Carbon Precursor Research Articles

Utilizing Carbonaceous Materials Derived from [BMIM][TCM] Ionic Liquid Precursor: Dual Role as Catalysts for Oxygen Reduction Reaction and Adsorbents for Aromatics and CO2.

This work presents the synthesis of N-doped nanoporous carbon materials using the Ionic Liquid (IL) 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM] as a fluidic carbon precursor, employing two carbonization pathways: templated precursor and pyrolysis/activation. Operando monitoring of mass loss during pyrolytic and activation treatments provides insights into chemical processes, including IL decomposition, polycondensation reactions and pore formation. Comparatively low mass reduction rates were observed at all stages. Heat treatments indicated stable pore size and increasing volume/surface area over time. The resulting N-doped carbon structures were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) and adsorbents for gases and organic vapors. Materials from the templated precursor pathway exhibited high electrocatalytic performance in ORR, analyzed using Rotating Ring-Disk electrode (RRDE). Enhanced adsorption of m-xylene was attributed to wide micropores, while satisfactory CO2 adsorption efficiency was linked to specific morphological features and a relatively high content of N-sites within the C-networks. This research contributes valuable insights into the synthesis and applications of N-doped nanoporous carbon materials, highlighting their potential in electrocatalysis and adsorption processes.

From longan peel waste to energy storage: Porous activated carbon as a cathode matrix for advanced Li/Na-selenium batteries

This paper explores the potential of Longan peel waste (LPw) as a sustainable and cost-effective matrix for selenium-based cathodes in Li-Se and Na-Se batteries. Following activation, we created LP2—a designation for the carbon precursor derived from LPw, activated at a 1:2 ratio of carbonized LPw to KOH. This nomenclature, where ‘LP' stands for ‘Longan peel' and ‘2′ reflects the optimization of this ratio, led to a hierarchical porous structure with an average pore size of 3.0307 ​nm and a significant BET surface area of 111.9386 ​m2 ​g-1. Selenium was incorporated into the LP2 matrix using a simple melt diffusion technique, yielding the composite Se@LP2. In Li-Se batteries, Se@LP2 exhibited an initial discharge capacity of 1033.75 mAh g⁻1 ​at 0.1C. At a 1C rate, the composite demonstrated a capacity retention of 301.14 mAh g⁻1 after 550 cycles and 380.91 mAh g⁻1 after 100 cycles. Moreover, for Na-Se batteries, the composite showcased a capacity retention of 347.18 mAh g⁻1 after 100 cycles at 0.1C. These findings underscore LP2's potential as a viable and efficient matrix for selenium-based cathodes, revealing promising prospects for the advancement of highly efficient Li-Se and Na-Se batteries.

Catalytic potential of green ordered mesoporous carbons, obtained from biomass-derived xylose, glucose, and lignin

Green high-surface area Ordered Mesoporous Carbons (OMCs) (576–948 m2/g) were successfully synthesized by the hard template method using xylose, glucose and lignin solutions obtained from almond shells, a local biomass waste, as carbon precursors, and SBA-15 as a template. The catalytic potential of OMCs, as catalytic supports or as catalysts, has been preliminarily tested for different reactions of interest. A dried sulfonic-acid treated OMC, obtained from xylose extract, led to full conversion and 92% selectivity to di- and tri-ethers of glycerol for the glycerol etherification with isobutene at 80 °C. A sulfonic-acid treated OMC, obtained from glucose, presented a higher turnover frequency (TOF) value and slightly lower selectivity to levulinic acid than commercial Amberlyst-15 for the conversion of 5-hydroxymethylfurfural at 180 °C. The use of an OMC obtained from lignin as catalytic support of a nickel catalyst combined with H-Beta led to 78% of selectivity to cyclohexane at total conversion for the hydrodeoxygenation of guaiacol at 180 °C.

Comparison of Pd Nanoparticle-Decorated Softwood and Hardwood Activated Carbon in Catalytic Reduction of High-Concentrated Industrial 4-Nitrophenol

Carbon-based catalyst from natural wood recently shows a great potential in environmental remediation due to its naturally hierarchical and anisotropic porous structure. However, few studies have focused on the difference in structure-property-function between the two categories of hardwood and softwood. Herein, Pd nanoparticles decorated softwood (Pd/SAC) and hardwood activated carbon (Pd/HAC) were fabricated for catalytic reduction of high-concentrated 4-nitrophenol (4-NP, 2.0 g L−1). The results show that the developed Pd/HAC has larger specific surface area (474 m2 g−1), more abundant pits and nanopores than Pd/SAC (412 m2 g−1), offering Pd/HAC with abundant interpenetrating channels for efficient mass transfer. As a result, Pd/HAC demonstrates outstanding performance in catalytic reduction of 4-NP, with the turnover frequency value up to 1.25 mol4-NP mol−1 min−1, much higher than Pd/SAC (0.92 mol4-NP mol−1 min−1), even at lower Pd nanoparticles loading (0.551 % vs. 0.573 %). The mesopores/micropores ratio of wood-based activated carbon is considered to be an important parameter affecting the mass transfer process. Pd/HAC also demonstrates superior catalytic stability and reusability, with the shedding degree of decorated Pd nanoparticles much lower than Pd/SAC when subjected to 9 cycles. Hardwood is demonstrated to be a promising activated carbon precursor, and exhibits unique hierarchical porous structure that can highly promotes the catalytic performance in industrial wastewater treatment.

Synergistic effect of green trace K2CO3 and CO2 activation of zhundong coal for high-performance supercapacitors

Porous activated carbons prepared by green trace K2CO3-assisted CO2, H2O, and CO2/H2O activated high-alkali Zhundong coal are being employed as supercapacitor electrode materials. Effects of trace K2CO3 (2 wt% of carbon precursor) and gas composition on physicochemical structure, the morphology and supercapacitor properties of the active carbon are investigated in detail. The results are showing that activated carbon from trace K2CO3-assisted CO2 activation exhibited excellent performance, indicating that CO2 and K2CO3 have synergistic effect in the activation process. It is mainly due to the higher O content in CO2/N2 atmosphere and promotion by K of O transfer from CO2 to the carbon matrix, which produces more active sites. Trace K2CO3-assisted CO2 activated carbon forms a forked hierarchical pore structure, more oxygen-containing functional groups, increases surface free energy of porous carbon, more potassium-containing group structures, and excellent graphitization of amorphous carbon compared with the other carbons. Its corresponding electrode and symmetrical supercapacitor achieve specific capacitance of 277.7 and 114.5 F g−1, respectively. The energy density is 10.54 Wh kg−1 at 209.98 W kg−1 and the material retained 95.89% after 10 000 cycles. A novel method of green trace K2CO3-assisted CO2 activation of high-alkali Zhundong coal is proposed for high-performance supercapacitors.

Nitrogen-Containing Carbon Tubes Fabricated by Light Irradiation.

Cotton-core/polypyrrole (PPy)-sheath fibers (cotton/PPy fibers) were synthesized by aqueous chemical oxidative seeded polymerization and were utilized as precursors for nitrogen-containing carbon (NCC) tubes. Irradiation of the cotton/PPy fibers with a near-infrared (NIR) laser heated them to approximately 300 °C due to light-to-heat photothermal conversion by the PPy, and the cotton core was thermally decomposed and vaporized. Scanning electron microscopy studies revealed the formation of tubes with monodispersed diameters, and elemental microanalysis, Fourier transform infrared spectroscopy, and Raman spectroscopy confirmed that the PPy sheath was converted into NCC. Furthermore, sunlight also worked as the light source in fabricating the NCC tubes. The thicknesses of the tubes were controlled between 410 nm and 2.30 μm by tuning the PPy sheath thickness. The method developed in this study can be extended to other polymeric fibers, including acrylic and wool fibers. The shapes of the cross sections and surface nanomorphologies of the NCC tubes can be reflected in those of the polymer/PPy fibers.

Pitch-based 3D tremella-like porous carbon with cavitary structures: Applications in symmetric capacitors and zinc ion capacitors

The application of porous carbon in electrochemical energy storage devices (e.g., symmetrical capacitors, SCs, zinc ion capacitors, ZICs) is of great value, while pitch is one of the excellent precursors of porous carbon. Herein, the pitch-based 3D tremella-like porous carbons with heteroatoms (N and O) and cavitary structures have been synthesized via one-step oxidation activation. This strategy can introduce oxygen atoms to effectively inhibit the conjugation effect of the pitch and improve the convenience of preparation. The melting and crystallizing effect of NaCl can help the creation of cavitary structures and hierarchical pores. Gases released from the pyrolysis of pitches and decomposition of K2C2O4 contribute to the distortion of the carbon structure, resulting in the tremella-like morphology. The best sample, PC-825, has a specific capacitance of 338.5 F g−1 in a three-electrode system and an energy density of 12.2 Wh kg−1 in SCs. More importantly, PC-825 as cathodes in ZICs has a specific capacitance of up to 193.1 mAh g−1 and an energy density of up to 154.5 Wh kg−1, realizing an outstanding zinc storage capacity. This work realizes the conversion of cheap pitch to high-value-added electrochemical materials.

Synthesis of green fluorescent, energy efficient nitrogen doped carbon quantum dots

The study of a simple and facile microwave heating technique is introduced for the synthesis of nitrogen-doped carbon quantum dots (N-CQDs) with the most abundant and cheap chemicals- Citric acid (carbon source & precursor) and Urea (nitrogen source & reducing agent). TEM and DLS results indicated that such prepared N-CQDs have an average particle size of ∼0.8 nm and high Quantum Yields of ∼24.69%. UV-Vis and PL Spectroscopic results indicated that these N-CQDs have bright green color fluorescence under the excitation of 405 nm wavelength and are highly dispersible in water and provide a stable optically transparent yellowish solution in ambient light. FTIR results confirmed the Nitrogen Doping over these CQDs as it consists of N-H vibrational structural bonds. XRD results display a diffraction peak at 27°, which corresponds to the (002) plane of a graphitic structure revealing an amorphous carbon phase.TEM results also demonstrated that these materials have good spherical morphology. Their high fluorescence/ photoluminescence, small size, chemical stability, high quantum yields, broad excitation range, and porous nature make them better candidates in the field of optoelectronics such as Solar cells and Light emitting diodes (LEDs), biosensing/imaging, and energy storage such as Li-Ion Batteries and supercapacitors.

Lubricity performance of hydrogen-free CVD growth of graphene on copper particles as an additive in paraffin base oil

This study aims to examine the impact of carbon precursor materials, which are oil palm fiber (OPF) and waste polystyrene (PS), on friction and wear properties of paraffin base oil added with graphene-coated copper (Cu) additive. The graphene was synthesized on Cu particles via hydrogen-free chemical vapor deposition method. The graphene was characterized using Raman spectroscopy and transmission electron microscopy. The lubricity properties of 0.6 wt.% of synthesized graphene-coated Cu additive in paraffin base oil was analyzed based on its tribological behavior using a four-ball tribometer. From the quantitative and qualitative characterization analysis, graphene-coated Cu additive synthesized using 50 wt.% OPF carbon precursors has a good-quality graphene with minimal defects and a well-ordered lattice structure. From the tribological analysis, the paraffin base oil added with graphene-coated Cu additive synthesized using 50 wt.% OPF carbon precursor has the lowest coefficient of friction of 0.07 and wear rate of 1.6 × 10−5 mm3/min. Hence, it can be suggested that incorporating graphene-coated Cu particles, synthesized from a 50 wt.% OPF carbon precursor, into base oil shows great potential as an environmentally friendly additive, particularly in terms of enhancing lubrication performance.

Corrosion and heat-resistant SiCN/C as lightweight fibers for microwave absorption and electromagnetic field shielding in Ku-band

SiCN fibers are usually combined with metals to increase the magnetic loss in electromagnetic field (EMF) shielding, but this results in high weight density, easy corrosion, difficult treatment, and high cost of the material. This study proposes the manufacturing of corrosion and heat-resistant ceramic lightweight fibers containing in-situ synthesized carbon nanostructures (SiCN/C) with excellent EMF shielding in Ku-band (12.4–18 GHz). The samples showed differential trends of EMF shielding effectiveness in terms of reflectance, transmittance, and absorption behavior. Compared to SiCN fibers, the EMF absorption was two times greater when carbon was added to the SiCN matrix. A minimum reflection coefficient (S11) of −12 dB was observed for SiCN/C fibers, meaning a high shielding efficiency with >90 % of the EMF energy shielded. On the other hand, SiCN fibers showed a minimum S11 of −7 dB, resulting in a protection of 80 % against EMF energy. Computational simulations clarified the better features of SiCN/C in electromagnetic shielding compared to SiCN, which was ascribed to enhanced conduction loss derived from conductive free carbon, and dipole and interfacial polarization loss generated by defects. The fibers were resistant to acidic and basic environments and oxidation of up to 600 °C. Moreover, the addition of carbon precursor represented a weight decrease of 17 % for SiCN/C compared to SiCN fibers. This research will afford an alternative solution for the manufacturing of SiCN/C fibers with EMF absorption properties that can be used as lightweight materials in harsh environments.

Effect of Carbonization Temperature on the Structure of Pitch Carbon and Its Low-temperature Lithium Storage Properties

Introduction:: Lithium-ion batteries were one of the most promising battery systems for electric vehicles. Currently, lithium-ion batteries are required to have higher energy density and cycle stability. The traditional graphite negative electrode cannot meet the requirements. Pitch has many advantages such as wide source, low cost, high carbon residue rate and easy graphitization, as a carbon precursor has been widely used in lithium-ion battery anode and anode materials. Method:: In this paper, pitch carbon was prepared by carbonization at different temperatures and studied. Result:: The results showed that with the increase of carbonization temperature, the interlayer spacing decreased gradually, the degree of amorphousness decreases gradually, the specific surface area and pore volume also decrease gradually, the initial coulombic efficiency and capacity retention increased, and the discharge-specific capacity decreased. Galvanostatic Intermittent Titration Technique (GITT) tests show that there are two main mechanisms of lithium ions intercalation in the material, surface adsorption and interlayer intercalation. Conclusion:: The difficulty of diffusion of lithium ions between pitch carbon layers at low temperatures is the main reason for the decrease of its capacity at low temperature. The carbon material obtained by carbonization of pitch at 800℃ has the best low temperature performance, with discharge specific capacities of 335, 272, 232 and 187mAh/g at 25, 0, -20 and -40℃, of which 55.8% of the discharge specific capacity at room temperature can be retained at -40℃. The amorphous carbon material has certain low temperature charge-discharge performance.

Study on the lignin-derived sp2–sp3 hybrid hard carbon materials and the feasibility for industrial production

Hard carbon has been widely used in anode of lithium/sodium ion battery, electrode of supercapacitor, and carbon molecular sieve for CO2 capture and hydrogen storage. In this study the lignin derived hard carbon products are investigated, and the conclusions are abstracted as follows. (1) The lignin derived hard carbon products consist of microcrystal units of sp2 graphene fragments, jointed by sp3 carbon atoms and forming sp2–sp3 hybrid hard carbon family. (2) From the lignin precursors to the sp2–sp3 hybrid hard carbon products, most carbon atoms retain their original electron configurations (sp2 or sp3) and keep their composition in lignin. (3) The architectures of lignin-derived hard carbon materials are closely dependent on the forms of their lignin precursors, and could be preformed by different pretreatment techniques. (4) The carbonization of lignin precursors follows the mechanism “carbonization in situ and recombination nearby”. (5) Due to the high carbon ratio and abundant active functional groups in lignin, new activation techniques could be developed for control of pore size and pore volume. In general lignin is an excellent raw material for sp2–sp3 hybrid hard carbon products, a green and sustainable alternative resource for phenolic resin, and industrial production for lignin derived hard carbon products would be feasible.

Porous and graphitic carbon nanosheets with controllable structure for zinc-ion hybrid capacitor

The imbalances of storage capacity and reaction kinetics between carbonaceous cathodes and zinc (Zn) anodes restrict the widespread application of Zn-ion hybrid capacitor (ZIHC). Structure optimization is a promising strategy for carbon materials to achieve sufficient Zn2+ storage sites and satisfied ion–electron kinetics. Herein, porous graphitic carbon nanosheets (PGCN) were simply synthesized using a K3[Fe(C2O4)3]- and urea-assisted foaming strategy with polyvinylpyrrolidone as carbon precursor, followed by activation and graphitization. Sufficient pores with well-matched pore sizes (0.80–1.94 nm) distributed across the carbon nanosheets can effectively shorten mass-transfer distance, promoting accessibility to active sites. A partially graphitic carbon structure with high graphitization degree can accelerate electron transfer. Furthermore, high nitrogen doping (7.2 at.%) provides additional Zn2+ storage sites to increase storage capacity. Consequently, a PGCN-based ZIHC has an exceptional specific capacity of 181 mAh g−1 at 0.5 A g−1, superb energy density of 145 Wh kg−1, and excellent cycling ability without capacity decay over 10,000 cycles. In addition, the flexible solid-state device assembled with PGCN exhibits excellent electrochemical performances even when bent at various angles. This study proposes a straightforward and economical strategy to construct porous graphitic carbon nanosheets with enhanced storage capacity and fast reaction kinetics for the high performance of ZIHC.

Coal Tar Pitch Derived sp2 Configuration‐Dominated Vacancy‐Rich Carbon with Expand Interlayer Spacing for Low‐Voltage, Durable, and Fast Potassium Storage

AbstractThe low‐voltage charging capacity and rate performance are two crucial but mutually restricted properties of K‐ion batteries. Herein, a sulfonamide and amide linkages‐triggered N doping high‐temperature removal strategy is proposed to obtain porous carbon with rich carbon vacancies, high sp2 hybridized C content (65.3%), and large interlayer spacing using coal tar pitch as carbon precursor. Carbon vacancies and sp2 hybridized C are proved to be not only active sites for low‐voltage potassium storage but also conducive to the fast transfer of ions and electrons, endowing reversible and fast potassium storage at low voltage. Moreover, abundant carbon vacancies and large carbon interlayer spacing alleviate volume variation, improving the cycling stability for 8500 cycles (about 3700 h). This work sheds new light on the design of low‐voltage, durable, and fast potassium storage carbon anodes, and promotes the development of practical carbon anodes for high energy density K‐ion batteries in the future.

Volatile acetic acid selective adsorption by biomass-derived activated carbon with humidity-resistance: Tunable implanting and activation approach of activator

The selective adsorption and capture of polar organic acid gas by activated carbon (AC) absorbent could solve the challenge of irritant volatile organic compound discharge. However, volatile acid gas selective adsorption by traditional activated carbon with humidity resistance remains challenged. In this study, we developed an innovative one-step chemical synthesis method using discarded banana peels as a carbon source to create porous carbon materials. The selection of activators including sodamide and potassium hydroxide along with tunable implanting means of activator under different activated temperatures were modulated to optimize the fabrication of activated carbon. The results reveal that the low dosage of NaNH2 activator (NaNH2/carbon precursor = 1) implanted into carbon precursor through one-step ball-milling could contribute an excellent structural properties, and higher activated temperature makes the mesoporous behavior of activated carbon more obvious. Based on various optimization conditions, the optimal sample, BAC900, displays remarkable structural features (SBET = 2302 m2/g, Vtotal = 1.968 cm3 g−1, V>2nm = 1.474 cm3 g−1), achieving exceptional acetic acid adsorption efficiency (24.105 mmol g−1). Comparative analysis under various synthetic conditions revealed a close linear relationship between the structural characteristics (total pore volume) of adsorbent and acetic acid adsorption efficiency. We further explored the role of mesopores in facilitating acetic acid adsorption at relatively high pressures and their contribution to enhancing the hydrophobicity of the adsorbent. Additionally, we employed the Differential Isothermal Heat (DIH) technique to predict adsorption selectivity at varying relative humidity, revealing the higher adsorption heat (57 kJ mol−1) of acetic acid compared to water vapor (36 kJ mol−1). This comprehensive study emphasizes the outstanding adsorption selectivity of adsorbent for acetic acid, even in humid environments. Furthermore, the low adsorption heat of the BAC900 indicates good reversibility and reusability, paving the way for the practical application of biomass-derived functional biochar adsorbents in the environmental management of threatening acid VOCs pollutants.

Fabrication of Soft-Hard Heterostructure Porous Carbon with Enhanced Performance for High Mass-Loading Aqueous Supercapacitors.

With the increasing attention to energy and environmental issues, the high value-added utilization of biomass and pitch to functional carbon materials has become an important topic in science and technology. In this work, the soft-hard heterostructure porous carbon (NRP-HPC) is prepared by bio-template method, in which biomass and pitch are used as hard carbon and soft carbon precursors, respectively. The prepared NRP-HPC-4 shows high specific surface area (2293m2g-1), suitable pore size distribution, good conductivity (0.25Ωcm-1), and strong wettability. The synergistic effect of soft carbon and hard carbon ensures the composite material exhibiting excellent electrochemical performance for high mass loading (12.0mgcm-2) aqueous supercapacitor, i.e., high specific capacitance (304.69Fg-1 at 0.1Ag-1), high area capacitance (3.67Fcm-2 at 0.1Ag-1), high volumetric specific capacitance (202.74Fcm-3 at 0.1Ag-1), low open-circuit voltage attenuation rate (21.04mVh-1), good voltage retention (79.12%), and excellent cyclic stability (92.04% capacitance retention and 100% coulombic efficiency after 20000 cycles). The composite technology of soft carbon and hard carbon not only ensures the prepared porous carbon electrode materials with enhanced electrochemical performance, but also realizes the high value-added coupling utilization of biomass and pitch.

Balancing microcrystalline domains in hard carbon with robust kinetics for a 46.7 Wh kg−1 practical lithium-ion capacitor

As a promising electrochemical energy storage system, lithium-ion capacitors (LICs) exhibit alluring theoretical merits of high energy density, high power density and long cycle life. However, most of the LIC cells can hardly surpass the practical energy density threshold of 30 Wh kg−1, which greatly hinders their employments in various energy-oriented fields. Anthracite shows great prospect as low-cost and abundant carbon precursor to prepare anode material with plentiful Li-ion anchoring sites for high performance LICs. In this work, a scalable low-temperature hydrothermal disordering strategy is proposed to achieve balanced structural modification of anthracite into short-ranged turbostratic carbon precursor, which further transforms into microcrystalline hard carbon (MHC) with high electrical conductivity (13065 S m−1) and substantially improved energy storage kinetics. A practical large-capacity LIC pouch cell is fabricated using MHC anode and activated carbon cathode to deliver a maximum gravimetric and volumetric energy density of 46.7 Wh kg−1 and 66.8 Wh/L based on the total weight of cell, outperforming the commercially available LIC products from relevant enterprises. Moreover, the cell reveals an exceptional capacity retention of 94.7 % after 10,000 cycles at high current density. The work herein would emerge as a universal and feasible protocol to fabricate high-end carbon electrode for practical LICs in numerous energy-intensive occasions.

Pioneering the direct large‐scale laser printing of flexible “graphenic silicon” self‐standing thin films as ultrahigh‐performance lithium‐ion battery anodes

AbstractRecent technological advancements, such as portable electronics and electric vehicles, have created a pressing need for more efficient energy storage solutions. Lithium‐ion batteries (LIBs) have been the preferred choice for these applications, with graphite being the standard anode material due to its stability. However, graphite falls short of meeting the growing demand for higher energy density, possessing a theoretical capacity that lags behind. To address this, researchers are actively seeking alternative materials to replace graphite in commercial batteries. One promising avenue involves lithium‐alloying materials like silicon and phosphorus, which offer high theoretical capacities. Carbon–silicon composites have emerged as a viable option, showing improved capacity and performance over traditional graphite or pure silicon anodes. Yet, the existing methods for synthesizing these composites remain complex, energy‐intensive, and costly, preventing widespread adoption. A groundbreaking approach is presented here: the use of a laser writing strategy to rapidly transform common organic carbon precursors and silicon blends into efficient “graphenic silicon” composite thin films. These films exhibit exceptional structural and energy storage properties. The resulting three‐dimensional porous composite anodes showcase impressive attributes, including ultrahigh silicon content, remarkable cyclic stability (over 4500 cycles with ∼40% retention), rapid charging rates (up to 10 A g−1), substantial areal capacity (>5.1 mAh cm−2), and excellent gravimetric capacity (>2400 mAh g−1 at 0.2 A g−1). This strategy marks a significant step toward the scalable production of high‐performance LIB materials. Leveraging widely available, cost‐effective precursors, the laser‐printed “graphenic silicon” composites demonstrate unparalleled performance, potentially streamlining anode production while maintaining exceptional capabilities. This innovation not only paves the way for advanced LIBs but also sets a precedent for transforming various materials into high‐performing electrodes, promising reduced complexity and cost in battery production.

Hydrothermally synthesized-nanoscale carbonated hydroxyapatite with calcium carbonates derived from green mussel shell wastes

A hydrothermal method for exploring the benefits of a low-cost calcium carbonate precursor generated by mineral carbonation of green mussel wastes was in the study for synthesizing carbonated hydroxyapatite at various temperatures. Two typical precipitated calcium carbonates identified include vaterite and calcite particles formed by previous direct mineral carbonation. The hydrothermal assisted solution at an initial pH of 5–6, containing calcium carbonate precursor and diammonium hydrogen phosphate with a Ca/P ratio of 1.67, was autoclaved for carbonated hydroxyapatite (CHA) growth for 24 h at 50, 70, 90, and 110 °C and then allowed to air cool naturally. The hydrothermally obtained powder was subjected to additional analytical evaluation, including XRD, FTIR, and SEM/EDX analysis, providing that the crystal structure, carbonate content, and lattice constants of the A- and B-type CHA formed by varying hydrothermal temperature agreed very well with the A- and B-type carbonated hydroxyapatite as reported in the literature. The hydrothermal process could produce more than 90 wt.% of hydroxyapatite nanoparticles (17–26 nm) with minor monetite and calcite. These experimental findings may aid in synthesizing A- and B-type CHA for medical applications such as bone and enamel.

Nitrogen-oxygen co-doped carbon@silica hollow spheres as encapsulated Pd nanoreactors for acetylene dialkoxycarbonylation

The introduction of heteroatoms into hollow carbon spheres is imperative for enhancing catalytic activity. Consequently, we investigated the utilization of nitrogen–oxygen(N/O) co-doped hollow carbon (C)/silica (SiO2) nanospheres (NxC@mSiO2), which have a large internal volume and a nano-constrained environment that limits metal aggregation and loss, making them a potential candidate. In this study, we demonstrate the synthesis of nitrogen–oxygen (N/O) co-doped hollow carbon spheres using resorcinol and formaldehyde as carbon precursors, covered with silica, and encapsulated with palladium nanoparticles (NPs) in situ. The N/O co-doping process introduced defects on the surface of the internal C structure, which acted as active sites and facilitated substrate adsorption. Subsequent treatment with hydrogen peroxide (H2O2) introduced numerous carboxyl groups onto the C structure, increasing the catalytic environment as acid auxiliaries. The carboxyl group is present in the carbon structure, as determined calculations based on by density functional theory, reduces the adsorption energy of acetylene, thereby promoting its adsorption and enrichment. Furthermore, H2O2-treatment enhanced the oxygen defects in the carbon structure, improving the dispersion of Pd NPs and defect structure. The Pd/NxC@mSiO2-H2O2 catalysts demonstrated outstanding performance in the acetylene dialkoxycarbonylation reaction, showcasing high selectivity towards 1,4-dicarboxylate (>93 %) and remarkable acetylene conversion (>92 %). Notably, the catalyst exhibited exceptional selectivity and durability throughout the reaction.