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MOFs (Metal organic frameworks) derivatives represented by quasi-MOFs have excellent physical and chemical properties and can be applied for the catalytic combustion of VOCs. In this work, Pd/quasi-Ce-BTC synthesized by simple one-step N2 pyrolysis was applied to the oxidation of toluene, showing excellent toluene catalytic activity (T90=175 °C, 30000 mL/(g·h)). Microscopic analyses indicate the formation and interaction of a carbon matrix composite quasi-MOF structure interface. The results show that the amorphous carbon matrix formed during the partial pyrolysis of Ce-BTC significantly improves the adsorption and activation capacity of toluene in the reaction, and constructes a reductive system to maintain high concentrations of Ce3+ and Pd0, which can facilitate the activation and utilization of oxygen in reaction. Quasi in-situ XPS proves that carbon matrix is indirectly involved in the activation and storage of oxygen, and Pd0 is the crucial active site for the activation of oxygen. Stability and water resistance tests display good stability of Pd/quasi-Ce-BTC. This work provides a potential method for designing quasi-MOF catalysts towards VOCs effective abatement.

Nanoporous materials show a promising combination of mechanical properties in terms of their relative density; while there are numerous studies based on metallic nanoporous materials, here we focus on amorphous carbon with a bicontinuous nanoporous structure as an alternative to control the mechanical properties for the function of filament composition.Using atomistic simulations, we study the mechanical response of nanoporous amorphous carbon with 50% porosity, with sp3 content ranging from 10% to 50%. Our results show an unusually high strength between 10 and 20 GPa as a function of the %sp3 content. We present an analytical analysis derived from the Gibson–Ashby model for porous solids, and from the He and Thorpe theory for covalent solids to describe Young’s modulus and yield strength scaling laws extremely well, revealing also that the high strength is mainly due to the presence of sp3 bonding. Alternatively, we also find two distinct fracture modes: for low %sp3 samples, we observe a ductile-type behavior, while high %sp3 leads to brittle-type behavior due to high high shear strain clusters driving the carbon bond breaking that finally promotes the filament fracture. All in all, nanoporous amorphous carbon with bicontinuous structure is presented as a lightweight material with a tunable elasto-plastic response in terms of porosity and sp3 bonding, resulting in a material with a broad range of possible combinations of mechanical properties.

Thin and ultrathin carbon films reduce the laser energy required for copper powder fusion in selective laser melting (SLM). The low absorption of infrared (IR) radiation and its excellent thermal conductivity leads to an intricate combination of processing parameters to obtain high-quality printed parts in SLM. Two carbon-based sacrificial thin films were deposited onto copper to facilitate light absorption into the copper substrates. Graphite-like (3.5 µm) and ultra-thin (25 nm) amorphous carbon films were deposited by aerosol spraying and direct current magnetron sputtering, respectively. The melting was analyzed for several IR (1.06 µm) laser powers in order to observe the coating influence on the energy absorption. Scanning electron microscopy showed the topography and cross-section of the thermally affected area, electron backscatter diffraction provided the surface chemical composition of the films, and glow-discharge optical emission spectroscopy (GDOES) allowed the tracking of the in-deep chemical composition of the 3D printed parts using carbon film-covered copper. Ultra-thin films of a few tens of nanometers could reduce fusion energy by about 40%, enhanced by interferences phenomena. Despite the lower energy required, the melting maintained good quality and high wettability when using top carbon coatings. A copper part was SLM printed and associated with 25 nm of carbon deposition between two copper layers. The chemical composition analysis demonstrated that the carbon was intrinsically removed during the fusion process, preserving the high purity of the copper part.

Replacing the conventional carbonate electrolyte by solid-state electrolyte (SSE) will offer improved safety for lithium-ion batteries. To further improve the energy density, Silicon (Si) is attractive for next generation solid-state battery (SSB) because of its high specific capacity and low cost. High energy density and safe Si-based SSB, however, is plagued by large volume change that leads to poor mechanical stability and slow lithium ions transportation at the multiple interfaces between Si and SSE. Herein, we designed a self-integrated and monolithic Si/two dimensional layered T3C2Tx (MXene, Tx stands for terminal functional groups) electrode architecture with interfacial nitrogen engineering. During a heat treatment process, the polyacrylonitrile not only converts into amorphous carbon (a-C) that shells Si but also forms robust interfacial nitrogen chemical bonds that anchors Si and MXene. During repeated lithiation and delithiation processes, the robust interfacial engineered Si/MXene configuration enhances the mechanical adhesion between Si and MXene that improves the structure stability but also contributes to form stable solid-electrolyte interphase (SEI). In addition, the N-MXene provides fast lithium ions transportation pathways. Consequently, the Si/MXene with interfacial nitrogen engineering (denoted as Si-N-MXene) deliveres high-rate performance with a specific capacity of 1498 mAh g−1 at a high current of 6.4 A g−1. A Si-N-MXene/NMC full cell exhibited a capacity retention of 80.5% after 200 cycles. The Si-N-MXene electrode is also applied to SSB and shows a relative stable cycling over 100 cycles, demonstrating the versatility of this concept.

Aluminum oxynitride (AlON) powders were synthesized by a novel carbothermal reduction and nitridation (CRN) method. Homogenous and fluffy AlOOH/C core-shell nanoparticle precursor was hydrothermally synthesized with aluminum nitrate hydrate, sucrose and urea as starting materials. Then single-phase AlON powders were synthesized by CRN method at 1700 °C for 2 h. The phase transition and growth of Al2O3 particles was effectively retarded by the amorphous carbon nano-layers on the surface of precursor, resulting in significantly lower reaction temperature and further smaller particle size. Based on above fine AlON raw material, transparent AlON ceramic was prepared by pressureless sintering at 1880 ℃ with the in-line transmittance above 80 %.

Amosic-3 SiC/SiC composites were irradiated at 300 °C using 6 MeV Si ions to peak doses of 13 and 55 displacements per atom (dpa). The loss of amorphous carbon packets and the growth of SiC grains were simultaneously observed in Amosic-3 SiC fibers, using a combination of transmission electron microscopy (TEM) and Raman spectroscopy. A mechanism based on the grain growth theory was proposed to expound the relationship between the loss of carbon packets and the growth of SiC grains. Small and curved SiC grains can absorb surrounding carbon packets to grow themselves; at some point, these grains further grow at the expense of adjacent small SiC grains until their grain boundary became straight. TEM images were found to support the above mechanism.

Hypothesis Wetting characterization and the production of engineered surfaces showing distinct contact angles or spreading behavior is of major importance for many industrial and scientific applications. As chemical composition plays a major role in the wetting behavior of flat samples, wettability, capillary forces and resulting droplet spreading on anisotropic surface patterns are expected to be highly dependent on surface chemistry as well. Experiments To gain understanding of the fundamental principles of the interplay between surface topography and surface chemistry regarding water wettability, anisotropic line patterns were produced on steel samples in a direct laser writing process. Homogeneous surface coatings allowed for a chemical masking of the laser patterns and therewith the identification of the influence of surface chemistry on static contact angles and wetting anisotropy. Findings While a carbon coating leads to pronounced wettability and spreading along the topographic anisotropy, an inert gold-palladium coating can fully suppress anisotropic droplet spreading. Model calculations show that an amorphous carbon coating leads to Wenzel wetting while the gold-palladium coating causes air inclusions between the water and the surface in the Cassie-Baxter wetting state. Only in combination with the right chemical composition of the surface, directional patterns show their potential of anisotropic wetting behavior.

Electromagnetic wave (EMW) absorbing materials have excellent potential for various applications in civil engineering and the military. In this study, siliconboron carbonitride (SiBCN) ceramics with excellent EMW absorption capability and oxidation resistance were obtained by adjusting the boron content. The results revealed that the graphite crystallite size in the SiBCN ceramics increased from 3.42 to 3.78 nm, whereas the thickness of the oxide layer decreased from 16.6 to 8.2 μm. The highest electrical conductivity and permittivity for the SiBCN ceramics were obtained when the boron content was 5%. The minimum reflection loss was −35.25 dB at 10.57 GHz and a ceramic thickness of 2.0 mm. At a temperature of 600 °C, the SiBCN ceramic exhibited excellent EMW attenuation ability; particularly, the minimum reflection loss reached −29.18 dB at 9.65 GHz and a ceramic thickness of 2.5 mm. The superior EMW absorption properties of the SiBCN ceramics at high temperatures can be ascribed to the synergistic effect of relaxation and conductivity. The results suggest that boron could enhance the transformation of amorphous carbon into crystalline graphite and increase the number of heterointerfaces and conductive paths. This work provides a method for obtaining SiBCN ceramics with excellent EMW absorption properties.

Rechargeable aqueous zinc-ion batteries (AZIBs) that directly use metallic zinc as anode and mildly acidic Zn2+-containing aqueous solutions as electrolytes have exhibited promising complementarity for well-established lithium-ion batteries. The fabrication of high-voltage, high-capacity, and durable cathode and stable anode are the burning issues of fabricating high-performance AZIBs. Herein, the small amount of dual-cation preintercalated and amorphous carbon confined vanadium dioxide (Ni0.006Ca0.0045VO2@C) was prepared for high-performance Zn2+-storage materials, and subsequent in situ electrochemical anodic oxidation strategy was used to convert Ni0.006Ca0.0045VO2@C to δ-(Ni,Ca)V2O5@C as high-capacity AZIB cathode. The elaborate architecture not only showed a high specific capacity of 433.8 mAh g−1 at 0.1 A g−1 but also retained a reversible capacity of 74 mAh g−1 after 4000 cycles at 5 A g−1. In addition, the Zn2+/H+ co-intercalation mechanism was also verified by employing ex situ XRD and ex situ XPS. Finally, the flexible quasi-solid-state ZIBs were also assembled with the Ni0.006Ca0.0045VO2@C as cathode and polyvinyl alcohol hydrogel as electrolyte, suggesting its promising application for the superior Zn2+-storage performance.

Interface protection and kinetics optimization could effectively relieve the shortcomings of bimetallic oxides, such as low conductivity, strong hydrophobicity, insufficient ion diffusion rate and metal interatomic instability. In this work, ultrathin amorphous carbon shells and lattice defects (heteroatoms and vacancies) are introduced into the MnNb2O6 nanofiber surface to improve the electron/ion kinetic stability, conductivity and electrochemical activity. The ultrathin carbon interface protects unstable lattice with defects, thus restraining the adverse reaction between bimetallic oxides and electrolyte. Especially, ultrathin amorphous carbon layer enhances the stability and uniformity of ion transport as the substitute of solid–liquid ion exchange membrane. Lattice defects (N doping and oxygen vacancy) also enhance the ionic kinetics of the material. MnNb2O6 nanofiber, being optimized by interface protection and lattice defects, shows excellent electrochemical performances in Lithium-ion battery and supercapacitor.

In this work, the high temperature friction mechanism of the tetrahedral amorphous carbon (ta-C) film was elucidated. The multilayer ta-C film with alternating hard and soft sub-layers exhibited a low friction coefficient of 0.14 at 400 °C before a sudden failure occurred at 4600 cycles. The wear failure was attributed to the gradual consumption of the ta-C film at the contact region. The design of a hard or soft top layer effectively regulated the high temperature friction properties of the multilayer ta-C. The addition of a hard top layer contributed to a low friction coefficient (0.11) and a minor wear rate (4.0 × 10−7 mm3/(N m)), while a soft top layer deteriorated the lubrication effect. It was proposed that the passivation of dangling bonds at the sliding interface dominated the low-friction mechanism of the ta-C film at high temperature, while the friction induced graphitization and the formation of sp2-rich carbonaceous transfer layer triggered C C inter-film bonding, resulting in serious adhesion force and lubrication failure. Moreover, the multilayer ta-C film with hard top layer obtained excellent friction performance within 500 °C, while the high temperature induced oxidation and volatilization of carbon atoms led to the wear failure at 600 °C.

The paper presents a low-temperature method for the synthesis of tungsten boride containing ultra-fine powders of boron carbide matrix ceramics constituting an important class of superhard materials with diversity of industrial applications. Wet chemical method was used to prepare preceramic precursors. The technique provides annealing of a viscous paste of the mixture of ammonium paratungstate–zirconium(IV) oxide–cobalt acetate tetrahydrate–sucrose–amorphous boron at 200 °C in air and then at 600 °C in argon atmosphere for 2 h with the further grinding and additional annealing of the obtained powders at 800–1500 °C. Hot pressing of the complex ceramic powders at 1000–1700 °C was realized by using the SPS method. It was established that at 600 °C there were formed WO3–x, Co3O4, CoO, and amorphous carbon. The XRD data confirmed low temperature (800–1000 °C) formation of WC–Co, ZrB2, B4C, and W2B5. Tungsten carbide was completely converted into tungsten boride. Structural-morphological characteristics of the obtained samples were studied by using the SEM.

Laser-induced graphene (LIG) technology featuring low-cost, high-efficiency and scalability has presented great advantages in micro-supercapacitors (MSCs) fabrication. However, the limited capacitance of LIG based MSCs is still hindering their further development. Herein, we introduce joule heating as a critical in-situ treatment merged with the assembly of laser-induced graphene paper based MSCs (LIGP-MSCs) toward capacitive enhancement. By increasing heating-treatment temperature from ∼20 to 500 °C, the number of nanopores in LIGP continuously increases, attributed to the gradual decomposition of amorphous carbon components. The resulting joule-heated LIGP (J-LIGP) with improved specific surface area (160.97–533.49 m2/g) and pore volume (0.179–0.553 cm3/g) as well as superhydrophilic surface is highly suitable to be employed as J-LIGP-MSCs microelectrodes. By investigating process dependent performance, the J-LIGP-MSCs heated at 500 °C for 60 min delivers a significantly improved specific areal capacitance (CA) of 13.71 mF/cm2 at 10 mV/s, which is approximately six-fold higher than that of unheated LIGP-MSCs. By further exploring and optimizing the process efficiency, J-LIGP-MSCs with a CA of 12.61 mF/cm2 has been achieved by 550 °C heating for only 5 min. Along with superior mechanical flexibility, cyclability and structural modularity, the proposed in-situ joule heating treatment is finally proved to be a universal approach for consistently enhancing the CA of LIG based MSCs processed under various chemical modifications.

Interatomic potentials based on neural-network machine learning method have attracted considerable attention in recent years owing to their outstanding ability to balance the accuracy and efficiency in atomistic simulations. In this work, a neural-network potential (NNP) for carbon is generated to simulate the structural properties of various carbon structures. The potential is trained using a database consisting of crystalline and liquid structures obtained by the first-principles density functional theory (DFT) calculations. The developed potential accurately predicts the energies and forces in crystalline and liquid carbon structures, the energetic stability of defected graphene, and the structures of amorphous carbon as the function of density. The excellent accuracy and transferability of the NNP provide a promising tool for accurate atomistic simulations of various carbon materials with faster speed and much lower cost.

Porous SiOC ceramics were prepared with tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) as sol−gel precursors, and followed by etching with HF and NaOH solution. The microstructure evolution and chemical etching as a function of pyrolysis temperature were investigated. The amorphous carbon increases as rising the temperature from 800 oC to 1200 oC, and the graphitic carbon increases with further etching by HF and NaOH. However, the effect of pyrolysis temperature on the structure of C is more significant. The hydroxylation reaction and phase separation of SiOC ceramics results in the increase of SiO4 unit, which reacts with HF and NaOH to form micro- and mesopores. The existence of mesopore after HF etching provides more specific surface area and pore volume. However, NaOH etching produces more micropores, and the contribution of micropores to specific surface area and pore volume is higher than that of mesopores. Although HF and NaOH etching increase the specific surface area of SiOC ceramics, the etching effect of NaOH is superior to that of HF etching, and the carbon-enriched SiOC ceramics are obtained after NaOH etching.

SiOC as an alternative silicon-based material possesses great potential in lithium ion batteries due to its high reversible capacity, tunable chemical component and various synthetic route. However, large-scale production of SiOC powders grinded from SiOC bulks is restricted in commercial application because of the poor electrical conductivity. Herein, three dimensional (3D) lamellar SiOC@C/rGO composite is fabricated through hydrothermal reaction and electrostatic self-assembly process, in which SiOC powders encapsulated by amorphous carbon layers are homogeneously dispersed in graphene sheets. Cfree nanoclusters in SiOC, carbon layers on SiOC surface and graphene supporters in the composite establish the multidimensional interconnected conductive architecture and possess favorable interfacial adhesion. Therefore, SiOC@C/rGO exhibits high specific capacity (676 mAh g−1 at 200 mA g−1) and remarkable rate capability (306.4 mAh g−1 at 4000 mA g−1). The full cell assembled with this anode and LiFePO4 cathode also demonstrates stable voltage platform and good performance for 200 cycles. The excellent performance of SiOC@C/rGO profits from the synergistic effect of robust construction, multidimensional conductive architecture and chemical. Composition The proposed strategy can also be developed to prepare other materials with graphene layer to enhance their electrical conductivity for commercial application.

The number of spent lithium-ion batteries (LIBs) is constantly increasing as their popularity grows. It is important to develop a recycling method that not only can convert large amounts of waste anode graphite into high value-added products but also is simple and environmentally friendly. In this work, spent graphite from an anode was transformed into a cathode for dual-ion batteries (DIBs) through a two-step treatment. This method enables the crystal structure and morphology of spent graphite to recover from the adverse effects of long cycling and be restored to a regular layered structure with appropriate layer spacing for anion intercalation. In addition, pyrolysis of the solid electrolyte interphase into an amorphous carbon layer prevents the electrode from degrading and improves its cycling performance. The recycled negative graphite has a high reversible capacity of 87 mAh g−1 at 200 mA g−1, and its rate performance when used as a cathode in DIBs is comparable to that of commercial graphite. This simple recycling idea turns spent anode graphite into a cathode material with attractive potential and superior electrochemical performance, genuinely achieving sustainable energy use. It also provides a new method for recovering exhausted batteries.

Mechanochemical treatment (MTC) with SiC as an additive possessed a good performance on the degradation of hexachlorobenzene (HCB). However, this method consumed the additive of SiC and generated a toxic product of CCl4. This work attempted to add another additive, iron powder, to the MCT and explored the performance of the combined additive of SiC + Fe to solve this problem. Result indicated that CCl4 was not produced and SiC was not consumed when Fe was added in proper proportion. Compared with the single additive of SiC, the addition of Fe can further accelerate the degradation of HCB. The reaction pathway was proposed as: HCB can be mostly dechlorinated after a duration of MCT, and only trace-level low chlorobenzenes were generated under the effect of the combined additive. The left benzene skeletons can be broken to produce graphite and amorphous carbon. The shedding Cl radicals preferentially reacted with Fe to form FeCl3, and the reaction between Cl radicals and SiC and its toxic products can be avoided. Free electrons generated from the additive of SiC, fast reaction between Cl and Fe, and sparks in the MCT were considered the potential factors to accelerate the HCB degradation in MCT.

To deal with energy and environmental issues, it is necessary to exploit efficient and stable electrocatalysts for the generation of clean hydrogen. Herein, we describe the synthesis of bimetallic Fe/Ni alloy encapsulated by amorphous carbon shells via a facile annealing strategy for electrocatalytic oxygen evolution reaction (OER). The ferric nickel tartrate annealed at 800 °C (Ni3Fe1Ox@C-800) exhibits a low OER overpotential of 264 mV at 10 mA cm−2 and good stability in alkaline media. Compared with monometallic counterpart, bimetallic Ni3Fe-based nanocomposites show lower OER barrier (ca. 324 kJ mol−1) due to a cooperation mechanism between Ni and Fe sites in promoting electrocatalytic water oxidation. Compared with those annealed at other temperatures, the enhanced OER performance of Ni3Fe1Ox@C-800 can be ascribed to the large electrochemical surface area for exposing more active sites, smaller charge transfer, and better intrinsic activity of Ni3Fe-based sites.

Though amorphous carbon films are kinds of most distinguished lubricant materials, the friction coefficients of commercial amorphous carbon films are in the range of 0.05–0.40. To reduce the friction coefficients of those amorphous carbon films from the order of 0.01 to 0.001 range is still a big challenge. In order to solve the problem, in present work, a new strategy, called catalytic superlubricity, is proposed and carried out to achieve superlubricity by in-situ formation of graphene via introducing gold onto hydrogenated amorphous carbon (Au@a-C:H) film during friction. The results show that mulilayer graphene along with oriented polyolefin-like structures are formed due to the catalysis of Au nanoparticles, which is embedded in amorphous carbon matrix. Furthermore, the density functional theory calculations indicates that interlayer binding energy between graphene and the hydrogenated amorphous carbon (a-C:H) films’ surface is comparable to that between graphene layers, resulting in low interfacial interactions between sliding interfaces for low friction. Then, the low interfacial interactions lead to superlubricity with a friction coefficient of 0.003. This study opens up a new routing for facile and scale up fabrication of superlubricant a-C:H films in industrial applications.

Zirconia composites with few-layer graphene (FLG) were prepared by two powder processing routines -ultrasonic agitation or planetary ball milling- and spark plasma sintered at 1250 and 1300 °C. An in-depth study of the crystallinity of FLG, in terms of presence and nature of defects, was performed by Raman spectroscopy, revealing enhanced FLG crystallinity after sintering. This enhancement was more noticeable in the composites sintered at the highest temperature, with lower amount of structural defects and amorphous carbon. However, remaining amorphous carbon was detected in the composites prepared by planetary ball milling even after sintering at the highest temperature, resulting in lower electrical conductivities. Optimum results in terms of electrical conductivity were achieved for the composites prepared by ultrasonic agitation and sintered at 1300 °C, with electrical percolation limit below 2.5 vol% FLG and high electrical conductivity (678 S/m for 5 vol% FLG), as result of the enhanced FLG crystallinity after sintering.

Nanodiamonds (NDs) were prepared under ambient pressure by sublimation decomposition of silicon carbide in an intermediate frequency furnace for only 8 min. The synthesis proceeded in the temperature range of 2600-2800°C without any catalyst or highly active gas components (such as H2, alkane, and halogen). The conversion began at 2600°C and produced NDs with particle sizes in the range of 1-5 nm with a uniform particle shape and excellent dispersion. The linear reaction kinetics allowed for rapid transformation to any depth with reasonable control of the temperature. The linear rate constant (Kl) for the reaction at 2800°C was 37.5 mm/h, which is 31.2 times that of the reaction at 2600°C. The SiC sublimation decomposition produced carbon atoms that filled the SiC lattice vacancies or were combined with the suspended carbon chain bonds to form sp3 carbon, while the diffusion of amorphous carbon atoms promoted nucleation and growth of diamond. High-resolution transmission electron microscopy analysis indicated that the NDs were separated from the SiC matrix by break-off due to propagation of the reaction front. This SiC sublimation decomposition method is considered simple, fast, environmentally friendly and promising for industrial-scale production.

Thermally insulating and fire-resistant carbon composite foams are prepared by consolidating natural cotton fibre dispersed in aqueous sucrose solution by filter-pressing followed by drying and carbonization. The compressive strength (5 kPa to 1.4 MPa) and thermal conductivity (0.069 to 0.185 W m − 1 .K − 1) depend on the foam density (0.06 to 0.31 g cm−3) which is modulated by varying the sucrose solutions concentration (100 to 700 g L − 1). Partially flexible to the rigid transition of the carbon composite foams occurs at sucrose concentration above 200 g L − 1. The tubular carbon fibre formed from cotton is welded at their contact points by the amorphous carbon produced from sucrose leading to partial flexibility at low sucrose concentration and advancement of fibre- to- fibre bonding area at higher sucrose concentration results in rigid foam. The porosity in the inter-fibre space and lumen of the carbonized cotton fibre contributes to the low thermal conductivity. The carbon composite foams prepared at a sucrose solution concentration of 500 g L − 1 and above are amenable to machining using conventional machines and tools. The rigid carbon foams show EMI shielding effectiveness and specific shielding effectiveness in the ranges of 21.5 to 38.9 dB and 108–138 dB cm3 g − 1, respectively.

The objective of this investigation was to determine the efficiency of carbonaceous material, consisting of MWCNTs and amorphous carbon obtained by waste polyethylene pyrolysis, as an adsorbent for reactive textile dyes. In this work, the preliminary results of adsorption process of Bezaktiv Blau V-3R reactive dye from a solution with an initial 30 mg/l concentration using low dosage of adsorbent are presented. The results show that this material has promising potential as a sorbent, and its adsorption capacity (140 mg/g) for a reactive (anionic) dye is similar to some commercial MWCNT and functionalized MWCNT-based adsorbents.

The present work emphasizes synthesis and evaluation of rice husk (RH) derived nano structured silica material as support for Ni in the catalytic methane cracking (CMC) process. CO chemisorption results showed the 15 wt%Ni/RH-SiO2 catalyst exhibited a higher ratio of surface decorated Ni sites compared to other Ni loadings. TEM analysis of deactivated catalysts indicated the formation of carbon nano materials (mostly CNT/CNF) along with pure H2. Raman spectroscopic analysis of the deactivated catalysts exhibited a low proportion of graphitic carbon with a shift at 1320 cm−1 than the amorphous carbon band at 1580 cm−1. The superior performance of Ni supported on SiO2 was rationalized by H2-TPR, 29Si MAS NMR, XRD and BET-surface area analyses.

In this paper, C and Ti were used as the deposition atoms in the molecular dynamics model. The effects of Ti doping percentages (2, 8, 14, and 20 atom %) on the structure and internal stress of a-C films were investigated. The results showed that with the increase in the Ti percentage, the density of the intrinsic zone is gradually increased, while the growth rate is slowly decreased. The internal stress is gradually changed from compressive stress to tensile stress. Among them, when the Ti percentage is 14 atom %, the internal stress is closer to 0. The C percentage with sp3 hybridization is decreased, while those with sp2 and sp hybridizations are increased. The positions of the first and second peaks in the RDF were shifted to the left. Moreover, the distribution of bond lengths and bond angles in the intrinsic zone tend to change from diamond to graphite, which proves that Ti doping leads to the graphitization of a-C films. In addition, Ti doping affects the internal stress of a-C films by changing the C percentage with sp3 hybridization in them.

Activated carbon (AC) from sugarcane bagasse was prepared using a simple two-step method of carbonization and chemical activation with four different activating agents (HNO3, H2SO4, NaOH, and KOH). Amorphous carbon structure as identified by X-ray diffraction was observed in all samples. Scanning electron microscopy revealed that the AC had more porosity than the non-activated carbon (non-AC). Specific capacitance of the non-AC electrode was 32.58 F g−1 at the current density of 0.5 A g−1, whereas the AC supercapacitor provided superior specific capacitances of 50.25, 69.59, 109.99, and 138.61 F g−1 for the HNO3 (AC-HNO3), H2SO4 (AC-H2SO4), NaOH (AC-NaOH), and KOH (AC-KOH) activated carbon electrodes, respectively. The AC-KOH electrode delivered the highest specific capacitance (about 4 times of the non-AC electrode) because of its good surface wettability, the largest specific surface area (1058.53 m2 g−1), and the highest total specific pore volume (0.474 cm3 g−1). The AC-KOH electrode also had a great capacitance retention of almost 100% after 1000 GCD cycles. These results demonstrate that our AC developed from sugarcane bagasse has a strong potential to be used as high stability supercapacitor electrode material.

To reveal the effect of reaction temperature on the reduction of diesel particulate matter (PM) by non-thermal plasma (NTP) using oxygen as a gas source. The changes in the microcrystalline structure and the elemental state of PM before and after NTP oxidation at different temperatures were explored by Raman and X-ray photoelectron spectroscopy. After NTP oxidation, the disorder in the PM microcrystal structure and the amorphous carbon structure was reduced. The full width at half maximum (FWHM) of the D1 and D3 peaks decreased, and the FWHM of the G peak increased slightly. During the oxidation of PM, the carbon microcrystals grew and became restructured, and the graphitization of PM increased. After NTP oxidation, the content of O in PM increased as the reaction temperature increased, resulting in a gradual change in the binding form of O with C from C-O to C=O. The ability of temperature rise to promote the oxidation activity of NTP was gradually weakened for the thermal decomposition of NTP active substances. The microcrystalline structure and the occurrence state of C and O of PM changed with reaction temperature, indicating that the oxidizability of NTP on PM differed at different reaction temperatures.

The diamond-like carbon- (DLC-) coating technique is used in the sliding parts of automotive engines, among other applications, to reduce friction and wear. In this work, DLC has been coated on the Aluminium 5051 sample to assess the mechanical and tribological properties. A sputtering deposition mechanism is used, and the DLC is coated using a graphite target. The developed DLC coatings are tested for adhesion strength, hardness, chemical composition using XRD, and wear behaviour. The developed DLC thin films have considerably increased the wear behaviour of the Aluminium 5051 sample and have fulfilled the objective of this study. The XRD data indicated the presence of amorphous carbon in the coating with a threefold increase to the hardness of the naked aluminium. This study provides insight into improving the aluminium wear resistance by developing a considerably hard coating.

Chemical vapor deposition (CVD)-grown graphene films on Cu foils, exhibiting fine scalability and high quality, are still suffering from the adverse impact of surface contamination, i.e., amorphous carbon. Despite the recent successful preparation of superclean graphene through Cu-vapor-assisted reactions, the formation mechanism of amorphous carbon remains unclear, especially with regard to the functions of substrates. Herein, we have found that the crystallographic orientations of underlying metal substrates would determine the cleanness of graphene in such a way that slower diffusion of active carbon species on as-formed graphene-Cu(100) surface is the key factor that suppresses the formation of contamination. The facile synthesis of clean graphene is achieved on the meter-sized Cu(100) that is transformed from the polycrystalline Cu foils. Furthermore, a clean surface of graphene on Cu(100) ensures the reduction of transfer-related polymer residues, and enhanced optical and electrical performance, which allows for versatile applications of graphene in biosensors, functioning as flexible transparent electrodes. This work would offer a promising material platform for the fundamental investigation and create new opportunities for the advanced applications of high-quality graphene films.

The wettability of graphene is critical for numerous applications but is very sensitive to its surface cleanness. Herein, by clarifying the impact of intrinsic contamination, i.e., amorphous carbon, which is formed on the graphene surface during the high-temperature chemical vapor deposition (CVD) process, the hydrophilic nature of clean graphene grown on single-crystal Cu(111) substrate was confirmed by both experimental and theoretical studies, with an average water contact angle of ∼23°. Furthermore, the wettability of as-transferred graphene was proven to be highly dependent on its intrinsic cleanness, because of which the hydrophilic, clean graphene exhibited improved performance when utilized for cell culture and cryoelectron microscopy imaging. This work not only validates the intrinsic hydrophilic nature of graphene but also provides a new insight in developing advanced bioapplications using CVD-grown clean graphene films.

Potassium ion batteries (KIBs) have attracted great attention recently as a promising large-scale energy storage system by virtue of the bountiful K resource and low standard hydrogen potential of K+/K. However, their development is hindered by the limited capacity and inferior cycling stability resulting from the large size of K+. Here, a unique vanadium sulfide@carbon nanorod is designed and synthesized for high-performance KIBs. Thanks to the hybrid structure, abundant active sites, fast ion diffusion, and capacitive-like electrochemical behavior of the electrode, the anode exhibits a large specific capacity (468 mA h g-1 after 100 cycles at 0.1 A g-1), predominant rate performance (205 mA h g-1 at 5 A g-1), and impressive cycling stability (171 mA h g-1 for 4000 cycles at 3 A g-1). Furthermore, the constructed KIB full cell demonstrates 229 mA h g-1 at 0.5 A g-1 and 86% capacity retention over 300 cycles.

Reactive molecular dynamics (MD) simulations are performed to study the initial stage of the oxidation of carbon fiber and amorphous carbon char with atomic oxygen at temperatures ranging from 1000 K to 4500 K. The carbon fiber and amorphous char models are generated by kinetic Monte-Carlo and liquid quench methods, respectively. The species formed in the simulation are characterized and carbon monoxide is found to be the primary product in both systems. The oxidation results are analyzed in terms of the lifetime of molecules and the reaction rates of various species. Oxygen is found to be adsorbed on the surface of both carbon fiber and amorphous carbon char. Since the amorphous carbon has a significantly larger surface area, the number of oxygen atoms adsorbed on the amorphous carbon surface is significantly higher than on the carbon fiber surface. Six reaction models are proposed to fit the simulation results from which reaction rates at various temperatures are obtained. Reaction rates of the key reactions: carbon oxidation and oxygen adsorption follow the Arrhenius law and the activation energy is extracted for these reactions. These reaction rates are used to predict the long-time evolution of these systems.

Aiming at enhancing the coke resistance of Ni-based catalysts, the Nd-doped Ni@A2O3 core-shell catalysts were prepared and their catalytic performance was evaluated in the steam reforming of acetic acid (SRAA). The catalysts were characterized by BET, XRD, XRF, HRTEM, H2-TPR, NH3-TPD, and DTG. The catalytic performance was greatly enhanced by the incorporation of Nd, with decreased yields of CO, CH4, and acetone, increased yield of CO2, and remarkable carbon resistance. The decoking behavior of the spent catalyst was elucidated by H2O18-TSD. A low reaction temperature facilitates the formation of amorphous carbon, leading to catalyst deactivation. The decoking ability of the catalyst is greatly improved by the Nd incorporation but is also catalyzed by the exposed Ni surface. The Ni0.01Nd@Al catalyst greatly balanced the exposed Ni surface and the mobile lattice oxygen, showing the highest catalytic activity, lowest coke deposition, and superb decoking ability.

A low crystalline 1T-MoS2@S-doped carbon (MoS2@SC) composite was successfully synthesized via a facile hydrothermal process. The composite is comprised by few-layer 1T-MoS2 nanosheets covered by an amorphous carbon layer with an expanded interlayer d-spacing of 1.01 nm. This structure is conducive to the fast transport of lithium-ions and volume accommodation during the charge–discharge process when the composite is applied as an anode material for LIBs. Additionally, the high conductivity and layered structure of 1T-MoS2 also facilitate fast of ion/electron transport, contributing to the improvement of the electrochemical properties. Therefore, this material demonstrated a high rate performance and excellent cycling stability, with the capacities of 847 and 622 mA h g−1 achieved at the current densities of 0.2 A g−1 and 2 A g−1, respectively. Even at a larger current density of 2 A g−1, MoS2@SC delivered a high reversible capacity of 659 mA h g−1 with an average capacity loss of 0.006% per cycle after 500 cycles.

In this study, the amorphous carbon thin films were deposited by ion beam sputtering deposition method on the glass and Ni–Cu alloy substrates. The structural evolution of amorphous carbon and its correlation with the kinetic energy of carbon atoms during the growth of thin film was investigated. The effect of substrate material, deposition temperature, and ion beam energy on the structural changes were examined. Raman spectroscopy indicated a structural transition from amorphous carbon to diamond-like amorphous carbon (DLC) due to an increase in deposition temperature up to 100°C and ion beam energy from 2 keV to 5 keV. The size of graphite crystallites with sp2 bonds (La) were smaller than 1 nm in the amorphous carbon layers deposited on Ni-Cu alloy. The results of residual stress calculation using X-ray diffractometer (XRD) analysis revealed a decreasing trend in the tensile residual stress values of the amorphous carbon thin films with increasing the ion beam energy.

One of the long-standing challenges in experimental superconductivity are the sustained efforts to achieve stable and cheap superconducting materials at room temperatures. There are still no guiding paths or theories, to fulfill this aspiration. It appears that most of the high-Tc superconducting materials reported in the last 3–4 decades were accidently discovered. Recently, high-temperature superconductors in various hydrogen-rich compositions have been reported. However, all these substances superconduct under extremely high pressures only, not achievable in most laboratories. In this review article, we summarize two unsuccessful methods used by us to achieve high-Tc superconductors under ambient pressure. We summarize our observations made on the basis of the conventional superconducting-magnetic phase diagrams and on the YFe2X2 (X = Si, Ge) systems in which Fe is not magnetic. On the other hand, superconducting phases up to 65 K were accidently discovered in commercial amorphous carbon (a-C) which contains traces of sulfur. The third part describes attempts to produce superconductivity in synthesized a-C powders and thin-film doped with sulfur (a-CS at ambient pressure. The a-CS materials have the same ingredients as the recent CH4-H2S-H2 gases, which are superconducting at Tc = 289 K under high pressure of 267 GPa.

A hydrogenated amorphous carbon (a-C:H) film shows an ultralow friction coefficient (COF, lower than 0.01); however, its wear life is short in vacuum, and the mechanisms are still not well-understood. This study demonstrates the vacuum tribological behaviors of the a-C:H film can be regulated by interfacial activity. The strong interfacial activity induced continuous transfer of carbon from the film to counterface, causing the formation of a porous transfer film and severe wear of the a-C:H film. Interestingly, weak interfacial activity is beneficial to form spherical-like carbon at the sliding interface, which shields the interaction of dangling bonds and contributes to lower COF and wear of film. Notably, the catalytic nature of Au induced perfect graphene nanoscrolls around Au nanoparticles at the sliding interface, achieving ultralong vacuum wear life. This Letter unifies the understanding of vacuum tribological properties of a-C:H film and provides new insight for prolonging the life of carbon films in vacuum.

With the goal to delevop the fabrication of a new type of Pt-nanoparticle carbon-support electrocatalyst, we investigate the carbon embedding of Pt cluster superlattices grown on the moiré of a monolayer of hexagonal boron nitride (h-BN) on Ir(111). Our combined scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) study establishes conformal C embedding of the Pt clusters on h-BN/Ir(111) without deterioration of superlattice order, preferential and strong binding of the embedding carbon to the Pt clusters, and upon annealing the formation of a homogeneous amorphous carbon (a-C) matrix. There are indications that while the a-C matrix and the Pt clusters bind strongly to each other, upon annealing both weaken their binding to h-BN.

In this experimental study, a commercially available polyurethane (PU) sponge coated with amorphous carbon spheres (ACSs) is investigated for oil/water separation. The ACSs synthesized using chemical vapor deposition are embedded in the PU sponge by a simple dip-coating method. The superhydrophobic ACS-PU sponge exhibits a water contact angle (WCA) of 156.2 ± 1° and a sliding angle

Constructing magnetic/dielectric composites with core-shell structure is an effective strategy for the development of high-efficiency microwave absorbers owing to the synergistic effect of multiple attenuation mechanisms. In this work, FeCo2O4 nanoparticles of 8 nm prepared by the nitrate decomposition method were used as the precursor, and the core-shell structured Co7Fe3@C nanocapsules with an average particle size of only 30 nm were fabricated through subsequent carbonization-reduction process. The Co7Fe3@C nanocapsules exhibit high-efficient microwave absorption performance. At an ultra-thin thickness of 1.6 mm, the minimum reflection loss (RL) value reaches up to −117.4 dB at 11.9 GHz. Notably, at the same thickness, the effective absorption bandwidth (RL ≤ −10 dB) is as wide as 9.2 GHz (8.8–18 GHz), covering almost the whole X and Ku bands. Moreover, the microwave absorption mechanism is revealed in detail through in-depth analysis of electromagnetic parameters. The outstanding microwave absorption capability is ascribed to the synergetic effect of strong magnetic loss of Co7Fe3 alloy cores and strong dielectric loss of amorphous carbon shells, as well as the superior impedance matching. It is believed that the core-shell structured Co7Fe3@C nanocapsules should be promising as high-efficiency microwave absorbers with thin thickness, strong absorption strength and broad absorption bandwidth.

Background Up-cycling of waste papers to value-added carbon products has significant environmental and economic benefits in real life. This work aims to recycle the waste papers to construct amorphous carbon modified graphitic carbon nitride composite photocatalysts for efficient photocatalytic hydrogen generation from water under visible light. Methods Amorphous carbon (labeled as a-C) was yielded from the office waste papers by simple sulphuric-acid treatment and then combined with graphitic carbon nitride (g-CN) to form the g-CN/a-C composite photocatalysts by the thermolysis of a-C and melamine mixture. Significant Findings The addition of a-C enlarges the surface area of g-CN from 11.52 m2 g−1 of pristine g-CN to 28.12 m2 g−1 of g-CN/a-C-100. In addition, the a-C incorporation can significantly separate the electrons from the photoexcited g-CN owing to the excellent conductivity of a-C. As a result, an increased photocatalytic H2 generation was realized under visible light exposure. The g-CN/a-C-100 sample with optimized a-C contents offers the highest photocatalytic H2 generation rate of up to 17.1 μmol h−1, which is ∼12 times higher than that of pristine g-CN under the same condition. The present study manifests the great potential of the recycling of office waste papers for increased photocatalytic H2 generation.

We report the structural transformations of carbon via the melt spinning and subsequent annealing of nickel-carbon alloys. We attained metastable solid solubility of carbon in nickel ribbon by achieving a rapid solidification rate of up to 1.6 × 106 K/s. Excess carbon atoms were found to be dissolved in the nickel lattice causing up to 1.4% strain for an alloy spun at 70 m/s tangential wheel speeds. High temperature heat treatments led to precipitation of carbon from the nickel lattice on the ribbon free surfaces but also led to growth of spherical precipitates within the nickel matrix, an effect consistent with bulk diffusion-driven Ostwald ripening. Carbon was excavated from the ribbons via chemical dissolution of the metal and characterized by electron microscopy and Raman spectroscopy. We found that the microstructure of carbon precipitated from the rapidly quenched ribbon could be tuned by varying the carbon content from 4 to 12 at. % in the precursor and annealing the ribbon at temperatures that ranged from 400 to 1200 °C. Via the step-wise variation of these two parameters, we sequentially transformed amorphous carbon nanospheres with a high BET surface area of 203 m2/g into thick, highly crystalline flakes of graphite that conformed to the shape of the as-spun ribbon.

Minimizing the wear of the surfaces exposed to mechanical shear stresses is a critical challenge for maximizing the lifespan of rotary mechanical parts. In this study, we have discovered the anti-wear capability of a series of metal nitride-copper nanocomposite coatings tested in a liquid hydrocarbon environment. The results indicate substantial reduction of the wear in comparison to the uncoated steel substrate. Analysis of the wear tracks indicates the formation of carbon-based protective films directly at the sliding interface during the tribological tests. Raman spectroscopy mapping of the wear track suggests the amorphous carbon (a-C) nature of the formed tribofilm. Further analysis of the tribocatalytic activity of the best coating candidate, MoN-Cu, as a function of load (0.25–1 N) and temperature (25 °C and 50 °C) was performed in three alkane solutions, decane, dodecane, and hexadecane. Results indicated that elevated temperature and high contact pressure lead to different tribological characteristics of the coating tested in different environments. The elemental energy dispersive x-ray spectroscopy analysis and Raman analysis revealed formation of the amorphous carbon film that facilitates easy shearing at the contact interface thus enabling more stable friction behavior and lower wear of the tribocatalytic coating. These findings provide new insights into the tribocatalysis mechanism that enables the formation of zero-wear coatings.

We predict the three-dimensional structure of amorphous carbon generated by heating diamond superlattice at 6000 K with rapid quenching from the liquid phase for densities ranging from 2.0 to 3.5 g/cm³, in comparison with 2.26 and 3.54 g/cm³ for bulk graphite and bulk diamond, respectively. These predictions are based on reactive dynamics (RD) simulations using the ReaxFF reactive force field. Here, we simulate the graphitization of amorphous carbon at high temperature to calculate physical properties relevant to conductive carbon supports useful for electrocatalysts. The low-density graphitic materials mostly oriented in the (002) plane with a main X-ray diffraction (XRD) peak between 26 and 28°, as observed experimentally. For low density carbon (2.0–2.5 g/cm³), we find >90% sp² character with ∼2-1% sp and

Proton exchange membrane fuel cells (PEMFCs) are operated in a range of different environments including near-dry operating conditions. When a PEMFC operates under low relative humidity (RH) conditions, performance degradation rapidly occurs because of the decreased ionic conductivity of dehydrated membrane electrode assemblies (MEAs). As such, securing additional water inside the MEA is important for achieving a high-performance PEMFC under low RH operating conditions. Herein, amorphous carbon-encapsulated carbon nano-onions (AC-CNOs) were prepared by laser pyrolysis method. The hydrophilicity of AC-CNOs varied on the basis of particle size, which affected the amount of oxygen functional groups attached to the amorphous carbon. To confirm the water retention effect of the AC-CNOs, three different catalysts were incorporated into the MEA of the anode electrode, and a Pt@AC–CNO–3 with an average AC-CNO size of ∼164 nm exhibited a significantly improved performance under low RH condition. Moreover, to achieve a synergetic effect from both the anode and cathode, an additional AC-CNO layer was introduced on the cathode catalyst layer. The dual-side MEA with the hydrophilic catalyst layer at the anode and an additional carbon covering layer at the cathode showed significantly increased performance relative to the reference MEA, i.e., >80.2% under RH44%@90 °C conditions.

In this paper, SnO2 nanoparticles were designed and synthesized by the hydrothermal method. It was confined to a jute fiber cellulose carbon (JFCC) framework, which was equivalent to a biomass carbon buffer layer wrapped around SnO2 nanoparticles. The combination of SnO2 nanoparticles and the amorphous carbon buffer layer alleviated the volume expansion effect of SnO2 to a certain extent, shortened the lithium-ion diffusion path, and improved the conductivity. At 0.2C, the discharge specific capacity of the composite (SnO2@JFCC) was finally stabilized at 1298.5 mAh g−1 after 100 cycles. The discharge specific capacity was stabilized at 1090.3 mAh g−1 for 1000 cycles at 2C, which further showed the good synergy between SnO2 nanoparticles and JFCC and exhibited excellent lithium storage performance.

The creation and properties of porous carbons are of extreme importance for optimizing the performance of battery and supercapacitor electrodes, as well as vehicular hydrogen storage. Atomistic simulation methods with reactive potentials have shown promise to create realistic porous carbon structures. However, such models have been unable to reproduce low-density microporous carbon structures due to clustering of atoms in high density regions, resulting in a small number of mesopores. Here we present a new method using virtual voids, generating excluded volume by a soft repulsive potential which is progressively decoupled from the carbon atoms. This allows us to prevent densification and to create disordered carbon models with porosities up to 90%. We vary the size and density of the virtual voids and show that the mean of the pore size distribution and the accessible surface area can be controlled. By choosing the desired porosity and virtual void size, we create amorphous carbon models with mean pore sizes ranging from 10 to 32 A, which agree favorably with experimental pore sizes for low-density microporous carbons.

Nanostructured coatings based on amorphous carbon and carbon-doped with gold, silver, and nitrogen were obtained by the pulsed vacuum-arc method. Carbon coatings have been annealed in a vacuum as well as treated with argon ions. The alloying of carbon coatings with elements that do not form chemical bonds with the carbon matrix (Ag, Au) leads to the formation of gold or silver nanocrystallites with sizes of 2 ‑ 20 nm in the matrix of amorphous carbon, whose density depends on the concentration of the doping element. Annealing of silver-doped carbon coatings leads to the formation of islands on the surface with the size of the order of micrometers. This is due to the silver diffusion and coalescence of small islands into larger ones. The HRTEM method discovered the effect of twinning in carbon nanocrystallites after vacuum annealing as well as silver and gold in the initial state (the formation of single-crystal regions with an altered orientation of the crystal structure) in the amorphous carbon matrix. Analysis of Raman spectra of pure carbon coating and silver-doped showed that the addition of silver leads to a decrease in sp3-phase in the carbon matrix. This effect is particularly evident in the nature of changes in the spectra after vacuum annealing at 600 ºC. The addition of nitrogen in the carbon coating leads to an increase in the sp2 ‑ phase fraction, and additional annealing leads to a significant increase in the D - peak intensity and formation of clusters of the order of 5 ‑ 15 nm, which are not localized but fill the entire space. Analysis of the coating a-C: Au irradiation with argon ions shows that the number of nanopitches decreased after ion irradiation, simultaneously decreased surface roughness degree, besides, decreased electrical conductivity of the coating as a result of decreased gold content. It was found that the conditions of nanostructured coatings and their subsequent processing allow controlling the properties of nanocoatings (structure, size of nanoparticles, surface topography, and electrical conductivity).