Carbon Structure Research Articles

The Impact of Supersaturated Electrode on Heterogeneous Lithium Nucleation and Growth Dynamics

AbstractThe concept of a lithiophilic electrode proves inadequate in describing carbon‐based electrode materials due to their substantial mismatch in surface energy with lithium metal. However, their notable capacity for lithium chemisorption can increase active lithium concentration required for nucleation and growth, thereby enhancing the electrochemical performance of lithium metal anodes (LMAs). In this study, we elucidate the effects of the supersaturated electrode which has high active lithium capacity around equilibrium lithium potential on LMAs through an in‐depth electrochemical comparison using two distinct carbon electrode platforms with differing carbon structures but similar two‐dimensional morphologies. In the supersaturated electrode, both the dynamics and thermodynamic states involved in lithium nucleation and growth mechanisms are significantly improved, particularly under continuous current supply conditions. Furthermore, the chemical structures of the solid‐electrolyte‐interface layers (SEIs) are greatly influenced by the elevated surface lithium concentration environment, resulting in the formation of more conductive lithium‐rich SEI layers. The improved dynamics and thermodynamics of surface lithium, coupled with the formation of enhanced SEI layers, contribute to higher power capabilities, enhanced Coulombic efficiencies, and improved cycling performances of LMAs. These results provide new insight into understanding the enhancements in heterogeneous lithium nucleation and growth kinetics on the supersaturated electrode.

Microstructure reconstruction via confined carbonization achieves highly available sodium ion diffusion channels in hard carbon

Hard carbon is considered as the main candidate negative electrode material for sodium-ion batteries (SIBs) due to its high stability and electrochemical performance. However, the complex carbon structure and composition of hard carbon are difficult to achieve precise control during the preparation process, which leads to difficulties in accurately determining the attribution of electrochemical behavior. Here, we propose a confined carbonization strategy to achieve microstructure reconstruction of hard carbon, characterized by the anchoring of polymers in the mesopores of porous carbon to generate ordered carbon structures at high temperatures. The stacking of ordered carbon on micropores in porous carbon achieves the transition from exposed pores to closed pores (nano cleithral pores). Through mechanism detection, it is found that the ordered carbon structure provides sub nanochannels for sodium ion migration, which contributes to high slope capacity. In addition, the nano cleithral pores are sites filled with sodium ions and provide high plateau capacity. Benefiting from theses available sodium ion transport channels, carbon materials have achieved a transition from surface-controlled process to diffusion-controlled process in the sodium storage process via confined carbonization. The as-prepared carbon delivers a superior capacity of 356.2 mAh g–1 (215.6 mAh g–1 for plateau capacity) at 20 mA g–1 with excellent rate and cycling performance. This work reveals the correlation between structure and electrochemical performance for carbon electrode, providing profound guidance for the precise preparation of high-performance carbon materials.

Sulfur doped hollow cobalt–nitrogen–carbon oxidase-mimicking nanozyme enable sensitive chemiluminescence sensing serum total antioxidant capacity

Heteroatom doping is one of most important methodology for heightening catalytic activity of a nanozyme through modulating electronic configuration and coordinated environment of metal atoms. Here, a nitrogen/sulfur co-doped cobalt-decorated hollow carbon structure (CoS/NC) was fabricated through a simple and manageable template-assisted synthetic strategy, following high-temperature carbonization treatment. Remarkably, the CoS/NC has superior oxidase-mimicking activity than its counterparts and displays excellent catalytic action on the chemiluminescence (CL) reaction between luminol and dissolved oxygen (O2). The CoS/NC nanozyme-based CL system is highly sensitive to physiologically relevant antioxidants of both species including single electron transfer and hydrogen atom transfer. The detection limits can be reached as low as 3 nmol·L−1 ascorbic acid, 30 nmol·L−1 uric acid, 16 nmol·L−1 glutathione, and 28 nmol·L−1 cysteine. The total antioxidant capacity (TAC) of human serums has been determined in order to assess the feasibility of the CL system. The results of serum TAC, with ascorbic acid as an equivalent model, show a good consistency with those obtained by the standard CUPRAC method. This work not only benefits the rational design of a high catalytic functionality nanozyme, but also constructs a robust TAC detection platform for monitoring oxidative stress-related diseases.

Impact of Carbonization Temperature on the Structure and Li Deposition Behavior of 3D Dual Metal Carbon Fibers

Li deposition within lithiophilic–lithiophobic metal carbon fibers is influenced by several structural factors, including electrical conductivity, surface‐bound functional groups, particle size and distribution of the lithiophilic–lithiophobic components, which are significantly affected by the carbonization temperature. To gain a deeper understanding of how these different parameters affect the Li deposition behavior, a detailed analysis of Ag and Cu containing carbon fibers at carbonization temperatures from 500 to 1000 °C is performed. At lower carbonization temperatures, the fibers exhibit an unordered carbon structure with a high concentration of heteroatoms and a lithiophilic–lithiophobic gradient. However, the high electrical resistance at these temperatures impedes Li‐ion interaction with the fibers, leading to the formation of mossy and dead Li. In contrast, higher carbonization temperatures result in the removal of heteroatoms and a more ordered carbon structure. The agglomeration of Cu and Ag particles at these temperatures disrupts the lithiophilic–lithiophobic gradient, causing concentrated Li deposition on top of the fibers. A threshold temperature of 700 °C has been identified for achieving homogeneous Li deposition. At this temperature, the lithiophilic–lithiophobic gradient still exists, and the more ordered carbon structure enhances Li‐ion interaction with the fibers, resulting in stable Li deposition for over 1100 h.

Characteristics of organic carbon in tobacco-growing soils with different pH

This paper deal with the analysis of the relationship between acidity and alkalinity with organic carbon structure and humus components of tobacco-growing soils in Tengchong city. Under the same level of organic matter and nutrient content, soils with different pH values in Tengchong city were selected for the investigation. Results showed that the HA/FA values of the soil with low organic matter content gradually decreased with increasing pH, indicating a higher content of active carbon components and a lower content of stable carbon components in the soils. In soils with high organic matter content, pH value showed a highly significant negative correlation with HA/FA and PQ values. With increasing acidity, HA/FA became higher, and humus components with high stability increased. At the same level of organic matter content, the infrared A2920/A1630 ratio gradually increased with increasing pH. It indicates that at a certain pH range and the same level of organic matter content, the stable humus component increases, and the soil pH value decreases. Bangladesh J. Bot. 53(3): 745-755, 2024 (September) Special

Controlled chemical transformation of lignin by nitric acid treatment and carbonization

This study focuses on understanding the chemical reactions and results of Kraft lignin transformation through nitric acid treatment and subsequent carbonization. With its rich carbon content, lignin stands out as a promising candidate for the manufacturing of high-value carbon materials. The lignin underwent effective nitration, depolymerization, and oxidation under ambient conditions and at 40 °C, while a slight increase in reaction temperature significantly reduced the reaction time. The molecular weight Mw was effectively reduced from 4371 g/mol to 767 g/mol. The acid-treated lignin samples with incorporated nitro groups were further carbonized to create nitrogen-doped carbon structures. The resulting materials show stable nitrogen content (about at 5 wt%) even after carbonization due to the transformation of nitro groups into thermally stable pyridinic moieties, thereby exhibiting enhanced electrocatalytic properties compared to nitrogen-free carbon materials derived from Kraft lignin. The nitric acid-assisted treatment of lignin obviates the need for catalysts, and additional extraction or purification steps for preparing bio-derived carbon precursors, rendering it facile, fast, and cost-efficient.

Fast, Regioselective Aminolysis of Tetrasubstituted Cyclic Carbonates and Application to Recyclable Thermoplastics and Thermosets.

Herein, the long-standing challenge of the ring-opening aminolysis of CO2-derived tetrasubstituted cyclic carbonates at room temperature (r.T) is overcome under catalyst-free conditions. Molecular design of the cyclic carbonate by substitution of an alkyl group by a thioether unlocks quantitative conversion at r.T and ensures total regioselectivity toward highly substituted oxazolidone scaffolds. An in-depth rationalization of the high reactivity of these cyclic carbonate structures and of the aminolysis reaction mechanism is provided by a computational study supporting experimental observations. The high efficiency of the reaction is then translated to the deconstruction of high-performance thermoplastics containing tetrasubstituted cyclic carbonate linkages to deliver building blocks that are reused for designing recyclable thermosets bearing dynamic N,S-acetal linkages.

Sugarcane straw biochar: effects of pyrolysis temperature on barite dissolution and Ba availability under flooded conditions

AbstractReductive dissolution of barium (Ba) sulfate in wetland soils may increase Ba bioavailability in the environment, yet no information is available regarding Ba remediation using biochar. This study investigated the effectiveness of sugarcane (Saccharum officinarum) straw biochar pyrolyzed at 350 °C (BC350), 550 °C (BC550), and 750 °C (BC750) in inhibiting barite dissolution and, consequently, Ba availability in a soil artificially spiked with barite and flooded for 365 days. Increasing pyrolysis temperature alters the carbon structure, and increases dehydration and depolymerization, resulting in more stable biochar that releases less DOC (8.6-fold decrease from BC350 to BC750). Additionally, high-temperature biochar (BC750) had 1.7 times higher carbon (C) content, 2.4 times higher ash content, and a 13.1 times greater specific surface area (SSA) than low-temperature biochar (BC350). Amending soil with BC750 increased pH but did not promote reducing conditions, and thus did not promote barite dissolution. Conversely, greater DOC in low-temperature biochar, particularly BC350, favored reducing conditions and increased barite dissolution by 23%, with BC550 also showing an 18% increase. This enhancement led to a greater pool of Ba sorbed into more labile exchangeable sites. In summary, pyrolysis temperature affects biochar attributes, which in turn influences the soil geochemical environment and Ba speciation. Low-temperature biochar (BC350) shows potential as an amendment to increase the bioavailable Ba pool in assisted remediation programs, such as biochar-assisted phytoremediation. Graphical Abstract

A new plastic global analysis approach for the fire design of steel and stainless steel structures

The new generation of structural codes for stainless steel allow carrying out global plastic analyses on certain types of stainless steel structures with plastic cross-sections at room temperature if the joints conforming the structure are classified as full-strength joints, a capability that has been long recognised for carbon steel structures. However, the requirements for the fire design of carbon and stainless steel structures in current and upcoming European design standards are still primarily based on the resistance of individual members, disregarding the redistribution of internal forces and strain hardening effects. Recent studies have proven that carbon and stainless steel frames with plastic cross-sections and full-strength joints are capable of redistributing internal forces at elevated temperatures, and failed describing global plastic collapse mechanisms under fire situation, suggesting that system effects are also relevant at elevated temperatures and could be taken into account for more efficient designs. On this basis, this paper develops an extensive numerical study focused on carbon and stainless steel frames under fire situation, and proposes a new methodology based on plastic global analysis to estimate the resistance of such structures under fire situation accounting for their redistribution capacity, improving the accuracy of the predicted fire time resistances significantly for the two materials.

Decoupling study of municipal solid waste gasification: Effect of pelletization on pyrolysis and gasification of pyrolytic char

To explore the influence of pelletization on the thermal conversion of municipal solid waste (MSW), pyrolysis characteristics and gasification reactivity of MSW pellet and powder were investigated in this study. Besides, the physicochemical properties of internal char and external char within the char pellet were separately characterized. Moreover, the relationship between the physicochemical properties of char pellet and its gasification reactivity was clarified. Results showed that the pyrolytic gas yields of MSW pellets were increased by 15.47 % and 11.55 % at 700 °C and 800 °C, respectively, compared to powder MSW. It was mainly attributed that the conversion of monocyclic aromatic hydrocarbons to polycyclic aromatic hydrocarbons was promoted by the longer residence time within the pellets. Meanwhile, the physicochemical properties of pyrolytic char pellets exhibited a significant heterogeneity. Specifically, the number of ordered aromatic rings of char pellet was reduced, while the order degree of carbon structure was enhanced, particularly the internal char. However, the difference magnitude between internal and external char was diminished with temperature. This was due to the higher temperature resulting in a larger surface specific area and pore volume of the char pellet, especially the internal char, thereby enhancing the pyrolysis process. Furthermore, an increase in pore volume within the char pellet improved gasification reactivity when the conversion rate > 0.4. These findings provide a reference for the pyrolysis and gasification process of MSW pellets.

Problems and solutions to protection of carbon-graphite electrodes

This paper presents literature review of the existing problems and solutions in protecting carbongraphite electrodes from the destructive environment of arc steel-making furnaces, magnesium and aluminum cells. The most significant publications on the corrosion resistance of cathodes and anodes in relation to physical, chemical, and electrochemical wear, to oxidizing environments, to active components of the introduction and destruction of the carbon structure are discussed. An analysis of various proposals and engineering solutions for reducing or eliminating the impact of aggressive environments on electrodes under specific operating conditions of metallurgical units is carried out. It was established that losses from lateral oxidation of the electrode surface of arc steel-making furnaces, when passing the temperature zone of 600–800°C, may reach 40–60% of the total consumption. Carbon-graphite products are subject to a significant destructive effect of the specific interaction of carbon with elements and compounds of the working environment, which can be introduced (intercalate) into the interlayer structure of carbon. The existing engineering and technological solutions mainly apply to the protection of the product surface; moreover, they perform their functions for a short time, rather than during the entire service life of the metallurgical unit. In this connection, it is proposed to focus on ensuring volumetric protection of electrodes from the effects of an aggressive environment. Intermediate results obtained in the field of synthesis of carbonbased composite materials adapted to the conditions of electrode production at existing enterprises are presented, along with the results of studies into the oxidizability of these composites. The existing and proposed engineering solutions for protecting the surface of carbon products have not received wide recognition or are not used in the metallurgical industry. Among the most probable reasons are the limited period of electrode surface protection, the complexity of reproduction, or the lack of profitability due to the high cost of protective components. In this regard, synthesis of C – TiC/TiB2 composite electrodes based on petroleum coke and graphite seems to be a promising research direction.

Optimized pyrolytic synthesis and physicochemical characterization of date palm seed biochar: unveiling a sustainable adsorbent for environmental remediation applications.

This study focuses on the optimization and comprehensive characterization of biochar synthesized from date palm seeds (DPS), a prevalent agricultural waste in arid regions. Using response surface methodology (RSM) with a central composite design (CCD), we optimized the pyrolysis process by investigating the effects of time (1-3 h) and temperature (600-900 °C) on critical properties such as specific surface area, pore volume, and yield. The optimized biochar, produced at 828 °C for 1.7 h, demonstrated a high specific surface area of 654.8 m2/g and well-developed microporosity. Characterization techniques, including XRD, FTIR, SEM-EDS, and BET analyses, revealed an amorphous carbon structure with graphitic domains, diverse surface functionalities, and a heterogeneous porous microstructure. The biochar's point of zero charge at pH 7.58 indicates its potential for selective adsorption of charged contaminants. The close agreement between RSM-predicted and experimental values for specific surface area (652.1 m2/g vs. 654.8 m2/g) and micropore volume (0.191 cm3/g vs. 0.190 cm3/g) validates the effectiveness of the model in optimizing biochar properties. This research highlights the potential of DPS-derived biochar as a sustainable adsorbent for environmental remediation, opening avenues for valorizing agricultural wastes and contributing to circular economy principles.

Accurate carbon structure for prediction of reaction pathway during bio-coal production using torrefaction

The structural parameters of carbon were accurately determined through correction by employing a linear correlation method. Further, the nuclear Overhauser effect (NOE) was reduced in solid 13C-nuclear magnetic resonance spectra using a solid cross-polarization/magic angle spinning (CP/MAS) probe and the total suppression of sidebands sequence (TOSS). The reaction pathway during torrefaction was inferred from analysis of the accurate bond behavior and product distribution. The results show that torrefaction has a significant influence on the structural evolution of biomass. After correction, the relative deviations in the H/C ratio and aromaticity of the carbon structure decreased below 20 %. During torrefaction, the aliphatic carbon bonds were cleaved and aromatic carbon bonds were formed by dehydration, deoxygenation, oligomerization, aromatization, and Diels-Alder reaction. Torrefaction of biomass is divided into three stages. The first stage occurs below 220 °C, with disruption of the hydrogen bonds, a decrease in the number of Cal-O bonds, and the release of some CO2, CO, and furaldehyde. The second stage proceeds in the 220–260 °C range, where β-O-α bonds and glycoside bonds are broken, with the generation of ketones, furan, phenols, CO, and CO2. In the third stage between 260 and 300 °C, Cal-O and Cal-Cal bonds are broken. Bio-coal is composed of monomers of C20H14O3 with two aromatic rings linked by one aromatic ring. This significant, fundamental study enables accurate calculation and simulations for optimizing the industrial utilization of biomass.

Engineered biochar for advanced oxidation process towards tetracycline degradation: Role of iron and graphitic structure

The excessive accumulation of tetracycline (TC) presents significant challenges to both human health and the ecological environment. This study explores the impact of Fe-loaded sawdust graphitic carbon (engineered biochar) on TC degradation in water, utilizing an advanced oxidation process facilitated by H2O2 activation. The investigation encompasses an examination of the structural characteristics of Fe-loaded sawdust graphitic carbon and an in-depth analysis of its catalytic degradation mechanism concerning TC. Density functional theory (DFT) was utilized to construct an adsorptive degradation system for TC in water, thereby scrutinizing the optimal treatment process for TC. The findings highlight that Fe-loaded biochar exhibits not only a substantial pore structure but also inherent defects and a graphitic structure. The porous configuration enhances the TC adsorption capacity of the biochar system, while the graphitic structure bolsters the stability of the carbon framework, ensuring efficient charge transfer via the carbon defects. The activation effect of Fe(III) on H2O2 into ·O2- is dependent on its specific location within the carbon structure. In the presence of 5 mmol H2O2, Fe-loaded biochar achieves a nearly 100 % degradation rate of TC, with its degradation proficiency minimally influenced by varying pH conditions.

Preparation of highly graphitized porous carbon and its ethane/ethylene separation performance

The efficient separation of ethane (C2H6) and ethylene (C2H4) is crucial for the preparation of polymer-grade C2H4, necessitating the development of highly selective and stable C2H6/C2H4 adsorbents. Highly graphitized porous carbon, denoted GC-800, was synthesized by polymerization at room temperature followed by carbonization at 800 °C using phenolic resin as the precursor and FeCl3 as the iron source. Vienna Ab-initio Simulation Package (VASP) calculations confirmed a higher binding energy between C2H6 molecules and graphitized porous carbon surfaces, so that a high degree of graphitization increased the adsorption capacity of porous carbon for C2H6. However, catalytic graphitization using Fe at high temperatures disrupted the microporous structure of the carbon, thereby reducing its ability to separate C2H6/C2H4. By controlling the carbonization temperature, the degree of graphitization and pore structure of the porous carbon could be changed. Raman spectra and XPS spectra showed that the GC-800 had a high degree of graphitization, with a sp2 C content as high as 73%. Low-temperature N2 physical adsorption measurements estimated the specific surface area of GC-800 to be as high as 574 m2·g−1. At 298 K and 1 bar, it had an equilibrium adsorption capacity of 2.16 mmol·g−1 for C2H6, with the C2H6/C2H4 (1:1 and 1:9, v/v) ideal adsorbed solution theory selectivity respectively reaching 2.4 and 3.8, significantly higher than the values of most reported high-performance C2H6 selective adsorbents. Dynamic breakthrough experiments showed that GC-800 could produce high-purity C2H4 in a single step from a mixture of C2H6 and C2H4. Dynamic cycling tests confirmed its good cyclic stability, and that it could efficiently separate C2H6/C2H4 even under humid conditions.

Influence of Phosphoric Acid Activation on Physiochemical Characteristics of Activated Carbons and Their Performance as Supercapacitor

ABSTRACTWe investigate the influence of phosphoric acid (H3PO4) activation on physiochemical characteristics of activated carbons (ACs) as a function of number of activation steps such as two‐step and three‐step and impregnation ratio (IR). Scanning electron microscopy observations identified that different morphologies in the forms of graphene sheet‐like, nano‐granular, and flake‐like carbon structure in the cases of ACs. FTIR spectroscopy confirmed that successful incorporation of phosphorous group in the ACs by H3PO4 activation. X‐ray diffraction (XRD) profile exposed that irrespective of the activation method and IR, all AC samples showed narrow and sharp XRD crystalline peak along with the amorphous signals. Raman scattering analysis suggested that three‐step activation create more defective structure as compared to two‐step activation route. Nitrogen adsorption–desorption isotherm measurements indicated that upon fabricating ACs via three‐step and two‐step activation approach, around 6.5 times and 3‐fold enhancement in the value of surface area of ACs as compared to that of carbon before activation. In addition, higher the IR value, lower the textural properties of ACs. This study demonstrated that three‐step activation methodology is capable of generating highly porous AC when compared to two‐step activation route. Cyclic voltammetry analysis showed that for the electrode developed from AC that fabricated via three‐step activation, capacitance retention of 50% is achieved upon tuning the scan rate by 10 times. The same electrode exhibited the capacitance retention of 45% upon increasing the current density by 10 times. We have also compared the electrochemical performance of symmetric and asymmetric supercapacitors. Electrochemical capacitance retention of symmetric and asymmetric supercapacitors is determined to be 100% and 92% respectively after 1000 cycles at the current density of 1 A g−1. Based on the Ragone plot study, it is observed that the maximum energy density of 5 W h kg−1 and the maximum power density of 943 W kg−1 are attained for the case of symmetric supercapacitors. Asymmetric supercapacitor displayed improved energy density of 7.15 W h kg−1 and modest power density of 432 W kg−1.

The potassium storage performance of carbon nanosheets derived from heavy oils

As by-products of petroleum refining, heavy oils are characterized by a high carbon content, low cost and great variability, making them competitive precursors for the anodes of potassium ion batteries (PIBs). However, the relationship between heavy oil composition and potassium storage performance remains unclear. Using heavy oils containing distinct chemical groups as the carbon source, namely fluid catalytic cracking slurry (FCCS), petroleum asphalt (PA) and deoiled asphalt (DOA), three carbon nanosheets (CNS) were prepared through a molten salt method, and used as the anodes for PIBs. The composition of the heavy oil determines the lamellar thicknesses, sp3-C/sp2-C ratio and defect concentration, thereby affecting the potassium storage performance. The high content of aromatic hydrocarbons and moderate amount of heavy component moieties in FCCS produce carbon nanosheets (CNS-FCCS) that have a smaller layer thickness, larger interlayer spacing (0.372 nm), and increased number of folds than in CNS derived from the other three precursors. These features give it faster charge/ion transfer, more potassium storage sites and better reaction kinetics. CNS-FCCS has a remarkable K+ storage capacity (248.7 mAh g−1 after 100 cycles at 0.1 A g−1), long cycle lifespan (190.8 mAh g−1 after 800 cycles at 1.0 A g−1) and excellent rate capability, ranking it among the best materials for this application. This work sheds light on the influence of heavy oil composition on carbon structure and electrochemical performance, and provides guidance for the design and development of advanced heavy oil-derived carbon electrodes for PIBs.

Contact fatigue property of diamond-like carbon films with different structure in cyclic impact conditions

Repeated contact with high loads can cause damage to the surface of the DLC films and thus affect their fatigue strength. This study systematically investigates the contact fatigue damage of the DLC films with different carbon structures (a-C, a-C:H, and ta-C) by macro-scale cyclic impact tests with alternating loads. The results reveal that the a-C film possesses significantly superior contact fatigue property compared to the a-C:H and ta-C films under high load. The graphitization transformation of the a-C and a-C:H films lead to a decrease in hardness and elastic modulus. The work-hardening of the ta-C films results in an increase in hardness and elastic modulus. The findings indicate that under cyclic load impact conditions, films need a combination of load support and fatigue resistance to achieve optimum lifetime, and solely increasing film hardness could be accompanied by brittle fracture and higher wear.

Burnt Cervidae bones and sedimentary environments at Luotuodun, Jiangsu Province, China: New insights for Neolithic human behavior

The Luotuodun archaeological site is located in Yixing City, Jiangsu Province, in the transition zone from the Yili Mountains to the coastal plain. It is of Neolithic Age and dates from approximately 7000 to 5000 years ago. A large number of animal skeleton fossils have been unearthed at the site, many of which, especially those belonging to species of Cervidae (possibly Sika, Cervis nippon), are characterized by the presence of black residue on the surface. There are three types of residue, one is black film-like coating, which is suggestive of exposure to fire, one is also black, but crystalline in nature, while the other is grey-white, particulate deposit. With the aim of exploring the nature of these residues and their possible origins, we applied a number of analytical techniques, including Raman Spectroscopy (RS), Fourier Transform Infrared Spectroscopy (FTIR), Energy dispersive spectroscopy (EDS) and Electron Microscopy (EM) on six bone fossils belonging to different parts of Cervidae skeleton unearthed from Luotuodun to evaluate the possible influence of fire and/or depositional processes in their formation. The black film-like coating, widespread on the surface of these bones, is highly reflective and appears white under the Raman microscope. The RS peak indicates that the film-like substance is rich in carbonaceous (graphitic carbon) components, suggesting that the bones have been exposed to combustion. FTIR measurements on these bones show that the structure of hydroxyapatite carbonate (Ca10(PO4)6−x(CO3)x(OH)2) has changed, consistent with their exposure to very high temperatures (500–600 °C), and implying that they were burnt, either for cooking or ritual behavior by ancient humans. In the case of the crystallized black particles, these are primarily confined to localities on the surface of bone fractures. EDS results, as confirmed by the RS analysis, show that the black crystals are comprised of an iron-rich, phosphatic mineral, compatible with vivianite (Fe3(PO4)2·(H2O)8). The substantial vivianite content is consistent with the fossil bones being submerged and deposited in waterlogged soils. The results of EDS show that the composition of the grey-white particle is hydroxyapatite carbonate (Ca10(PO4)6−x(CO3)x(OH)2). Non-destructive geochemical analysis of the surface residues of these Luotuodan bones provides valuable evidence for reconstructing the taphonomy of the Cervidae bones, and reveals that they were utilized by ancient humans during the Luotuodun culture period in SE China.

Surface-modified composites of metal–organic framework and wood-derived carbon for high-performance supercapacitors

The renewable nature, high carbon content, and unique hierarchical structure of wood-derived carbon make it an optimal self-supporting electrode for energy storage. However, the limitations in specific surface area and electrical conductivity defects pose challenges to achieving satisfactory charge storage in wood-derived carbon electrodes. Therefore, exploring diverse and effective surface strategies is crucial for enhancing the electrochemical energy storage performance. Herein, a decoration technique for enhancing aesthetic appeal involves applying a metal–organic framework (Ni/Co-MOF) containing nickel and cobalt onto the inner walls of wood tracheids. The sequential modification steps include carbonization, oxidation activation, and acid-etching. The Ni/NiO/CoO-CW-4 electrode, made by acid-etching carbonized wood (CW) doped with nickel, nickel oxide, and cobalt oxide for 4 h, has excellent surface area and pore size distribution, high graphitization degree, and exceptional conductivity. Furthermore, surface modification optimizes the surface chemistry and phase composition, resulting in a 0.8 mm thick Ni/NiO/CoO-CW-4 electrode with an exceptionally high areal capacitance of 16.76 F cm−2 at 5 mA cm−2. Meanwhile, the fabricated solid-state supercapacitor achieves an impressive energy density of 0.67 mWh cm−2 (8.38 mWh cm−3) at 2.5 mW cm−2 (31.25 mW cm−3), surpassing representative modified wood-based carbon electrodes by approximately 2–7 times. Additionally, the supercapacitor demonstrates exceptional stability, maintaining 96.21 % of capacitance even over 10,000 cycles. The parameters presented here demonstrate a significant improvement compared to those typically observed in most modified wood-derived carbon-based supercapacitors, effectively addressing common issues of low energy density and suboptimal cycling performance with wood carbon composites.