mature MCMBs were peeled off during the friction process to form a uniform and flat graphite lubricating film, which was the main reason for reducing the dry friction coefficient of the self-lubricating composites and making the friction coefficient more stable.

Building structures are exposed to direct sunlight for a long time, accumulating a large amount of low-grade thermal energy, which aggravates environmental pollution and energy consumption. Thermoelectric cement-based composites can realize the interconversion of thermal and electrical energy, showing great potential benefits in large-scale heat collection and energy conversion. Although a lot of exploration and research has been carried out on the thermoelectric properties of cement-based composites reinforced with carbon materials, the contribution of the characteristics of carbon materials, such as the graphitization degree, to the thermoelectric properties of cement-based composites is still unclear. In this article, the graphitization degree of expanded graphite (EG) was modulated by etching EG with an acid solution. The low graphitization degree improves the effective mass of carriers and aggravates the electron and phonon scattering at the interface of EG/cement-based composites. Low thermal conductivity was obtained while increasing the Seebeck coefficient of EG/cement-based composites. The power factor (17.1 μW m -1 K -2 ) and thermoelectric figure of merit (2.95 × 10 -3 ) of the sample are increased by 18.6 times and 44.2 times, respectively, achieving the highest thermoelectric performance in cement-based composites reinforced with carbon materials. This study provides a direction for improving the thermoelectric properties of cement-based composites by structural regulation of carbon materials.

The removal by adsorption of methylene blue dye from water using two‐dimensional (2D) (graphene oxide and reduced graphene oxide) and three‐dimensional (3D) (graphite and graphite oxide) carbon structures was studied. Two graphites with different degrees of graphitization were used to evaluate the significance of the carbon structural order in the adsorption efficiency, and therefore, the economic repercussions, because the degree of graphitization is related with the cost. Graphene oxides showed the best performance in methylene blue adsorption, with a removal of around 90%. The adsorption process was strongly influenced by the surface oxygenated groups, and electrostatic interaction was the main mechanism of adsorption. The degree of graphitization of the precursor does not have a strong influence on the adsorption results of methylene blue. Thus, graphene oxide with a lower degree of graphitization represents an economical and efficient adsorbent for the removal of methylene blue from water. The kinetic study was realized in pseudo‐first order, pseudo‐second order, and Elovich kinetic models in their linear and non‐linear forms. According to the determination coefficient and the standard deviation, the experimental data were best fitted to the Elovich model in its non‐linear form. [ABSTRACT FROM AUTHOR]

• The addition of ammonia decreases diameters of primary particles and promotes the regularity degree of soot. • The use of ammonia increases the degree of graphitization, and decreases the ratio of sp3/sp2 in amorphous carbon and carbon atoms. • The proportion of oxygenated functional groups decreases with the addition of ammonia. • The use of ammonia decreases the oxidation activity. Ammonia, as a non-carbon fuel, has been regarded as an alternative fuel for combustion. In this investigation, the effect of ammonia on the soot properties such as morphology, nanostructure, graphitization degree, surface functional groups, and oxidation energy in a laminar ethylene flame has been studied using different detection techniques at 15 mm and 30 mm height above burner (HAB). The results show that the soot basically appears as a chain-like aggregate, which is composed of several tens of primary particles, and it also finds that the use of ammonia decreases diameters of primary particles, the diameter of A60 (ethylene with 60 ml/min ammonia) decreases by 28.0 % compared with that of A0 (ethylene without ammonia) at 30 mm HAB. Moreover, the addition of ammonia promotes the regularity degree of soot, slightly increases the mean separation distance at 30 mm HAB, and decreases the mean fringe tortuosity both of 15 mm and 30 mm HAB based on the results from high-resolution transmission electron microscope (HRTEM). Meanwhile, the ratio of I D1 /I G , I D3 /I G , and I D4 /I G has been used to evaluate the degree of graphitization, it indicates that the use of ammonia increases the degree of graphitization, but both of the hybridization degree of sp3 and sp2 in amorphous carbon and carbon atoms decrease. Furthermore, the proportion of oxygenated functional groups decreases with the increase of ammonia. The highest content of C-OH functional group is about 9 % to 15 %, followed by C=O and O-C=O functional groups, which is about 3 % to 6 % and 2.5 % to 3.5 %, respectively. Eventually, the oxidation process of the particles has been analyzed, it is indicated that the use of ammonia decreases the oxidation activity, which is more difficult to oxidize. [ABSTRACT FROM AUTHOR]

Grafting carbon nanotubes (CNTs) is one of the most commonly used methods for modifying carbon fiber surface, during which complex device is usually needed and the growth of CNTs is difficult to control. Herein, we provide an implementable and continuous chemical vapor deposition (CVD) process, by which the novel multiscale reinforcement of carbon nanotube (CNT)-grafted carbon fiber is prepared. After exploring the effects of the moving speed and growth atmosphere on the morphology and mechanical properties of carbon nanotubes/carbon fiber (CNTs/CF) reinforcement, the optimal CVD process conditions are determined. The results show that low moving speeds of carbon fibers passing through the reactor can prolong the growth time of CNTs, increasing the thickness and density of the CNTs layer. When the moving speed is 3 cm/min or 4 cm/min, the surface graphitization degree and tensile strength of CNTs/CF almost simultaneously reach the highest value. It is also found that H2 in the growth atmosphere can inhibit the cracking of C2H2 and has a certain effect on prolonging the life of the catalyst. Meanwhile, the graphitization degree is promoted gradually with the increase in H2 flow rate from 0 to 0.9 L/min, which is beneficial to CNTs/CF tensile properties. [ABSTRACT FROM AUTHOR]

Supercapacitors are promising for high power application in the recent years. In particular, the conversion of simple and available carbon materials into economic and high performance electrical devices receives excellent scientific and technological interest. This paper reports a one-step strategy for synthesizing hierarchical porous carbon derived from phenolic resin (PR), which is then used to configure electric double-layer capacitors (EDLCs). Here, a carbon material with a flexible porous structure, large specific surface area, and high graphitization degree is prepared using potassium ferrate (K 2 FeO 4) to catalytically activate PR and to realize synchronous carbonization and graphitization. This method overcomes the disadvantage of time-consuming, high-cost, and environmentally unfriendly. In addition, the as-prepared carbon material has a high specific surface area (1086 m2 g−1) and a large pore size (3.07 nm), which can increase the transfer rate of electrolyte ions. The specific capacitance of the obtained electrode material is 315 F g−1 at 1.0 A g−1, and the optimized electrode material has an ultra-long cycle lifetime (capacitance retention rate is 96.3% after 10,000 cycles). Thus, the hierarchically Fe-doped porous carbon material derived from PR material is expected to realize high rate capacitance for supercapacitor applications. [ABSTRACT FROM AUTHOR]

This work examined the effects of CO 2 gasification in the reduction layer on NO emissions during subsequent char combustion in the oxidation layer during a grate-fired process. In experimental trials, the pyrolysis char of Shenhua bituminous coal was initially gasified in CO 2 , employing different conversion rates so as to vary the residence time of the char in the reduction layer. The pore structure and degree of graphitization of the char were monitored and the effects of CO 2 gasification on NO emissions were ascertained. In this manner, the relationship between the transformation of char nitrogen and the physicochemical characteristics of the char was clarified. The effects of CO 2 gasification on the properties of the char and NO emissions in the subsequent oxidation layer were determined. The results show that CO 2 gasification can improve the pore structure and degree of graphitization of the char, such that NO emissions are reduced in an inert atmosphere. However, the conversion rate of char nitrogen will increase in conjunction with oxidative combustion. • Pyrolysis-gasified char is more accurate for research than pyrolysis char. • CO 2 gasification can improve the pore structure of char. • The improvement of the pore structure is beneficial to char reducing nitric oxide. • CO 2 gasification can increase the graphitization degree of char. • The increase of the graphitization degree will increase nitric oxide emissions. [ABSTRACT FROM AUTHOR]

In this study, the surface functional groups types and concentrations, graphitization degree, and oxidation reactivity of exhaust soot samples generated by a heavy-duty engine when employing neat diesel and four base oil dosed mixtures as the fuel was compared. Fourier transform infrared (FTIR), Raman spectroscopy and Thermal gravimetric analyzer (TGA) were used to characterize particle physicochemical properties. Four lubricating base oils were blended in diesel at a mass ratio of 0.5% and 1.0% for combustion. It was found that although the chemical compositions of these four base oils were different, the aliphatic C H functional groups content, graphitization degree and oxidation reactivity of exhaust soot exhibited similar trends. The combustion of base oil was found to change the graphitization degree of emitted soot and lead to soot with a more disordered nanostructure. The soot particles derived from base oil blended fuels had higher aliphatic C H groups concentration than those from neat diesel. Soot oxidation reactivity analyses showed that soot generated from base oil blended fuels had lower characteristic temperatures and lower activation energy than that from neat diesel. Besides, there was a clear correlation between the soot graphitization degree, relative concentration of aliphatic C H groups and its oxidation reactivity. [ABSTRACT FROM AUTHOR]

Summary: In this paper, polyacrylonitrile‐based graphite felt (GF), carbon felt (CF) and the effect of thermal activation on them with or without the catalyst (BiCl3) are comprehensively investigated for iron‐chromium redox flow battery (ICRFB) application. The physical‐chemical parameters of GF and CF after the thermal activation is affected significantly by their graphitization degree, oxygen functional groups, and surface area. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results manifest that GF and CF before and after the thermal activation have different electrocatalytic activities owing to oxygen functional groups number increase and the graphitization degree decrease. In terms of the capacity decay rate, as oxygen functional groups provide shorter electrocatalytic pathways than bismuth ions, the performance of GF and CF after the thermal activation is more ideal. As a result, GF before and after the thermal activation exhibits higher efficiency (EE: 86%) and better stability at a charge‐discharge current density of 60 mA·cm−2 than those of CF during charge‐discharge cycling, as the dominant limitation in an ICRFB is ohmic and activation polarization. Therefore, GF after thermal activation together with the addition of BiCl3 in the electrolyte is a more promising electrode material for ICRFBs application than CF. [ABSTRACT FROM AUTHOR]

Nickel/scandia-ceria-stabilized-zirconia (Ni/10Sc1CeSZ) cermet is a potential anode for solid oxide fuel cells. The anode powder is prepared through a microwave-assisted glycine nitrate combustion process, and its properties, including phase and chemical composition as well as morphology, are characterized by XRD, TEM, and EDS techniques. The electrical conductivity and electrochemical behavior under low concentration of dry hydrogen (H2:N2 volume ratio = 10:90) and dry methane (CH4:N2 volume ratio = 50:50) fuels are determined. XRD results show two phases, namely, cubic NiO phase and cubic 10Sc1CeSZ phase, with the crystallite sizes of 67 and 40 nm, respectively. The area specific resistances (ASRs) of the prepared anode measured using a symmetrical cell of Ni/10Sc1CeSZ|10Sc1CeSZ|Ni/10Sc1CeSZ are 0.96 and 24.3 Ω cm2 observed at 800 °C in dry low hydrogen concentration (10 vol% hydrogen–90 vol% nitrogen) and dry methane (50 vol% methane–50 vol% nitrogen) fuels, respectively. The ASR in methane fuel is higher than that in hydrogen fuel at all operating temperatures (600–800 °C) because of carbon deposition. The amount of deposited carbon and degree of graphitization (IG/ID) of this anode after exposure in methane at 800 °C for 3 h are 4.34% and 2.1, respectively. Overall, Ni/10Sc1CeSZ cermet synthesized by glycine nitrate process assisted with microwave-heating technique exhibits acceptable electrochemical behavior even at low hydrogen concentration and also in dry methane. This can be related to the improved powder morphology as a result of uniform heating assisted by microwave energy. [ABSTRACT FROM AUTHOR]

Converting greenhouse gas CO 2 into high-performance energy storage materials is of great significance due to its capability of simultaneously addressing environmental issues and energy crises. However, great challenges still remain for the low-carbon and energy-efficient conversion of CO 2. Herein, we report an energy-efficient and time-saving strategy for converting CO 2 into carbon materials by the reaction of CO 2 with Mg(AlH 4) 2 at about 126–136 ℃ in seconds. The chemical reaction of CO 2 with Mg(AlH 4) 2 is reported for the first time. Importantly, the graphitization degree and pore structure of as-synthesized carbon materials are found to be regulated by CO 2 pressure. As a lithium storage application, the graphitization degree-dependent electrochemical performance is revealed for the carbon anodes. The highly graphitized carbon prepared at high CO 2 pressure exhibits high capacity and ultra-long cycle life, delivering a high reversible capacity of 487 mAh g−1 at 1.0 A g−1 after 3500 cycles. This study develops a green and low-temperature strategy to synthesize CO 2 -derived carbon materials with tunable graphitization degree for energy storage. • Carbon material is prepared by the first reported reaction of CO 2 with Mg(AlH 4) 2. • The graphitization degree of the carbon material can be regulated by CO 2 pressure. • The graphitization degree-dependent electrochemical performance is revealed for carbon. • The highly graphitized carbon exhibits a high capacity and ultra-long cycle life. [ABSTRACT FROM AUTHOR]

Mesophase pitch-based carbon fibers (MPCFs) with various concentration of boron were fabricated through an easy and effective strategy by treating stabilized fibers with boron acid solution. The microstructural evolution of boron-doped MPCFs was characterized. It was found that boron doping promoted high degree of graphitization with the decrease of interlayer spacing and the growth of crystallite dimension due to catalytic graphitization of boron to carbon. Boron doping significantly improved 5 wt% burn-off temperature of MPCFs increasing by 344 °C, and the tensile strength of MPCFs was also enhanced by 19%. Both of the outstanding oxidation resistance and mechanical performance of MPCFs was obtained due to effect of boron. The results demonstrated boron doping was a feasible way to produce high-performance MPCFs. [ABSTRACT FROM AUTHOR]

Abstract Carbon/carbon-boron nitride (C/C-BN) composites were manufactured by adding hexagonal boron nitride (h-BN) powders into carbon fiber preform and a subsequent chemical vapor infiltration (CVI) process for deposition of pyrolytic carbon (PyC). Microstructure and oxidation behavior of carbon/carbon composites with 9 vol% h-BN (C/C-BN9) were studied in comparison to carbon/carbon (C/C) composites. Results showed that with the addition of h-BN powders, a regenerative laminar (ReL) PyC with higher texture was achieved. Note that the introduction of h-BN powder make great contributes to graphitization degree of PyC, leading to larger oxidation activation energy. Moreover, under an air atmosphere, h-BN started to oxidize above 800 °C, and generated molten boron oxide (B 2 O 3) which prohibited oxygen diffusion by filling in pores, cracks and other defects. As these reasons mentioned above, after oxidation tests under an air atmosphere, mass losses of C/C-BN9 composites were lower than that of C/C composites at all test temperatures (600–900 °C), indicating that the oxidation resistance of C/C-BN9 composites is better than that of C/C composites. [ABSTRACT FROM AUTHOR]

Highlights • The residual char graphization degree influences ash fusion behavior. • The high graphization degree of char hinders the carbothermal reaction. • The peak temperatures of carbothermal reaction increase with graphitization. • The residual char benefits the formation of FeSi, also increases AFTs. Abstract Residual char is widely found in the slag from gasifier, which significantly influences the ash fusibility due to carbothermal reaction. Residual char has different graphitization degree owing to the residence time and operating temperature of the gasifier, while the effect of graphitization degree of residual char on ash fusibility and carbothermal reaction is still unknown. In this work, graphite, activated carbon and high temperature demineralized coal char were selected to investigate the effect of graphitization degree of residual char on ash fusibility under an Ar atmosphere. X-ray diffraction (XRD) and Siroquant software were used to investigate the mineral transformation of the ashes with residual char at high temperatures. Thermogravimetric combined with mass spectrum and differential thermal analysis (TG-MS-DSC) were used to study the effect of graphitization degree of residual char on mineral and carbothermal reaction during heating. When the ash contains same content of residual char, the ash fusion temperatures (AFTs) increase as the graphitization degree of residual char increases. The influence by residual char is more obvious when the mass fraction exceeds 5%. The increase of graphitization degree of residual char impedes the mineral reaction and the carbothermal reaction. The initial temperature of the mineral reaction increases from 1229.3 °C to 1247.2 °C and 1260.4 °C for the ashes with activated carbon, coal char, and graphite, respectively. The peak temperatures of the carbothermal reaction are 1306, 1319 and 1339 °C. At the temperature below 1300 °C, the increase of AFTs is attributed to the increase in the content of cristobalite, and the decrease in the content of anorthite. Above 1300 °C, the increase of AFTs is caused by the increase of the amount of unreacted residual char. Besides, the residual char benefits the formation of FeSi, which also leads to increases of the AFTs. [ABSTRACT FROM AUTHOR]

The effect of pyrolysis temperature on biochar properties is more exacerbated when combined with the presence of metallic dopants on the surface of the lignocellulosic material. Herein, we investigate the relationship between the surface composition (SC), the graphitization degree (GD), the particle size (PS) and the catalytic activity of mandarin peel biochar decorated with copper and nickel alloy. All biochar samples were prepared by a wet impregnation of the metal ions followed by slow pyrolysis of the Cu2+/Ni2+-loaded biomass at temperatures ranging from 300° to 700 °C, for 15 min and under N 2 atmosphere. Interestingly, the biochar with the highest GD was obtained at 300 °C; its surface contained CuNi alloy and NiO, whereas it contained only the bimetallic alloy for all samples fabricated at 500 and 700 °C. The 300 °C and 500 °C samples have mean PSs in the nanoscale regime, 71 ± 12 nm and 54 ± 12 nm, respectively. On contrast, the 700 °C biochar composites have very broad PS distributions in the 30–400 nm size range. They were also found to be the least graphitized samples. Practically, the 300 °C nanocomposite was the most active catalyst for the oxidative degradation of Methylene Blue, chosen as a model reaction for the catalytic performance testing. The degradation was total under H 2 O 2 conditions, and the kinetic experimental data fitted the pseudo-first-order with degradation apparent constant 0.071 min-1. Despite its lowest mean particle size and graphitization degree, higher than the graphitization degrees of the 700 °C nanocomposites, the sample elaborated at 500 °C was the least active catalyst. Its highest K to C atomic ratio suggests that potassium emerging from the biochar surface had a poisoning effect which deactivated the CuNi alloy. Conclusively, these findings permitted to gain more insights into the synergistic effects of surface composition, particle size and graphitization degree on the catalytic activity of Biochar-supported CuNi alloy elaborated at different pyrolysis temperatures. ● CuNi alloy coated mandarin peel biochars were prepared for Fenton-like reaction. ● The 300 °C sample had NiO and CuNi alloy decorating the biochar surface. ● The NiO presence provided more O 2 vacancies which boosted the catalytic activity. ● The 300 °C sample was the most active catalyst with the lowest D to G ratio. ● The K to C atomic ratio outweighed graphitization state and particle size effects. [ABSTRACT FROM AUTHOR]

The objective of this study was to use a statistical approach to determine the correlation of fixed carbon, volatile matters and moisture with the specific electrical consumption and exergy efficiency by collecting and analyzing an abundance of actual production data generated in silicon plants during the melting process of silicon produced in the submerged arc furnace (SAF). A high positive correlation (the r maximum value of 0.82) between the fixed carbon composition and the specific electrical consumption, as well as the perfect negative correlation (the r maximum value of −0.92) between the fixed carbon and the exergy efficiency were found, especially when the carbon materials contained a very high amount of graphitized carbon. Compared with the carbon materials without woodchips, the high correlation among the volatile matters, the specific electrical consumption and exergy efficiency was observed when using the carbon materials with woodchips. The influence of the proximate composition on the electrical consumption and exergy efficiency becomes stronger with the increase of the graphitized carbon content in the carbon materials. The analysis results can be used to support decisions when optimizing the proximate composition of the carbonaceous reductants in order to increase exergy efficiency and decrease electrical consumption costs, which is one of the biggest operating costs in the silicon furnace. [ABSTRACT FROM AUTHOR]

Nanocarbons (e.g. graphene, carbon nanotubes, ordered mesoporous carbon, carbon nanofiber, etc.) are widely regarded as promising platforms for developing novel catalytic composites. These catalytic nanocarbon composites have performed exceptionally well in various catalysis processes including chemical catalysis, photocatalysis, and electrocatalysis. This is contributed by their unique intrinsic and extrinsic properties such as high graphitization degree, versatile surface chemistry, and novel morphology. In this review, we provide a short overview on the recent status of the nanocarbons used for preparing various novel catalytic composites. The criteria for developing a high performance nanocarbon composites are assessed and the challenges are critically identified. Finally, we discuss potential future research directions in this field which include developing robust fabrication methodologies, improving the interface and charge transfer, improving the durablity of the catalyst, minimizing the environmental impact, and investigation by advanced characterization methods and modelling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Green and facile α-FeOOH/GBC Fenton-like systems were constructed to remove OTC. • The performance of α-FeOOH/GBC enhanced with the increase of GBC's graphitization. • The major role of GBC was to facilitate the reaction between H 2 O 2 and Fe(III). • Donated eletrons for fasting Fe(III)/Fe(II) redox cycle was another role of GBC. • O 2 - and 1O 2 were identified as the predominant ROS for OTC degradation. Due to the contradiction between attractive properties and undesirable Fenton-like catalytic performance of iron minerals, how to enhance their Fenton-like catalytic activity is a critical but challenging issue. Here, we took an eco-friendly approach to improve the Fenton-like catalytic capacity of goethite (α-FeOOH) by loading it on graphitized biochar (GBC), and the results indicated that the existence of GBC could successfully facilitate the oxytetracycline (OTC) removal. The degradation rate constant of α-FeOOH/GBC-10 composite was approximately 2.1 times higher than that of α-FeOOH. GBCs with different graphitization degrees were obtained by adjusting the pyrolysis temperature. Interestingly, the improvement of catalytic activity of α-FeOOH/GBC was well correlated with the graphitization degree of GBC, and the graphitized structures (sp2-C) and functional group (C O) in GBC could expedite the blocked Fe(III)/Fe(II) cycling by speeding up the electrons transfer from H 2 O 2 to α-FeOOH and donating electrons to Fe(III). In addition, the electron spin resonance and quenching experiments demonstrated that OTC removal was attributed to the joint action of •OH, O 2 −, and 1O 2. This study sheds light on the possible role of GBC in Fenton-like reactions based on iron minerals and thus, lays the groundwork for the rational construction of more efficient Fenton-like catalytic systems. [ABSTRACT FROM AUTHOR]

In this study, comparative experiments were conducted on the adsorption of cationic blue onto graphene oxides (GOs) synthesized by graphites with various graphitization degrees. XRD, XPS, FT-IR, Raman, AFM and BET were used to characterize the prepared GOs. The results demonstrated that graphites with lower graphitization degrees were more easily oxidized, and GOs prepared from those graphites had more oxygen-containing groups, higher degrees of defects, thinner layers and higher specific surface areas. The equilibrium data was in better agreement with the Langmuir model than both the Freundlich model and the Temkin model. In addition, the adsorption of cationic blue on the GOs was well-described by the pseudo-second order kinetics model according to the kinetic experiments. Moreover, the thermodynamic parameters demonstrated that the adsorption was both an endothermic and spontaneous process. [ABSTRACT FROM AUTHOR]

A series of mesoporous Ni/TiO 2 catalysts with different loadings of nickel from 10 to 50 wt% was successfully prepared via a facile one-pot sol–gel route; characterized for its structural, textural and redox properties; and tested for the non-oxidative thermocatalytic decomposition of undiluted methane for the first time. The characterization results reveal the presence of both NiO and NiTiO 3 and metallic nickel as active metal phase in the fresh and reduced catalysts, respectively. Spherical catalyst particles were found to be highly inter-aggregated and to provide a porous texture to the catalyst. All of the prepared catalysts exhibited high catalytic activity and stability for methane decomposition. It is due to the fine dispersion of active nickel nanoparticles on the surface of the TiO 2 support with proper metal-support interaction. Moreover, with increasing nickel loading and reaction temperature, the yields of hydrogen and nanocarbon were found to be significantly increased. A maximum hydrogen yield of 56% and a final carbon yield of 1544% were obtained for the 50% Ni/TiO 2 catalyst at 700 °C with an undiluted methane feed of 150 ml/min for 360 min of time on stream. The catalyst showed high catalyst stability, for a period of 960 min of time on stream and ∼24% hydrogen yield was observed at the end of long-term run using the 50% Ni/TiO 2 catalyst. Moreover, irrespective of the nickel loading involved, bulk amount of multiwalled carbon nanotubes were deposited on the surface of the catalyst. XRD and Raman analyses of the spent catalysts showed that the crystallinity of nanocarbon increased with increasing nickel loadings, whereas the graphitization degree remained unaffected, with an I D /I G value of 0.88. [ABSTRACT FROM AUTHOR]

It is of great interest to develop metal-free electrocatalysts derived from cheap and environmental friendly biomass for oxygen reduction reaction (ORR). Here we report a facile method to prepare graphene-like N-doped carbons with a high degree of graphitization and large surface area using chitosan as precursor and FeCl 3 as soft template. The graphitization degree, surface area and the N species can be simply adjusted by controlling the annealing temperature. The soft template induced sample annealed at 800 °C (STS800) exhibits more positive onset potential than the samples annealed at 600 °C and 1000 °C (−0.08 V compared to −0.12 V and −0.15 V), which demonstrates that all of the high degree of graphitization, large surface area and the high percentages of pyridinic-N and graphitic-N play curial roles in the good ORR activity. The value of onset potential for STS800 is just 25 mV negative than that for Pt/C (−0.08 V to −0.055 V) and the ORR current density at merely −0.3 V for STS800 (−2.16 mA cm −2 ) is larger than that for Pt/C (−2.12 mA cm −2 ), which indicates its superior ORR activity even compared to Pt/C. Besides, the current for STS800 retains 95% at −0.2 V in 30000 s while that for Pt/C just retains 88%, which reveals its longer durability. With the addition of 3 M methanol, the CV curve of STS800 shows no noticeable current attenuation, indicating its good methanol tolerance. The excellent ORR activity, good methanol tolerance, and long durability demonstrate that STS800 could be a promising alternative for costly Pt-based electrocatalysts. [ABSTRACT FROM AUTHOR]

• Multi-color phosphorescent CDs were prepared. • These phosphorescent CDs accelerated the production of 1O 2. • Graphitization degrees and amounts of C O on RTP were first elucidated. • The proposed multi-color CDs showed the application of LED lamps. Room-temperature phosphorescence with multiple-color activated the widespread interest owing to their promising applications, howbeit, there still exist the insurmountable challenge, especially for elucidating their photoluminescence mechanism and tunable emissions. Here we systematically proposed several carbon dots (CDs) with different degrees of graphitization and amounts of carbonyl while sulfuric acid and ethanol played the critical roles. In brief, sulfuric acid functioned as the carbonization and strong oxidization reagent, while the increasing volumes of ethanol gradually reduced the boiling point of the reactions. Significantly, the energy of these phosphorescent CDs transferred from their excited triplets to oxygen molecules once they were irradiated by UV in aqueous, resulting in the production of the singlet oxygen to oxidize 3,3′,5,5′-tetramethylbenzidine. This finding indirectly provided the evidence for the existence of the phosphorescence rather than delayed fluorescence. Towards the photoluminescence mechanism, their fluorescence of CDs was originated from π-π* transition of C C in the carbon cores and n-π* transition of C O on the surfaces, while RTP was mainly attributed to n-π* transition of the carbonyls. The further evidence suggested that the CDs with different graphitization degrees and amounts of C O regulated their multiple-color phosphorescence. Besides, we employed these CDs for information encryption and preparing LED lamps. [ABSTRACT FROM AUTHOR]

Effects of viscosity index improver on morphology and graphitization degree of diesel particulate matter were investigated. Three lubricating oils with different viscosity were tested and compared in a two cylinder, four stroke, direct injection diesel engine. 5.0 wt. % and 10 wt. % viscosity index improver were added into lubricating oil to improve the viscosity-temperature performance respectively. Transmission Electron Microscope and Raman spectroscopy were employed to analyze the primary particle size distribution and graphitization degree of diesel particles from different lubricating oils. The primary particles size distribution conformed to Gaussian distribution. When the higher viscosity lubricating oil was used, the primary particle boundaries tend to be clearer and the mean diameter is smaller at 1600 rpm and 2200 rpm. As to the graphitization degree, the ratio of the D 1 band to G band areas (A D1 /A G ) increased with the increasing viscosity at 1600 rpm and 2200 rpm, indicating that the graphitization degree was lower when the higher viscosity lubricating oil was used. [ABSTRACT FROM AUTHOR]

Iron oxide/carbon nanofibers (FeO x /CNFs) were prepared by electrospinning FeCl 3 ·6H 2 O-polyacrylonitrile (PAN) precursors and heat treating at 400, 600, 800, 1000 °C. As carbonization temperature increased, granular FeO x gradually migrated from nanofiber interior with effectual contacts between electrolyte and active materials rising at first and then falling; Oxidation states of iron in FeO x /CNFs changed from Fe 2 O 3 to FeO and Fe with an improvement of capacity retention and an extra reversible capacity catalyzed by Fe; Graphitization process of carbon matrices proceed with less defective structures and heteroatom contents, leading to an increase of conductivity and a diminution of irreversible reactions during cycling. As systematically studied and compared in electrochemical performance, FeO x /CNFs with FeO, Fe state, highly graphitized carbon matrices and migration structure with FeO and Fe both embedded in and dispersed on carbon matrices presented stable cycling performance with a reversible capacity of ∼674 mAhg −1 after 60 cycles and outstanding rate capability. The above trade-off study of all the cooperative factors that affected the electrochemical property might make an effective guidance for preparation of promising FeO x /CNF anodes. [ABSTRACT FROM AUTHOR]

The porous carbon is considered to be one of the most suitable materials for volatile organic compounds (VOCs) adsorption and separation. Revealing the adsorption behavior and molecular interaction mechanism is of great significance for the preparation and synthesis of porous carbon adsorbents. Herein, we investigated detailed mechanistic effects of graphitization degrees and surface oxygen heteroatoms of porous carbon on their benzene and ethanol adsorptive separation performance by combining experiments and theoretical calculations. The results show that graphitized carbon surface has a stronger van der Waals interaction with benzene molecules compared to the disordered carbon surface, and thus exhibit a higher benzene adsorption performance and benzene/ethanol selectivity. While the introduction of oxygen functional groups enhances electrostatic affinity of porous carbon surface, resulting in higher ethanol adsorption capacity and ethanol/benzene selectivity under the entire pressure range. Subsequent theoretical calculations studied the adsorption behaviors of benzene and ethanol molecules in porous carbon models (with different graphitization degrees and oxygen contents) from the perspective of the weak interactions, and found the different molecular configurations of benzene and ethanol is the main leading cause of their different adsorption preferences. This study provided mechanistic insights on how the graphitization degrees and oxygen heteroatoms affected the capture and separation properties of porous carbon, which would further provide a rational alternative strategy in the preparation and synthesis of porous carbons for the effective gas mixture capture and separation. • The vital role of graphitization degrees and surface oxygen heteroatoms on VOCs adsorptive separation is proved. • Provide a molecular perspective on the adsorption behavior of VOCs in porous carbons. • The intrinsic enhancement mechanism in adsorption and separation process was clarified. • Provide a rational alternative strategy in preparation and synthesis of porous carbons. [ABSTRACT FROM AUTHOR]