Search Results (2,569)

Bearing-grade PEEK composites are intended to improve sliding performance, but filler addition does not necessarily reduce friction. This study compared the dry sliding tribological behaviour of neat PEEK and hybrid PEEK containing PTFE, graphite, and carbon fibre against 42CrMo4+QT steel. Ring-on-block tests were performed at nominal PV values of 0.3–3.2 MPa·m/s, contact pressures of 0.87–5.82 MPa, and sliding velocities of 0.26–0.55 m/s. Each material–condition combination was tested using three independent specimens. Coefficient of friction was calculated from simultaneously measured tangential and normal forces, and subsurface temperature was recorded continuously. Initial and post-test surfaces were examined using optical and extended depth-of-field microscopy. Group mean COF values ranged from 0.052 to 0.123. Hybrid PEEK exhibited a higher numerical mean COF than neat PEEK in all six operating conditions, with relative differences of approximately 1.53–8.36%. Two-factor ANOVA estimated an overall hybrid-minus-neat difference of +0.003388 COF units (95% CI 0.001279–0.005496; p = 0.0029), whereas none of the six condition-specific neat–hybrid comparisons was significant after Holm correction. Initial temperature, maximum temperature, and baseline-normalised temperature rise were reported for every specimen and treated descriptively. Both materials reached stable sliding states without seizure or uncontrolled thermal escalation. Post-test EDF observations showed a denser pattern of fine grooves on neat PEEK, whereas hybrid PEEK exhibited comparatively smoother intervening regions interrupted by fewer but locally deeper features. Mass changes remained close to the capability of the applied balance and did not permit quantitative wear-rate comparison. The results show that the investigated hybrid formulation did not provide a dry-friction reduction advantage over neat PEEK under the tested conditions. Full article

Regional metamorphic graphite deposits in the North China Craton (NCC) are important crystalline graphite resources, but the links among sedimentary protolith, metamorphic evolution, and graphite mineralization remain insufficiently constrained in many ore belts. In the Datong–Xinrong graphite belt of northern Shanxi Province, the studied ore is hosted by graphite-bearing gneiss of the Paleoproterozoic Huangtuyao Formation. The graphite-bearing rocks are interpreted as mudstone-derived paragneiss and contain graphite, plagioclase, quartz, biotite, diopside, garnet, alkali feldspar, pyrrhotite, and minor sillimanite. To clarify the ore-controlling factors and metallogenic evolution of these rocks, we integrated whole-rock geochemistry, Raman spectroscopy of carbonaceous material (CM), and zircon U-Pb geochronology. Geochemical indicators and discrimination diagrams show that the protolith was deposited in a continental-margin setting under dry, brackish-water, and generally oxygen-rich conditions. Raman CM thermometry yields peak metamorphic temperatures of 445.9–534.0 °C, and mineral assemblage constraints indicate pressures of 6.10–7.13 kbar. Zircon U-Pb ages constrain the maximum depositional age of the sedimentary protolith to 2102 ± 42 Ma and the age of mineralization-related metamorphism to 1888 ± 25 Ma. These results support a sedimentary–metamorphic model in which carbon-bearing mudstone was deposited along an early Paleoproterozoic continental margin and was later transformed into graphite-bearing gneiss during late Paleoproterozoic orogenic metamorphism. Full article

Biomass-derived nanoengineered carbon materials have emerged as key platforms in environmental technologies due to their high surface area, electrical conductivity, chemical stability, and sustainable synthetic route starting from renewable feedstock. This broad family comprises dimensionally nanoscale materials, such as carbon dots, carbon nanofibers, and graphene-based structures, as well as biochars, hydrochars, activated carbons, and related porous carbonaceous materials whose pore architecture, surface chemistry, or defects are deliberately engineered at the nanometer scale. Beyond their traditional role as passive supports, these materials can actively regulate adsorption phenomena, charge transport, and catalytic microenvironments through precise control of heteroatom doping, graphitic domains, and hierarchical porosity. Among current environmental priorities, carbon dioxide (CO₂) management represents one of the most pressing challenges. Biomass-derived nanocarbons offer tunable adsorption sites for selective CO₂ capture while simultaneously serving as active matrices for catalytic conversion. Tailored doped-carbon frameworks can stabilize key reaction intermediates, suppress competing pathways such as hydrogen evolution, and promote selective transformation into fuels and high-value chemicals. In addition, these materials are excellent hosts for atomically dispersed metals, dual-site catalysts, and semiconductor hybrids used in electrochemical and photocatalytic CO₂ reduction. By combining renewable sourcing with nanoscale control of reactivity, carbon materials create a bridge between environmental remediation and carbon valorization. This review critically examines recent progress in biomass-derived nanoengineered carbon materials for integrated CO₂ capture and conversion, with emphasis on structure-property-performance relationships, mechanistic roles, scalability, and sustainability. Particular attention is also devoted to catalytic conversion and electrochemical CO₂ sensing, where carbon-based and hybrid interfaces enable the transduction of CO₂ recognition into measurable electrical responses. These materials represent a promising yet underexplored pathway toward circular carbon management and the development of next-generation low-carbon chemical technologies. Full article

Sustainable management of antibiotic fermentation residues is critical to mitigating environmental and public health risks associated with pharmaceutical waste. Gentamicin fermentation residue (GFR), a challenging antibiotic byproduct rich in nitrogen and organic matter, presents both environmental risks and untapped resource potential. Pyrolysis can convert GFR into high-value products (pyrolysis oil, gas, and char) and eliminate environmental risks through high-temperature treatment. In this study, the product yields, pyrolytic kinetics, and nitrogen transformation pathways at different temperatures (400–800 °C) were investigated to explore the pyrolysis behavior and mechanism of GFR. Results revealed that temperature strongly influenced product distribution: biochar yield was dominant at low temperatures 51.2 ± 0.4% at 400 °C, oil yield peaked at 600 °C 14.6 ± 0.4%, and gaseous products became prevalent above 700 °C, reaching an estimated 78.4 ± 0.2% at 800 °C by mass-balance difference. Furthermore, isoconversional kinetic analysis (FWO and KAS) yielded apparent activation energies of 226.9–249.4 kJ/mol over α = 0.5–0.8, with R² values of 0.946–0.976, indicating conversion-dependent, multi-step devolatilization behavior. For nitrogen transformation, elemental and spectroscopic analyses showed that nitrogen transitioned from unstable pyrrolic forms in raw GFR to more stable pyridinic and graphitic forms in biochar, enhancing its potential for catalytic and environmental applications. Meanwhile, gaseous nitrogen species such as NH₃ and HCN were released at different temperature stages, and a three-stage nitrogen transformation mechanism was proposed linking the decomposition kinetics to the nitrogen migration pathways. These findings highlight pyrolysis as a promising, controllable, and sustainable method to convert antibiotic residues into valuable energy products and functional materials, with its contribution to sustainable pharmaceutical waste management contingent on proper NH₃/HCN gas treatment. Full article

Traditional petroleum coke-based porous carbons suffer from low specific surface area, insufficient surface active sites, and inferior rate and cycling performance. Herein, a series of sulfur/fluorine-co-doped hierarchical porous carbon (S+F-PC) cathode materials were synthesized controllably from industrial solid-waste petroleum coke via KOH high-temperature activation and heteroatom doping strategies. Polyaniline/carbon nanotube (PANI/CNTs) core–shell composites were fabricated as anodes through in situ oxidative polymerization, and S+F-PC//PANI/CNT asymmetric aqueous supercapacitors were assembled. The structural and chemical modulation mechanisms of dual heteroatom doping, as well as the electrochemical energy storage kinetics of electrodes and devices, were systematically investigated using SEM, TEM, XRD, XPS, BET, CV, GCD, EIS, and long-cycle tests. The results verify the synergistic modification effect of sulfur and fluorine co-doping. S-induced lattice distortion creates abundant mesopores and pseudocapacitive active sites, while F atoms stabilize the carbon skeleton to avoid high-temperature structural collapse and enhance the graphitization degree. The optimized S+F-PC exhibits an interconnected micropore–mesopore–macropore hierarchical network and a specific surface area of 172.2 m²/g, delivering a high specific capacitance of 477 F/g at 1 A/g, outperforming pure PC, and single-S-doped and -F-doped counterparts. The PANI/CNTs core–shell structure effectively alleviates the volume expansion of PANI during cycling, and the one-dimensional CNTs form a continuous conductive network. The PANI/CNT anode achieves a specific capacitance of 417 F/g, with a capacity retention of 91.4%, after 10,000 cycles. The assembled asymmetric supercapacitor realizes a stable voltage window of 1.6 V. It presents a specific capacitance of 117 F/g at 1 A/g, a maximum energy density of 41 Wh/kg at a power density of 2000 W/kg, and 87.2% capacity retention after 10,000 cycles. This work provides a feasible strategy for the high-value recycling of industrial-waste petroleum coke and the design of high-performance heteroatom-doped carbon electrodes and matched asymmetric aqueous supercapacitors. Full article

Integrated electrochemical sensors (IESs) offer rapid and efficient detection of environmental pollutants, but their broader practical implementation requires overcoming common challenges associated with reproducible fabrication and long-term stability. In this work, these challenges were addressed using a thick-film approach to fabricate IESs with graphite-glass, glassy carbon, and carbon black working electrodes (WEs) by screen printing followed by firing at 850 °C. The relationship between the structure of the carbon-based WEs and the electrochemical performance of the IESs was systematically investigated using cyclic voltammetry (CV) in combination with X-ray powder diffraction, transmission electron microscopy (TEM), and scanning TEM. The analyses revealed distinct morphologies and structural ordering of the carbon WEs, which directly affect their electron-transfer kinetics, adsorption behaviour, capacitive response, and electrochemically active surface area. The ordered structure of the graphite-glass WE was associated with lower capacitance and faster electron-transfer kinetics, as determined from the CV response of the IES. In contrast, the disordered structure of the carbon black WE was associated with higher capacitance and slower kinetics of the IES. The glassy carbon-based IES exhibited kinetics similar to those of the carbon black-based IES, but with the lowest capacitance, resulting in the greatest signal definition. Consequently, although all IESs exhibited wide operating potential windows (−1.6 V to +1.0 V vs Ag/AgCl) and fast heterogeneous electron-transfer kinetics towards the [Fe(CN)₆]^3−/4− redox probe (7.6 × 10⁻³–15.5 × 10⁻³ cm s⁻¹), the carbon materials differed in their electrochemical response and signal definition. Importantly, all IESs demonstrated excellent reproducibility (relative standard deviation < 2.4%), operational stability with less than 5% signal loss after 1000 CV cycles, and shelf-life stability exceeding 30 days. These findings demonstrate that tailoring the carbon structure of the screen-printed thick-film WEs enables reproducible fabrication of stable and reliable IESs while providing a versatile strategy for tuning their electrochemical performance towards application-specific requirements. Full article

Hydrogen (H₂) detection under practical operating conditions requires sensing materials that simultaneously provide accessible reaction sites, efficient gas diffusion pathways, and fast interfacial charge transfer. Here, a hierarchical star-sphere ZnCo₂O₄ (ZC) architecture was integrated with graphene oxide (GO) and Pt supported on graphitized carbon (Pt/C) to develop hybrid chemiresistive sensing layers for low-temperature hydrogen detection. The synthesized ZC-based material exhibited a hierarchical morphology consisting of porous microspheres and star-shaped assemblies, providing a multiscale framework for gas access and surface reactions. By varying the GO content from 0.1 to 1 wt% at a fixed Pt/C loading, the ZC-0.5G composite achieved the most balanced structure, with well-distributed GO sheets, preserved star–sphere morphology, the highest specific surface area (53.6 m²/g), and the largest pore volume (0.09 cm³/g). The optimized sensor gave responses of 12.96%, 19.20%, 22.87%, and 26.43% for 500, 4000, 8000 and 10,000 ppm H₂ concentrations, respectively, with measurable response down to 50 ppm. The highest sensing performance was achieved at 50 °C and 60% relative humidity (RH), where the hierarchical oxide framework, GO-assisted interfacial pathways, and Pt catalytic sites acted in concert. The sensor also showed repeatable cyclic behavior and preferential response to H₂ compared to methanol, isopropanol, ethanol, acetone, and dimethylformamide. The improved sensing performance is attributed to the synergistic combination of the hierarchical ZC framework, GO-assisted interfacial pathways, and Pt-assisted catalytic activation, which together facilitate gas diffusion, surface reactions, and resistance modulation. Full article

Accurate specification of spatial heat sources is required for liquid fuel molten salt reactors, given the redistribution of deposited energy among fuel salt, graphite, and metallic structures by gamma ray transport. In this study, a refined power deposition framework based on Monte Carlo particle transport was formulated for a 150 MW thorium molten salt reactor to quantify particle, material, and spatial contributions to the core heat source. The calculation was performed under a static fuel salt approximation, in which flow-induced transport of delayed particle precursors in the circulating fuel salt was not explicitly considered. Particular attention was given to gamma ray generation, transport, and deposition, as well as to the resulting refined power density distribution. The results show that gamma rays contribute 7.64 MW to graphite heating, approximately 3.11 times the neutron contribution. In the alloy sleeve, capture gamma rays account for 63.44% of the deposited power, producing an average power density of 9.34 MW/m³, nearly 18 times that in graphite. This behavior is primarily associated with the strong neutron capture capability of the tungsten bearing alloy and the relatively short gamma ray mean free path in this material. The refined power density distribution further indicates that fuel salt channel power density decreases from about 100.0 MW/m³ near the core center to 57.7 MW/m³ near control rod assemblies, while local graphite power density varies by more than 40%. These findings indicate the need for spatially resolved and material specific heat source descriptions in thermal hydraulic coupling and structural heat load assessment, rather than material averaged treatments or fixed fuel to graphite scaling. Full article

Graphite-based nanocomposites with nitrogen-rich covalent two-dimensional materials are promising for energy, catalytic and sensing applications, but their controlled construction remains challenging because both graphite and many covalent 2D materials consist of stacked sheets that are difficult to integrate homogeneously without prior exfoliation, dispersion, mixing, and restacking. Here, we explore a solvent-free strategy that uses melamine-confined graphite as a preorganized precursor for chemical transformations between graphene layers. We demonstrate that intercalated melamine can undergo reaction pathways analogous to those of bulk melamine, enabling not only the previously reported formation of graphite/g-C₃N₄ composites but also the construction of a new graphite/melem composite. The same concept is further extended to multicomponent solid-state reactions by introducing pyromellitic dianhydride, enabling the formation of new graphite/polyimide-linked two-dimensional material composites from either melamine or melem precursors. Comparison of one-pot and stepwise routes shows that precursor preorganization within graphite improves framework preservation, structural continuity, and morphological homogeneity. Overall, this work presents graphite interlayers as confined reaction environments for transforming simple nitrogen-rich molecules into integrated graphite/2D-material composites, providing a scalable platform for exploring solid-state chemistry and hybrid material synthesis between graphene layers. Full article

Electromagnetic interference (EMI) shielding is essential in modern electronics, telecommunications, and aerospace systems. Graphite-based materials are promising shielding candidates due to their tunable electrical conductivity, low density, corrosion resistance, and thermal stability. However, numerical studies investigating the combined effects of conductivity and thickness on shielding effectiveness (SE) across the X-band remain limited. This study presents a parametric finite element analysis of EMI shielding performance for graphite materials with electrical conductivities of 1, 10, 100, 1000, and 3000 S/m, representing structures ranging from highly porous to dense graphite. Thicknesses from 1 to 10 mm are simulated in a WR90 rectangular waveguide using finite element simulations. The Transition Boundary Condition (TBC) is employed to efficiently model conductive slabs without resolving the skin depth via volumetric meshing. Shielding effectiveness is evaluated from S-parameters and decomposed into total (SET), absorption (SEA), and reflection (SER) components. Results show that SET increases with both conductivity and thickness, and that shielding behavior is strongly dependent on conductivity. Low-conductivity graphite (σ = 1 S/m) exhibits absorption-dominated shielding, reaching an absorbed power fraction of 89% at 5 mm thickness. At σ = 10 S/m, the material enters a transitional regime where absorption and reflection contribute comparably. For highly conductive graphite (σ ≥ 100 S/m), reflection becomes dominant, with the reflected power fraction approaching 0.97 at σ = 3000 S/m. A conductivity-dependent saturation thickness is identified, beyond which additional thickness provides negligible shielding improvement. Dense graphite materials (σ ≥ 1000 S/m) reach saturation at approximately 1 mm thickness. Finally, a conductivity–thickness design heatmap is developed to guide the optimization of graphite-based EMI shielding materials. Full article

Metal-graphitic nanocapsules are an emerging class of metal-graphitic hybrid nanomaterials, typically consisting of a metal core confined within a single- or few-layer graphitic shell. This unique core–shell architecture integrates the tunable physicochemical properties of metal nanomaterials with the chemical stability, Raman activity, fluorescence-quenching capability, and surface functionalization capacity of graphitic materials. In particular, the metal core can provide plasmonic enhancement as well as magnetic or catalytic auxiliary functions, while the chemically protective graphitic shell protects the core from harsh environments and provides intrinsic Raman bands that can serve as internal standards under well-controlled conditions. These features make metal-graphitic nanocapsules highly attractive as robust nanoprobes for molecular spectroscopy-based chemical analysis, biosensing, and targeted diagnosis. In this review, we first summarize the synthesis strategies, formation mechanisms, and key properties of representative metal-graphitic nanocapsules. We then discuss recent advances in their use across representative analytical and biomedical scenarios, with emphasis on the integration of spectroscopic readouts with targeted recognition strategies. Particular attention is given to how the metal core and graphitic shell cooperatively enhance signal generation, molecular enrichment, selective recognition, environmental stability, internal calibration, and reliable in situ diagnosis in real samples and living systems. Finally, we discuss current challenges and future perspectives for developing metal-graphitic nanocapsules as versatile platforms for molecular spectroscopy-based analysis and diagnosis. Full article

The development of indoor photovoltaic devices for powering Internet of Things (IoT) sensors requires low-cost and sustainable components, making dye-sensitized solar cells (DSSCs) an ideal candidate for artificial light harvesting. The counter electrode plays a critical role in transferring electrons and catalyzing the reduction in the redox electrolyte. However, the traditional use of expensive and scarce platinum (Pt) limits the cost-effective, large-scale commercialization of these devices. While carbon-based materials offer a highly porous, conductive, and abundant alternative, commercial carbon pastes frequently require energy-intensive high-temperature sintering. In this study, we propose a sustainable, low-temperature, and screen-printable carbon composite counter electrode (LoT-HPC) using bio-derived hydroxypropyl cellulose (HPC) as a highly effective binder. Rheological characterizations confirm that the formulated LoT-HPC ink possesses an ideal shear-thinning profile and rapid structural recovery, ensuring excellent printability and film homogeneity. By comparing the custom LoT-HPC composite against a commercial high-temperature screen-printed graphite paste (HT-Elco) and a standard sputtered Pt-FTO electrode, we demonstrate the structural and electrocatalytic advantages of this material. When integrated into full DSSC devices and evaluated under low indoor illumination (1000 lux), the LoT-HPC cell delivers a power conversion efficiency (PCE) of 14.8% and a high short-circuit current density of 103.9 µA cm⁻². Furthermore, the custom device demonstrated exceptional operational stability, retaining 98.6% of its initial efficiency (from 14.8% to 14.6%) after 200 h of continuous light-soaking and J-V cycling under 1000 lux. Ultimately, the successful implementation of the HPC binder enables the low-temperature fabrication of sustainable carbon counter electrodes without the need for energy-intensive thermal treatments, presenting a highly scalable pathway for indoor DSSC manufacturing. Full article

The valorization of agricultural waste into high-value carbon nanomaterials offers dual benefits: it reduces pollution and provides low-cost materials for sustainable technologies. This work synthesizes graphene-like carbon from Ghars date waste via mild KOH-assisted pyrolysis at 1000 °C. The material (G-GhW1000) exhibits a sharp (002) XRD peak at 26.16° (d-spacing = 3.40 Å), a characteristic π → π* transition at 253 nm, and a high C/O ratio of 27.37. Dispersed in tap water (0.5 g/L) by simple hand shaking (without ultrasonication), it serves as a photothermal nanofluid in a modified single-slope solar still (MSS). Under outdoor conditions, the MSS produces 4.69 L·m⁻²·day⁻¹, which is 18.7% higher than a conventional still, with thermal efficiency rising from 27.2% to 30.8% (with a reproducible 19.0% enhancement in summer). Samples prepared at 800 °C and 900 °C give 4.0% and 6.4% lower yields, while the 1100 °C sample gives only 6.0% improvement, confirming 1000 °C as the optimal temperature. The superior performance at 1000 °C is attributed to the optimal balance between graphitization, deoxygenation, and structural integrity, as evidenced by XRD, FTIR, EDX and UV-Vis analyses. The enhanced performance is linked to higher water temperature (68 °C) and larger ΔT. The distilled water meets WHO standards (TDS 9.35 mg/L, >99.4% reduction) with no detectable graphene-like carbon carryover. This work demonstrates the potential of waste-derived graphene-like carbon as a low-cost additive for solar desalination, addressing water scarcity and waste management within a circular economy framework. To our knowledge, this is the first study to use Ghars date waste-derived graphene-like carbon in a solar still. Full article

Microbial fuel cells (MFCs) are promising bioelectrochemical systems for converting organic matter into electrical energy, but their practical relevance depends on both functional performance and sustainability-oriented viability. This study evaluated the bioelectrochemical behavior of double-chamber MFCs inoculated with kefir, comparing graphene and graphite anodes under fed-batch operation. A total of 33 MFC series were monitored longitudinally through voltage, current, power output, substrate consumption, and oxidation-reduction potential. Under the LED-connected closed-circuit configuration used here, kefir-inoculated reactors exhibited a reproducible electrical response together with near-complete substrate depletion. These findings support kefir as a workable mixed inoculum for comparative reactor operation under the tested conditions, although direct extracellular electron transfer and exclusive microbial causation of the measured signal were not demonstrated. Graphene showed higher early and mean electrical performance than graphite, particularly in power-related metrics, although this advantage decreased over time and did not result in a categorical separation of final batch-level outcomes. In contrast, substrate consumption remained highly similar between anode materials, indicating that the main material effect was expressed in electrochemical translation rather than in overall substrate conversion. Taxonomic profiling supported the presence of a metabolically complementary consortium dominated by lactic acid bacteria, acetic acid bacteria, Gram-negative bacteria, and yeasts. Deterministic sensitivity analysis and Monte Carlo-based LCA/TEA screening further showed that the most sustainable scenario was not necessarily the one with the highest electrical response, highlighting the importance of integrating performance, material burden, and uncertainty in MFC assessment. Full article

With the rapid development of recycling and secondary utilization of end-of-life battery materials, it is crucial to clarify the impact of full-lifecycle degradation on the thermal safety limits of lithium-ion batteries. This study focuses on a 16 Ah NCM613|graphite pouch battery. First, it analyzes the evolution of capacity decay, thickness expansion, and internal resistance during cycling at room temperature (25 °C) and high temperature (45 °C). Furthermore, an adiabatic accelerated calorimeter (ARC) is employed to investigate the influence of different states of health (SOH) levels (95% and 85%) on the battery’s thermal runaway characteristics. The findings indicate that, macroscopically, batteries in all states follow similar voltage–temperature failure pathways, with mass loss rates confined to a narrow range of approximately 16%, emphasizing the low catastrophic potential of mid-nickel chemistry. However, the microscopic kinetic mechanisms exhibit significant anisotropy: although thickness and internal resistance display no apparent abrupt increase during the late stage of room temperature aging, the capacity exhibits a highly nonlinear plunge behavior. The severe internal lithium plating side reaction triggered by this phenomenon causes the self-heating onset temperature to drop rapidly from 130.0 °C in the fresh state to 79.7 °C. Concurrently, the activation energy of the exothermic side reaction, fitted using a simplified Arrhenius equation, exhibits a non-monotonic variation with aging progress. In the early stages of aging at 95% SOH, due to high temperatures promoting more significant growth of the interfacial film or moderate film formation at room temperature enhancing interfacial thermal stability, the activation energies for both aged batteries increase, and the energy barrier at high temperatures is slightly higher than at room temperature; however, during the deep aging stage at 85% SOH, due to the degradation of active material components and the emergence of lithium plating characteristics, the energy barrier significantly decreases, with high-temperature-aged batteries exhibiting a greater reduction, highlighting the cumulative negative impact of prolonged high-temperature exposure on thermal safety. The research provides a core scientific basis for establishing a battery safety early warning and dynamic health management system covering the entire lifecycle. Full article