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Although widely studied experimentally in the 1990s, the structure and properties of low-dimensional or high-pressure phases of fullerenes have recently been re-examined. Remarkably, recent experiments have shown that transparent, nearly pure amorphous sp3-bonded carbon phases can be obtained by heating a C60 molecular crystal at a high pressure. With the additional aim of testing the ability of three classical carbon potentials reactive empirical bond order, environment-dependent interatomic potential, and reactive force-field to reproduce these results, we investigate the details of the structural transformations undergone by fullerene crystals over a wide range of pressures and temperatures. All the potentials tested show that the initial polymerization of fullerenes is accompanied by negative thermal expansion, albeit in slightly different ranges. However, more significant differences in structural and mechanical properties are observed in the amorphous phases, in particular the sp3 carbon fraction and the existence of layered amorphous carbon. Overall, these results indicate to which extent classical reactive potentials can be used to explore phase transitions over a wide range of pressures and temperatures. [ABSTRACT FROM AUTHOR]

Amorphous carbon nitride (a-CNx) films, prepared by reactive radio frequency magnetron sputtering, exhibit unique characteristics under visible light irradiation, referred to as photoinduced deformation. This phenomenon represents an energy conversion system wherein photon energy transforms into kinetic energy. The chemical bonding structure of a-CNx films was analyzed using near-edge x-ray absorption fine structure (NEXAFS) at the NewSUBARU synchrotron facility of the University of Hyogo, Japan. This analysis aimed to elucidate the mechanisms behind the photoinduced deformation observed in a-CNx films. Three variants of a-CNx films, displaying varying degrees of photoinduced deformation, were deposited using a graphite target and nitrogen gas under different deposition temperatures. The NEXAFS spectra of the a-CNx films with substantial photoinduced deformation showed changes under light irradiation from a Xe lamp (directed through an optical window within the NEXAFS chamber). Specifically, the peaks corresponding to the 1s to π* transition related to C—C and 1s to σ* transition related to C—N bonds exhibited high sensitivity to visible light irradiation. Simultaneously, the N K-edge spectra associated with the 1s to π* transition, attributed to the N—C bond, exhibited a slight intensity decrease. Conversely, the C K-edge spectrum in the a-CNx films displaying minimal photoinduced deformation remained unchanged under visible light irradiation. The N K-edge spectra maintained a consistent shape under both visible light and dark conditions. [ABSTRACT FROM AUTHOR]

Ge-Sb-Te (GST) alloys are leading phase-change materials for data storage due to the fast phase transition between amorphous and crystalline states. Ongoing research aims at improving the stability of the amorphous phase to improve retention. This can be accomplished by the introduction of carbon as a dopant to Ge2Sb2Te5, which is known to alter the short- and mid-range structure of the amorphous phase and form covalently bonded C clusters, both of which hinder crystallization. The relative importance of these processes as a function of C concentration is not known. We used molecular dynamics simulation based on density functional theory to study how carbon doping affects the atomic structure of GST-C. Carbon doping results in an increase in tetrahedral coordination, especially of Ge atoms, and this is known to stabilize the amorphous phase. We observe an unexpected, non-monotonous trend in the number of tetrahedral bonded Ge with the amount of carbon doping. Our simulations show an increase in the number of tetrahedral bonded Ge up to 5 at.% C, after which the number saturates and begins to decrease above 14 at.% C. The carbon atoms aggregate into clusters, mostly in the form of chains and graphene flakes, leaving less carbon to disrupt the GST matrix at higher carbon concentrations. Different degrees of carbon clustering can explain divergent experimental results for recrystallization temperature for carbon doped GST. [ABSTRACT FROM AUTHOR]

This paper explores the unintentional contamination of Surface-Enhanced Raman Scattering (SERS) substrates by ambient hydrocarbon contaminants and their contribution to SERS spectra. Previous studies have identified amorphous carbon as a potential complicating factor in data analysis in SERS experiments, although its origin has been elusive. Our work showed that ambient hydrocarbon contamination and its decomposition products can be detected by SERS on a gold substrate. We propose that ambient air itself is a source of amorphous carbon contamination on SERS substrates. This understanding is crucial for the correct interpretation of SERS data and highlights the need for careful consideration of potential environmental contaminants in SERS analysis. [ABSTRACT FROM AUTHOR]

C-incorporated amorphous silica (a-SiOC) is expected to be a significant dielectric film for miniaturized semiconductor devices. However, information on the relationship among its composition, atomic structures, and material properties remains insufficient. This study investigated the dependence of the elastic modulus on the C content in a-SiOC, employing a universal neural network interatomic potential to realize a high-accuracy and high-speed simulation of multicomponent systems. The relationship between elastic modulus and atomic network structures was explored by fabricating 480 amorphous structures through the melt-quenching method without predetermined structure assumptions. The bulk modulus increased from 45 to 60 GPa by incorporating 10% C atoms under O-poor conditions and 20% C atoms under O-rich conditions, respectively. This result is attributed to the formation of denser crosslinking atomic network structures. In particular, the C atoms bonded with the Si atoms with higher coordination under O-poor conditions, whereas they tend to bond with O atoms under O-rich conditions, breaking the SiO2 network. Large C clusters precipitated as the C fraction was increased under O-rich conditions. Gas molecules, such as CO and CO2, were also generated. These results are consistent with reported ab initio calculation results of the formation energies of C defects and gas molecules in SiO2. The findings suggest that realizing O-poor conditions during deposition is crucial for fabricating stronger dielectric films. Therefore, this work contributes to understanding the fabrication of stronger dielectric films and elucidating the underlying mechanism of C cluster formation. [ABSTRACT FROM AUTHOR]

The tetrahedral amorphous carbon (ta-C) coatings are deposited on piston rings to improve the tribological property of the piston ring-cylinder liner system of the internal combustion engines. The deposition parameters are optimized by molecular dynamics simulation to reduce the cost of coatings' fabrication. The ta-C coatings with higher sp3 fraction, lower friction coefficient, and superior anti-wear properties are achieved by optimizing the incident energy and substrate temperature of carbon atoms. The second nearest-neighbor modified embedded-atom method potential and Tersoff potential are used to describe the interatomic interactions. The effects of the incident energy of the carbon atoms and substrate temperature on the deposition properties of the ta-C coatings are discussed. The numerical results show that the ta-C coatings with high sp3 fraction, high density, and good interface mixing are obtained, and the deposition properties of the ta-C coatings are improved. [ABSTRACT FROM AUTHOR]

A systematic review and meta-analysis of sputter yield data for xenon ions normally incident on graphite at energies below 2000 eV was undertaken to identify systematic errors, determine the best model parameter values to represent yield as a function of energy, quantify uncertainty, and determine if the data support differences in yields for different types of graphite. A critical examination of the 11 published data sets for high density graphite, pyrolytic graphite, and amorphous carbon showed that, in general, they were carefully controlled to minimize errors. The most significant quantifiable systematic errors were those caused by the neglect of doubly charged ions, chemical erosion, and the impact of secondary electron emission on ion flux measurements. The effects of gas uptake and outgassing on mass loss measurements and unrepresentative surface textures may have biased other experiments, but these effects could not be quantified. The semi-empirical Eckstein model for yield as a function of energy was fit to data for the three graphite types using a hierarchical Bayesian statistical model, producing recommended fit parameters and probability distributions representing uncertainty in yields. The results showed that differences in yield for high density graphite and pyrolytic graphite were not statistically significant. Apparent differences in yield for amorphous carbon disappeared when the single data set available for energies below 150 eV was corrected for reasonable values of double ion content. Recommended procedures to avoid systematic errors and additional experiments and modeling to fill in gaps in our understanding are included. [ABSTRACT FROM AUTHOR]

Carbon-doped Ge2Sb2Te5 (CGST) is a potential candidate in phase change random access memory (PCRAM) with superb thermal stability and ultrahigh cycle endurance. Direct observation of the microstructure evolution of CGST is desirable to uncover the phase transformation mechanism on the relationship of nucleation/crystalline behaviors of the crystalline phase at elevated temperatures and the pristine amorphous phase at room temperature. Here, we investigate the structural evolution of CGST using combined in situ techniques. Our in situ x-ray diffraction and ellipsometry results demonstrate that CGST exhibits a much higher phase transition temperature than undoped one. Temperature-dependent in situ transmission electron microscopy observations further reveal that carbon doping plays a critical role in tailoring the properties of GST by tuning the stochasticity of nucleation/crystallization, stabilizing amorphous and crystalline GST via isolating and refining the grain size at room temperature and elevated temperature. Our work provides detailed information for understanding the microscopic origin of crystallization kinetics of carbon-doped phase change materials toward high-performance PCRAM. [ABSTRACT FROM AUTHOR]

Direct bandgap group IV materials could provide intimate integration of lasers, amplifiers, and compact modulators within complementary metal–oxide–semiconductor for smaller, active silicon photonics. Dilute germanium carbides (GeC) with ∼1 at. % C offer a direct bandgap and strong optical emission, but energetic carbon sources such as plasmas and e-beam evaporation produce defective materials. In this work, we used CBr4 as a low-damage source of carbon in molecular beam epitaxy of tin-free GeC, with smooth surfaces and narrow x-ray diffraction peaks. Raman spectroscopy showed substitutional incorporation of C and no detectable sp2 bonding from amorphous or graphitic carbon, even without surfactants. Photoluminescence shows strong emission compared with Ge. [ABSTRACT FROM AUTHOR]

Direct bandgap group IV materials could provide intimate integration of lasers, amplifiers, and compact modulators within complementary metal–oxide–semiconductor for smaller, active silicon photonics. Dilute germanium carbides (GeC) with ∼1 at. % C offer a direct bandgap and strong optical emission, but energetic carbon sources such as plasmas and e-beam evaporation produce defective materials. In this work, we used CBr4 as a low-damage source of carbon in molecular beam epitaxy of tin-free GeC, with smooth surfaces and narrow x-ray diffraction peaks. Raman spectroscopy showed substitutional incorporation of C and no detectable sp2 bonding from amorphous or graphitic carbon, even without surfactants. Photoluminescence shows strong emission compared with Ge. [ABSTRACT FROM AUTHOR]

Hollow transition metal carbides (TMCs) have broad potential applications due to their high melting point, low density, high specific surface area, and good electrical conductivity. However, the conventional preparation of TMCs often involves complex processes and requires high temperature, which limits their practical application. Herein, hollow TMC powders including NbC, VC, ZrC, and TiC were successfully prepared by one-pot molten salt synthesis (MSS) at relatively low temperatures. The formation mechanism and the influence of carbon crystallinity on the synthesis process were investigated. It was found that amorphous carbon precursors act as sacrificial templates in MSS, which can induce the Kirkendall effect to form the hollow structure. When using graphitized carbon microspheres as carbon precursors, the reaction between transition metals and carbon is uneven and relatively sluggish, which prevents the occurrence of the Kirkendall effect, thus hindering the formation of hollow structure. This work provides a facile method to prepare hollow TMCs with the advantages of low synthesis temperature and adjustable morphology. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries are recognized as an encouraging alternative for future power storage technologies. However, their practical application is hindered by several significant challenges, including slow redox kinetics, the shuttle effect, and the formation of lithium dendrites. Here a binder-free, self-supporting multifunctional interlayer composed of lithium lanthanum titanate (LLTO) with amorphous carbon nanofiber matrices for Li–S batteries has been constructed. This multifunctional interlayer has been designed to facilitate the redox kinetics of lithium polysulfides (LiPSs), promote the nucleation of lithium sulfide (Li2S), and hinder the formation of lithium dendrites. The electrocatalytic properties of the interlayer were subjected to systematic evaluation through electrochemical testing, and the lithium deposition was assessed by examining the surface evolution of lithium metal in symmetric cells. The LLTO carbon matrix interlayer sustained a high specific capacity of 703.3 mA h g−1 after 200 cycles at 0.1C, with a sulfur loading of 5.5 mg cm−2. Furthermore, it demonstrated a high capacity of 905.9 mA h g−1 with a decay rate of 0.069% per cycle over 1000 cycles at a current density of 5C with a sulfur loading of 1 mg cm−2. This investigation highlights the potential of LLTO carbon composite materials as multifunctional interlayers, which could facilitate the optimization of advanced Li–S batteries. [ABSTRACT FROM AUTHOR]

We propose tabular two-dimensional correlation spectroscopy analysis for extracting features from multifaceted characterization data, essential for understanding material properties. This method visualizes similarities and phase lags in structural parameter changes through heatmaps, combining hierarchical clustering and asynchronous correlations. We applied the proposed method to data sets of carbon nanotube (CNT) films annealed at various temperatures and revealed the complexity of their hierarchical structures, which include elements such as voids, bundles, and amorphous carbon. Our analysis addresses the challenge of attempting to understand the sequence of structural changes, especially in multifaceted characterization data where 11 structural parameters derived from eight characterization methods interact with complex behavior. The results show how phase lags (asynchronous changes from stimuli), and parameter similarities can illuminate the sequence of structural changes in materials, providing insights into phenomena such as the removal of amorphous carbon and graphitization in annealed CNTs. This approach is beneficial even with limited data and holds promise for a wide range of material analyses, demonstrating its potential in elucidating complex material behaviors and properties. [ABSTRACT FROM AUTHOR]

At present, graphite is commonly used as the carbon source in Al2O3‐C refractory. However, graphite resources are limited and belong to the category of nonrenewable resources. Coconut shell is a biomass material with low cost, low impurity, and high reactivity, and also belongs to renewable resources. Therefore, the research for using coconut shell carbon as a substitution for graphite in Al2O3‐C refractory has great significance. In this work, the coconut shell was firstly carbonized at 200–1000°C in flowing argon, and the microstructure of the carbonized coconut shells was investigated. Then the carbonized coconut shell powder was introduced into Al2O3‐C refractory instead of graphite, and the effect of carbonized coconut shell on mechanical properties and microstructure evolution of materials was investigated. The results show that the carbonized coconut shell has porous structures, composed of amorphous carbon and disordered micro‐graphite with many defects, endowing its high reactivity. Compared with graphite, the carbonized coconut shell promotes the Si and Al to in situ formation of nonoxide ceramic whiskers (SiC, Al4C3, and AlN), which play a strengthening and toughening role in the materials. When graphite is replaced by 1 wt% carbonized coconut shell, the residual strength ratio of samples increased from 81.8% to 90.2%, and that of the hot modulus of rupture increased from 17.53 MPa to 18.47 MPa. [ABSTRACT FROM AUTHOR]

A Li‐ion battery combines a cathode benefitting from Sn and MnO2 with high sulfur content, and a lithiated anode including fumed silica, few layer graphene (FLG) and amorphous carbon. This battery is considered a scalable version of the system based on lithium‐sulfur (Li−S) conversion, since it exploits at the anode the Li‐ion electrochemistry instead of Li‐metal stripping/deposition. Sn and MnO2 are used as cathode additives to improve the electrochemical process, increase sulfur utilization, while mitigating the polysulfides loss typical of Li−S devices. The cathode demonstrates in half‐cell a maximum capacity of ~1170 mAh gS−1, rate performance extended over 1 C, and retention of 250 cycles. The anode undergoes Li‐(de)alloying with silicon, Li‐(de)insertion into amorphous carbon, and Li‐(de)intercalation through FLG, with capacity of 500 mAh g−1 in half‐cell, completely retained over 400 cycles. The full‐cells are assembled by combining a sulfur cathode with active material loading up to 3 mg cm−2 and lithiated version of the anode, achieved either using an electrochemical pathway or a chemical one. The cells deliver at C/5 initial capacity higher than 1000 mAh gS−1, retained for over ~40 % upon 400 cycles. The battery is considered a promising energy storage system for possible scaling‐up in pouch or cylindrical cells. [ABSTRACT FROM AUTHOR]

In pulsed laser deposition, along the traditionally exploited deposition on the front‐side of the plasma‐plume, a coating forms on the surface of the target as well. For reproducibility, this residue is usually cleaned and discarded. Here we instead investigate the target‐side coated materials and employ them as a binder‐free supercapacitor electrode. The ballistic‐aggregated, target‐side nanofoam is compact and features a larger fraction of sp2‐carbon, higher nitrogen content with higher graphitic‐N and lower oxygen content with fewer COOH groups than that of diffusive‐aggregated conventional nanofoams. They are highly hydrogenated graphite‐like amorphous carbon and superhydrophilic. The resulting symmetric micro‐supercapacitor delivers higher volumetric capacitance of 522 mF/cm3 at 100 mV/s and 104 % retention after 10000 charge‐discharge cycles over conventional nanofoam (215 mF/cm3 and 85 % retention) with an areal capacitance of 134 μF/cm2 at 120 Hz and ultrafast frequency response. Utilizing the normally discarded target‐side material can therefore enable high performing devices while reducing waste, cost and energy input per usable product, leading towards a greater sustainability of nanomaterials synthesis and deposition techniques. [ABSTRACT FROM AUTHOR]

The exceptional benefits of structural defects and doped atoms in carbon network regarding electromagnetic properties inspire the design of advanced carbon‐based microwave absorption (MA) materials. However, excessive structural defects decline the physical properties of materials, especially their conductivity. Therefore, it is a great challenge to balance structural defects and doped atoms to optimize conductive behavior for carbon‐based MA materials. The spiral carbon nanocoil (CNC), with coexisting amorphous and polycrystalline carbon structures and moderate conductivity, has significant MA properties but lacks pores and doped atoms. Herein, the amorphous carbon parts with relatively weak C─C bond energies are preferentially oxidized at 500 °C in air atmosphere to create pores and combine O atoms in the bodies of CNCs. Furthermore, the mechanism prioritizing the formation of O doping over defects is discovered. Benefiting from the synergistic interplay of structural defects and O dopants, the O‐enriched porous CNCs demonstrate enhanced conduction and polarization losses than the pure CNCs, realizing a wide effective absorption bandwidth of 7.3 GHz at a filling ratio of only 3 wt.%. Theoretical calculations further support these experimental results. The combination of structural defects and doped atoms may serve as an effective pathway for unlocking tunable dielectric properties of carbon‐based materials. [ABSTRACT FROM AUTHOR]

In this work, a novel polymer precursor for yttrium modified hafnium carbide (HfC) was prepared by blending polyhafnium carboxane, yttrium acetylacetonate with xylene. The pyrolysis behavior and structural evolution of the precursor were comprehensively investigated, along with a thorough examination of the microstructure and composition of the synthesized HfC particles. The results showed that Y element was introduced into the ceramics to form c‐HfO2, with Hf, Y, C and O elements well distributed. The pyrolysis of the polymer precursor at 1600°C produced HfC nanocrystallites with an average grain size of 43 nm, encapsulated by an amorphous carbon shell. The synthesized HfC ceramics exhibited distinct nanostructures that varied from amorphous structure to almost spherical morphology under different pyrolysis temperatures. The underlying formation mechanisms were also discussed. [ABSTRACT FROM AUTHOR]

The metastable phase molybdenum carbide-based (α-MoC 1-x) catalysts stand out as a class of the most promising representatives among the non-sulfide catalysts for the synthesis of higher alcohols (HAS) from syngas (CO/H 2) due to their noble metal-like characteristics, resistance to coking, sulfur tolerance and weak C–O bond dissociation. However, the synthesis of α-MoC 1-x commonly involves temperature-programmed ammonification and carburization (TPAC) or the consumption of noble metals. The α-MoC 1-x prepared by TPAC usually exhibited large particle size, low dispersion and poor catalytic performance. Herein, we developed a facile and continuous thermal plasma method for synthesizing nanosized α-MoC 1-x , which was highly dispersed on amorphous carbon (α-MoC 1-x /C-Pla). Compared with the α-MoC 1-x prepared by TPAC method (α-MoC 1-x -TPAC), the α-MoC 1-x /C-Pla catalyst exhibited higher CO conversion and excellent stability. The high dispersion and reactant adsorption/desorption capacity of α-MoC 1-x /C-Pla contributed to its high catalytic activity, while the anti-aggregation property of the nanosized α-MoC 1-x in α-MoC 1-x /C-Pla conferred the high stability for the α-MoC 1-x /C-Pla catalyst. [Display omitted] • A facile and continuous method for synthesizing α-MoC 1−x /C-Pla was developed. • Nanosized α-MoC 1−x particles were well dispersed on carbon in α-MoC 1−x /C-Pla. • α-MoC 1−x /C-Pla exhibited high activity and stability for syngas to higher alcohols. [ABSTRACT FROM AUTHOR]

Sodium metal anodes (SMA), featuring high energy content, low electrochemical potential and easy availability, are a compelling option for sustainable energy storage. However, notorious sodium dendrite and unstable solid‐electrolyte interface (SEI) have largely retarded their widespread implantation. Herein, porous amorphous carbon nanofiber embedded with Bi nanoparticles in nanopores (Bi@NC) was rationally designed as a 3D host for SMA. In situ and ex situ characterizations, along with theoretical simulations unlock that the in‐situ formed Na−Bi alloy significantly accelerates sodium metal nucleation and sodium ion diffusion kinetics, enabling uniform sodium plating within the void spaces and a stable SEI outside the carbon nanofiber. Particularly, the Bi@NC electrode achieved a high coulombic efficiency of 99.99 % at 3 mA cm−2 and 3 mAh cm−2 in half‐cell tests, a cycle life of 1000 hours at 5 mA cm−2 and 10 mAh cm−2, and sustained performance over 600 cycles under harsh conditions under 30 mA cm−2 and 3 mAh cm−2 within symmetrical cells. The full battery assembled with a Na3V2(PO4)3@C cathode and Bi@NC anode delivered long‐term cyclability over 800 cycles, demonstrating its potential for flexible application of sodium‐based energy storage systems. This work highlights the Bi@NC electrode as a promising candidate for high‐performance and flexible sodium metal batteries. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (NIBs) are gaining momentum, thanks to the increasing demand for energy storage devices and the abundant reserves and low sodium cost. Transition metals are well‐established materials due to their high conductivity and electrochemical activity. In this work, metal selenides (MSex) (M: Ni, Co, Fe) are obtained by facile selenization in a single step of transition gallic acid based metal organic frameworks (MOFs) under Ar flow at 600 °C. As the powders undergo selenization, the resulting MSex particles are encapsulated within the amorphous carbon network formed by the decomposition of the gallate ligand. The microstructures are examined by HR‐TEM analyses and the characteristic interplanar spacing of each transition metal selenide is measured and found to coincide with the XRD pattern. Meanwhile, the specific surface areas were measured as 121, 152, and 155 m2/g for CoSe2, NiSe and FeSe, respectively. The resulting NiSe/C, CoSe2/C and FeSe/C nanomaterials are tested as NIB negative electrodes and are shown to have a capacity of 315, 312, and 363 mAh/g, respectively, after 100 cycles at a current density of 100 mA/g while Na‐ion diffusion coefficients (DNa+) are calculated in the range of 10−10–10−7 cm2/s by galvanostatic intermittent titration (GITT) technique. [ABSTRACT FROM AUTHOR]

The catalyst is the pivotal component in CO2 electroreduction systems for converting CO2 into valuable products. Carbon-based single-atom materials (CSAMs) have emerged as promising catalyst candidates due to their low cost and high atomic utilization efficiency. The rational design of the morphology and microstructure of such materials is desirable but poses a challenge. Here, we employed different Mg(OH)2 templates to guide the fabrication of two kinds of amorphous nitrogen-doped carbon nanosheet-supported Fe single atoms (FeSNC) with rough and flat surface structures. In comparison to flat FeSNC with saturated FeN4 sites, the rough FeSNC (R-FeSNC) exhibited unsaturated FeN4−x sites and contracted Fe-N bond length. The featured structure endowed R-FeSNC with superior capacity of catalyzing CO2 reduction reaction, achieving an exceptional CO selectivity with Faradaic efficiency of 93% at a potential of −0.66 V vs. RHE. This study offers valuable insights into the design of CSAMs and provides a perspective for gaining a deeper understanding of their activity origins. [ABSTRACT FROM AUTHOR]

[Display omitted] Microstructural engineering is regarded as a promising option for fabricating high-performance carbon anodes. Hence, a facile solvothermal-assisted low-temperature calcination strategy was employed to modulate the microstructure of semicoke-derived carbon anodes. Owing to the effective pseudo-graphite phase modulation, the modified carbon anode exhibited a significant increase in capacity, cycling stability and ion kinetics in both lithium-ion batteries and sodium-ion batteries. Kinetic analysis and in-situ X-ray diffraction confirmed the "adsorption and intercalation" energy storage mechanism of the obtained carbon electrodes. In addition, by investigating the energy storage mechanism, we found that increasing the pseudo-graphite phase proportion played different roles in lithium and sodium ions storage. For lithium-ion storage, the pseudo-graphitic phase preferentially promotes lithium-ion transport kinetics. Conversely, during sodium-ion storage, this particular structure markedly augments the embedding capacity of sodium. Theoretical calculations demonstrate that different patterns of variation in the activation energy with the carbon layer spacing of lithium/sodium intercalation compounds lead to differences in performance enhancement. This study not only offers a low-cost approach for preparing carbon anodes enriched with a pseudo-graphitic phase, but also provides new insight into the discrepancy between lithium ion and sodium ion storage. [ABSTRACT FROM AUTHOR]

[Display omitted] Balancing the bicatalytic activities and stabilities between oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a critical yet challenging task for exploring advanced rechargeable Zinc–air batteries (ZABs). Herein, a hybrid nanosheet catalyst with highly dispersed and densified metallic species is developed to boost the kinetics and stabilities of both ORR and OER concurrently. Through a progressive coordination and pyrolysis approach, we directly prepared highly conductive onion-like carbon (OLC) accommodating dense ORR-active Co N C species and enveloping high-loading OER-active CoNi-synergic structures within a porous lamellar architecture. The resultant CoNi/OLC nanosheet catalyst delivers better ORR and OER activities showcasing a smaller reversible oxygen electrode index (Δ E = E j10 − E 1/2) of 0.71 V, compared to state-of-the-art Pt/C-RuO 2 catalysts (0.75 V), Co/amorphous carbon polyhedrons (0.80 V), NiO nanoparticles with higher Ni loading (1.00 V), and most CoNi-based bifunctional catalysts reported so far. The rechargeable ZAB assembled with the developed catalyst achieves a remarkable peak power density of 270.3 mW cm−2 (172 % of that achieved by Pt/C + RuO 2) and ultrahigh cycling stability with a negligible increase in voltage gap after 800 h (110 mV increase after 200 h for a Pt/C + RuO 2 -based battery), standing the top level of those ever reported. [ABSTRACT FROM AUTHOR]

In this work, we report the x-ray photoelectron spectroscopy characterization of a novel nanocomposite (photo)electrocatalyst for the oxygen evolution reaction, based on amorphous carbon nitride (aCN) functionalized with CuxO nanoparticles (NPs). The specimen has been fabricated employing two sequential plasma-assisted processes, involving the initial aCN deposition onto conductive glass via magnetron sputtering, followed by carbon nitride functionalization with CuxO (x = 1, 2) NPs by radio frequency-sputtering. The results reported herein include the survey spectrum and the high-resolution C 1s, N 1s, O 1s, Cu 2p, and Cu LMM signals. The most significant spectral features are analyzed and critically discussed. [ABSTRACT FROM AUTHOR]

Studies pertaining to the evaluation of temperature rise in bio-tribopairs are scarce. The present work analyses the application of Si-doped amorphous carbon (Si:a-C) and carbon-fibre-reinforced-PEEK (CFRPEEK) as a potential metal-on-polymer acetabular articulation. The structure of the materials was studied using XRD and Raman spectroscopy and the mechanical behaviour of the Si:a-C film was evaluated using nanoindentation test and Rockwell-C indentation test. Si incorporation resulted in improved hardness and elastic modulus of a-C film along with appreciable H/E and H3/E2 attributes. The structure of Si:a-C film presented SiC phase with reduced sp2 clustering which results in lower graphitisation. CFRPEEK showcased crystalline structure with disorderness induced due to the introduction of carbon fibre. What is more, during lubricated sliding, the temperature rise in the sliding interface was obtained using thermocouple installed in the CFRPEEK counterbody near the sliding vicinity. The results showed low friction coefficient due to the formation of SiOx phase during sliding with low temperature rise having coefficient of 2.1. Si:a-C film underwent low fracture with patches of delamination and CFRPEEK suffered fibre pull-out and tearing. Further studies on the biological activities such as cell adhesion and bacterial adhesion can mainstream the application of these materials for implants. [ABSTRACT FROM AUTHOR]

Herein, gold nanoparticle-decorated amorphous carbon (Au/AC) was prepared by reducing chloroauric acid and layering it on amorphous carbon. The characteristics of Au/AC were examined using FT-IR, XRD, TGA, SEM, EDS, and XPS. To assess its catalytic activity, Au/AC was tested in a reaction involving anthranilamide and benzyl alcohol at 110 °C for 24 hours. This reaction yielded various 2-phenylquinazolin-4(3H)-one derivatives in moderate to good yields (44–80%). Furthermore, control experiments were conducted to demonstrate the oxidation and cyclization functions of Au/AC. Noteworthy aspects of this approach included the ease of isolating Au/AC (via recrystallization) and the ability to recycle it. [ABSTRACT FROM AUTHOR]

In this investigation, blue-emitting carbon nanodots (B.CNDs) with exceptional color purity were successfully synthesized from fresh fig fruit using a one-step pyrolysis method. These B.CNDs are small and spherical (3.7 nm) with an amorphous carbon core encapsulated inside a passivated layer primarily composed of oxygen-related functional groups. They demonstrated an emission property that is independent of excitation, showing the highest emission intensity in the deep blue region at 450 nm with a narrow full-width at half maximum (FWHM) at 44 nm and a quantum yield of 15.5%. This exceptional value of FWHM is attributed to the remarkable uniformity in both morphological and chemical composition that was achieved through the utilization of the reverse diffusion technique combined with the dialysis method for purification and separation of B.CNDs. This work not only contributes to the expanding field of carbon nanomaterials but also introduces a novel and sustainable approach to fabricate CDs with unparalleled color purity and optical performance. [ABSTRACT FROM AUTHOR]

In proton exchange membrane fuel cells (PEMFCs), the interfacial contact resistance (ICR) of amorphous carbon (a-C) coated metallic bipolar plates (BPs) increased with the passage of time, thereby severely limiting their widespread application. The performance of a-C coated BPs was considerably influenced by interface-induced degradation, which in turn was highly sensitive to sp2/sp3, size of sp2 clusters, and compactness of a-C. These factors were closely linked to the underlying metal transition layers and dependent on the deposition temperature. Therefore, in order to elucidate the impact of interface structure on their performance, a series of a-C coatings with Cr transition layer were magnetron sputtered onto 316L stainless steel at temperatures ranging from room temperature (R.T.) to 400 °C. The results revealed that as the deposition temperature increased, the a-C coatings became more porous and exhibited columnar growth characteristics attributed to the hill-like interface structures of the Cr transition layer. Additionally, both the sp2 content and cluster size of a-C increased. Correspondingly, the initial ICR decreased from 2.89 Ω cm2 at R.T. to 1.62 Ω cm2 at 400 °C. Furthermore, in long-term corrosion tests, both the ICR after corrosion and metal ion concentrations in the corrosion solution rose rapidly. Notably, the a-C coating deposited at 100 °C showed the lowest corrosion current density of 5.81 × 10−4 μA/cm2 and the smallest increase rate (65.9%) of ICR after the long-term electrochemical corrosion test, owing to its high sp2 content and dense structure. • Sp2 cluster size of a-C films were separately controlled by deposition temperature. • Increasing sp2 clusters size significantly reduced the initial ICR of a-C films. • XRR analysis revealed the decrease in film compactness with temperature increment. • Loose structure deteriorated the corrosion resistance of a-C in simulated PEMFC environment. [ABSTRACT FROM AUTHOR]

As a kind of ultra-high temperature ceramic, TaC is widely used in aerospace field. In order to improve its high temperature oxidation resistance, SiC is usually added as a second phase. TaC-SiC nanocomposites prepared by precursor-derived ceramic method have the advantages of low pyrolysis temperature, small particle size and uniform phase composition. Some studies have used solid polycarbosilane (PCS) as the precursor of SiC. However, it has problems such as high cost and need to add solvent. In this work, TaC-SiC nanocomposites were prepared by precursor-derived ceramic method with polytantaloxane (PTO) and vinyl-containing liquid polycarbosilane (LPVCS) instead of PCS as raw materials after 2 h pyrolysis at 1600 °C. The obtained TaC-SiC nanocomposites have a particle size of about 200 nm and a grain size of 15–40 nm, wrapped by 1–2 nm amorphous carbon shells, which is beneficial to inhibit grain growth. By analyzing the oxidation mechanism of TaC-SiC nanocomposites, it was found that higher SiC content was conducive to antioxidant, because the SiO 2 protective layer formed by oxidation insulated O 2 diffusion. [ABSTRACT FROM AUTHOR]

An MgH2–anthraquinone carbonization product composite (denoted as MgH2–ACP composites) was successfully prepared through a hydrogenation combustion and mechanical ball-milling method using the original Mg powder to simultaneously achieve modification via in situ-formed amorphous carbon. The amorphous carbon derived from the combustion of carbonic compounds significantly enhanced the hydrogen-absorption and -desorption performances of MgH2. Results revealed that the onset decomposition temperature of the MgH2–ACP composite decreased from 638 K to 587 K in the dehydrogenation stage. Moreover, the MgH2–ACP sample delivered dehydrogenation capacities of 3.525 wt% at 598 K, whereas the as-milled MgH2 decomposed only 0.763 wt% at the same temperature. The activation energies calculated using Kissinger analysis in the dehydrogenation process of MgH2 were lowered by about 57.5 kJ mol−1. For the absorption kinetic measurements at 473 K, the MgH2-ACP sample could uptake about 4.629 wt% of H2 in 3200 s compared to 1.804 wt% taken up by the as-milled MgH2. The in situ-formed amorphous carbon and MgO were confirmed as the active species that contributed to the enhancement of hydrogen-storage properties of the composite. [ABSTRACT FROM AUTHOR]

Surface roughness control of end products is increasingly becoming significant, especially with the miniaturization trends in the semiconductor industry. Ultra-thin amorphous carbon (a-C) films offer a prime solution to optimize surface roughness due to their outstanding characteristics. In this study, hydrogenated a-C films are deposited on two-dimensional quartz plates and three-dimensional quartz molds to evaluate the growth mechanisms and changes in the surface roughness, which is supported by molecular dynamics simulations. Results reveal that surface roughness encounters multiple variations until it reaches stable values. These fluctuations are categorized into four different stages which provide a concrete understanding of various growing mechanisms at each stage. Different behavior of the atoms in the top layers is recorded in the cases of normal and grazing incidents of carbon atoms. Lower surface roughness values are obtained at low-angle deposition. Interestingly, surface smoothing is attained on the sidewalls of the nanotrench mold where the deposition occurs with high incident ion angles. [ABSTRACT FROM AUTHOR]

The development of cost-effective, scalable, and non-precious based bifunctional catalysts that can efficiently catalyze the sluggish oxygen and hydrogen evolution reactions (OER and HER) in the highly corrosive seawater medium is challenging, yet vital to realize a practical seawater electrolyzer. In this work, we demonstrate a nickel-exchanged zeolitic imidazolate framework (Ni@ZIF67)-derived nickel-cobalt-cobalt oxide nanoparticles embedded amorphous carbon (Ni–Co–CoO@C) nanocomposite as an efficient, chloride-resistant, and stable bifunctional catalyst in alkaline seawater. The OER and HER activities are meticulously characterized by comparing nanocomposites prepared at different pyrolysis temperatures. Ni@ZIF67 pyrolyzed at 700 °C (NZ700) exhibits the lowest OER overpotential (281 mV @ 10 mA cm−2) whereas that pyrolyzed at 500 °C reveals the lowest HER overpotential (196 mV @ 50 mA cm−2) in alkaline seawater. The NZ700||NZ700 cell also exhibits the lowest overall splitting voltage in alkaline seawater (1.72 V @ 20 mA cm−2). Detailed post-electrolysis studies are also carried out to explore the origin of the electrocatalytic activities. Furthermore, a zero-gap, flow-cell type alkaline seawater electrolyzer prototype has been fabricated to demonstrate the viability of our catalysts. An easy-to-prepare, scalable, and cost-effective bifunctional catalyst that can split alkaline seawater to produce hydrogen is reported. It exhibits low overall splitting voltage and overpotentials, high stability, and excellent chlorine resistance. [Display omitted] • An efficient bifunctional catalyst for alkaline seawater splitting is reported. • Synthesized by a simple, one-step pyrolysis of Ni-exchanged ZIF67. • Exhibits low OER/HER overpotentials and excellent chlorine-resistance in seawater. • Exhibits low overall seawater splitting voltage (1.72 V at 20 mA cm−2). • The catalyst performance is validated in a zero-gap seawater electrolyzer. [ABSTRACT FROM AUTHOR]

The low capacity, poor cycling life, and rapid self‐discharge hinder the development of carbonaceous dual‐ion batteries (DIBs). Conventional preparations of element doping amorphous carbons are cumbersome, complex, and difficult to control the doping element, content, and size. Here, a nitrogen‐oxygen co‐doped amorphous carbon nanomaterial (NDC) with unique 3D vortex‐layered amorphous structure and high doping content is ingeniously prepared via self‐assembly of hydrogen‐bonded organic framework precursors followed by one‐step pyrolysis, and then used for anodes of DIBs. By pairing with a commercial Nylon separator, a self‐supporting independent graphite cathode, and a high‐concentration electrolyte, the NDC‐based DIBs display an ultra‐high specific discharge capacity of up to 519 mAh g−1 at 1 C, low self‐discharge rate of 0.85% h−1, capacity retention of 98.8% after 1500 cycles, and fast kinetic dynamics. This study offers a novel approach to enable carbonaceous nanomaterials for energy‐dense and long‐cycling DIBs. [ABSTRACT FROM AUTHOR]

Owing to the unique features of high chemical and photostability, structurally colored materials can potentially replace organic dyes and pigments in many applications. The most common fabrication method of structural color materials is the “bottom‐up” self‐assembly approach. However, the assembled structures are easily damaged by external forces, leading to color fading or even disappearance. Therefore, it is still a challenge to fabricate structural colors that mimic the appearance of absorbing pigments without assembly processes. Inspired by the Steller's jay, non‐iridescent structurally colored nanopigments are created, which are composed of hollow SiO2 (H‐SiO2) microspheres with amorphous carbon on the inner wall of the shell and disordered metasurfaces on the shell layer. It is shown that the color originates from the synergistic effect of the disordered metasurfaces and the amorphous carbon layer, which can produce strong coherent scattered light and effectively absorb incoherently scattered light, respectively. Amazingly, the H‐SiO2 microspheres can maintain their structural colors even after grinding or being dispersed in water. What's more, through the additive color mixing of two base colors and precise tuning of their ratios, gradient structural colors that spanning the visible spectrum can be achieved. These features indicate promising prospects for the designed nanopigments. [ABSTRACT FROM AUTHOR]

An MgH2–anthraquinone carbonization product composite (denoted as MgH2–ACP composites) was successfully prepared through a hydrogenation combustion and mechanical ball-milling method using the original Mg powder to simultaneously achieve modification via in situ-formed amorphous carbon. The amorphous carbon derived from the combustion of carbonic compounds significantly enhanced the hydrogen-absorption and -desorption performances of MgH2. Results revealed that the onset decomposition temperature of the MgH2–ACP composite decreased from 638 K to 587 K in the dehydrogenation stage. Moreover, the MgH2–ACP sample delivered dehydrogenation capacities of 3.525 wt% at 598 K, whereas the as-milled MgH2 decomposed only 0.763 wt% at the same temperature. The activation energies calculated using Kissinger analysis in the dehydrogenation process of MgH2 were lowered by about 57.5 kJ mol−1. For the absorption kinetic measurements at 473 K, the MgH2-ACP sample could uptake about 4.629 wt% of H2 in 3200 s compared to 1.804 wt% taken up by the as-milled MgH2. The in situ-formed amorphous carbon and MgO were confirmed as the active species that contributed to the enhancement of hydrogen-storage properties of the composite. [ABSTRACT FROM AUTHOR]

Au@C core–shell nanostructures (Au@C-NS) were synthesized through a low-temperature seed-assisted hydrothermal approach using glucose as carbon source. The material characterization and chemical analysis confirm that the synthesis method allows to obtain uniform core–shell nanostructures constituted by a crystalline metal core and an amorphous carbon shell. Depending on the synthesis conditions, their average size ranges from 146 nm to 342 nm with relative standard deviation as low as 7 %. It is proposed that the characteristic monodispersity results due to a high nucleation rate of the carbon phase at the liquid–solid interface. The obtained monodisperse Au@C-NS were used to prepare water-based nanofluids with superior heat transport properties. The thermal lens analysis shows that the thermal diffusivity of Au@C nanofluids is 9.5 % and 31.3 % higher than their Au nanofluids counterparts and pure water, respectively, at particle concentration of 285 × 1011 ml−1. Phonon-related interactions at the metal cores and carbon shells interfaces are proposed as the heat transport mechanism behind the thermal diffusivity enhancement of the Au@C water-based nanofluids. [ABSTRACT FROM AUTHOR]