Graphite-like Structure Research Articles

Resolving the enhancement effect of microwave-assisted pyrolysis on biochar redox properties from the structure-activity relationship

Biochar as a redox-active substance engaged in biogeochemical redox processes has received widespread attention in recent years. In this study, microwave-assisted pyrolysis (MWP) was found to have a significant enhancement effect on electron accepting capacity (EAC) and electron exchange capacity (EEC) of biochar, and the enhancement effect was further resolved by the constructed structure-activity relationship between structural compositions and redox properties. The results illustrated that the enhancement effect was mainly because MWP could significantly enhance the specific surface area (SSA), improving the formation of quinone and favouring graphite-like structures' lateral and longitudinal growth. In addition, based on the structure-activity relationship, this work also provides detailed suggestions for regulating the redox properties of biochars. For EAC, quinone had a more significant effect on EAC than electron donating capacity (EDC), and improving biochar skeleton structural properties such as La, Lc, and unsaturation degree was also effective in enhancing EAC. However, for EDC, introducing O-containing functional groups such as C-OH, CO, or the improvement of La in the biochar structure was more practical. Especially, improving the SSA positively affected both EDC and EAC, while opposite the average pore size.

High-performance carbon molecular sieve membrane for C2H4/C2H6 separation: Molecular insight into the structure-property relationships

Carbon molecular sieve (CMS) membranes show attractive potential for energy-efficient separation of C2H4/C2H6 due to their unique slit-like pore structure. In this work, a novel precursor polymer of phenolphthalein-based poly(arylene ether ketone) (PEK-C) was introduced to prepare high-performance CMS membranes for C2H4/C2H6 separation. Molecular insight into the effect of the sp3/sp2 hybridized carbon ratio on the packing morphology of carbon layers, pore size and configuration, and C2H4/C2H6 diffusion and separation properties of CMS membranes was investigated via using in-depth characterization techniques combined with molecular simulations. Results show that the carbon layers with more sp3 hybridized carbons lead to forming a loose and disordered carbon structure and pore structure with large pore volume and micropore size (steric voids), resulting in low C2H4/C2H6 permselectivity of CMS membrane. With the reduction of the sp3/sp2 hybridized carbon ratio, a compact and graphite-like carbon structure with the two-dimensional slit-like ultramicropore structure is formed, and the C2H4/C2H6 permselectivity is obviously enhanced. The CMS membranes derived from the novel precursor of PEK-C exhibit high C2H4 permeability with superior C2H4/C2H6 selectivity, which have surpassed the trade-off bounds of both polymeric membrane and CMS membrane, and reveal a great potential in the industrial applications of C2H4/C2H6 separation.

Carbon supported "core-shell structure" of Fe nanoparticles for enhanced Fenton reaction activity and magnetic separation.

Effectively facilitating Fe3+/Fe2+ cycles and expanding its operating pH range are keys to optimizing the traditional Fenton reaction. In this exploration, we used chitosan and ferrous sulfate as precursors to prepare a multicomponent magnetic Fe/C Fenton-like catalyst, which exhibited extraordinary catalytic properties and excellent stability performance in a pH range of 4~8. Besides, it could be easily separated from the solution by a magnet. The characterization showed that the supported Fe species include troilite-2H (FeS), lepidocrocite (FeOOH), and pyrrhotite-6T (Fe1 - xS) with a unique "core-shell structure." The presence of reductive iron sulfide core in the system can accelerate the reduction of Fe(III). Meanwhile, the graphite-like structure formed after calcination can adsorb and enrich priority pollutants near the active site through π-π coupling and strengthen electron transfer, which endows its high catalytic performance and enables it invulnerable to dissolved organic compounds.

Acid-mediated synthesis coupled with liquid–liquid extraction separation for obtaining red and orange double-color carbon dots: Application for pH, water sensing and cell-imaging

Owing to their various advantages, such as low photodamage and high tissue penetration, carbon dots (CDs) with long emission wavelength have gained much attention, and are used to compensate for blue to green fluorescent CDs. However, their synthesis has been challenging. In the present study, an acid-mediated synthesis method was developed for the preparation of long-wavelength CDs by using N-phenyl-o-phenylenediamine as a precursor, phosphoric acid as an acidity regulator. According to the principle of similarity compatibility, liquid–liquid extraction was further adopted to separate red CDs (R-CDs) and orange double-color CDs (O-CDs) from long-wavelength CDs mixture for the first time. By optimizing the factors that affect quantum yield (QY), R-CDs with a QY of 4.16% and O-CDs with a QY of 60.80% were obtained. Structural analysis revealed that both types of CDs had a graphite-like structure with an abundance of various groups on their surface. Their fluorescence colors were quite different because of differences in the nature of these functional groups (e.g. contents of N and P). To explore the application value of two kinds of CDs, the potential use of R-CDs, for pH sensing and O-CDs for water content detection in organic solvents was studied systematically. The results revealed that R-CDs was acid sensitive and can be used to detect different pH values. While O-CDs can be used for the detection of various water content in different organic solvents including ethyl acetate, ethanol, methanol, DMSO, DMF and acetone. Finally, due to the low toxicity and good biocompatibility, the potential of R-CDs as probe for cell imaging was explored preliminarily. Co-localization experiments with commercial dye Lyso-tracker Red showed that R-CDs was localized in lysozyme and can be used for lysosomal imaging, further proving that R-CDs is a potential lysosomal probe.

Study on the deactivation mechanism of HZSM-5 in the process of catalytic cracking of n-hexane

The coke deactivation over HZSM-5 zeolites with different Si/Al ratios in the n-hexane cracking reaction was studied in 200 h of reaction. In the products, alkanes, C2=, C3=, C4= and aromatic compounds such as benzene, toluene, and xylene (BTX) were formed. The selectivity variations of C3= and C4= were inverse proportional to that of BTX, indicating that C3= and C4= intermediates were the precursors of BTX compounds. The internal coke was preferentially formed inside zeolite micropores in the initial reaction period (0–70 h), which significantly diminished the micropore volume, covered the strong acid sites, and strongly inhibited catalytic activity of the catalysts with lower Si/Al ratio. The external coke was principally formed after 70 h of reaction and had a less influence on the catalytic activity. The internal coke (density 1.03 g·cm−3 and a H/C ratio of 1.16) could be effectively removed by H2 treatment at 850 °C; while the external coke (density 1.46 g·cm−3 and a H/C ratio of 0.28) with graphite-like structure resisted H2 treatment. For the zeolites with low Si/Al molar ratio (25 and 50), the rapid coking stage (0–70 h) occurred at high n-hexane conversion followed by a slow deactivation stage at low conversion (70–200 h); for zeolites with high Si/Al molar ratio (85 and 130), a very slow deactivation stage took place in the reaction period (0–70 h), followed by a faster deactivation stage (70–200 h). This work demonstrated that zeolite deactivation behavior was correlated not only with the strong acid sites and microporosity of catalyst, but also affected by the location, amount, structure, and type of coke. The mechanisms for internal and external coke formation and H2 decoking strategy for the deactivated catalyst regeneration were discussed and proposed.

Novel Ca and Ca-Li Intercalated B/C and B/C/N Materials with Layered Structures

Abstract Boron/carbon/nitrogen (B/C/N) materials and boron/carbon (B/C) materials having graphite-like layered structures were synthesized by using a chemical vapor deposition (CVD) method. Calcium (Ca) was intercalated into the B/C materials by the reaction of Ca vapor with the host B/C film to form an intercalation compound with a second stage structure as a main product. Ca was also co-intercalated with lithium (Li) into the B/C/N materials by using a liquid-alloy method to form an intercalation compound. These are the first examples of syntheses of Ca and Ca-Li intercalated B/C and B/C/N materials. A nuclear microprobe analysis (NMA) indicated the compositions of the original host B/C/N and B/C materials to be BC2.6N0.55 and BC6.4, and the Ca-Li intercalated compound to be Ca0.67Li0.42(BC3.3N0.50) and suggested the homogeneity of these materials and the compound. We also found that the NMA is one of the most accurate methods for determining the compositions of air and water sensitive intercalation compounds as well as complex systems like B/C/N and B/C materials.

RGO/Li-Al-LDH composite nanosheets modified commercial polypropylene (PP) separator to suppress lithium dendrites for lithium metal battery

Lithium metal batteries (LMBs) with ultra-high theoretical energy density are a prospective candidate to replace current lithium-ion batteries (LIBs). However, there are still two non-negligible problems of lithium dendrites and the volume expansion effect of LMBs. In this study, reduced graphene oxide (rGO)/Li-Al-LDH composite nanosheets were firstly prepared via a hydrothermal method and then vacuum filtered onto commercial polypropylene (PP) separator. This kind of rGO/Li-Al-LDH nanosheets layer is expected to improve the wettability of liquid electrolytes and thermal stability. Furthermore, rich- Li-Al LDH can promote more ionic carriers and channels, which exhibits higher-efficiency lithium-ion transport properties. Meanwhile, rGO with a graphitic-like structure is able to disperse the concentration of electrons at the sharp point when lithium dendrites arise. As a result, the discharge capacity of the Li||LiFePO4 cells based on the rGO/Li-Al-LDH@PP separator is still 1.852 mAh after 250 cycles and the capacity decay rate is just 4.24%. It is demonstrated that a feasible and effective strategy for the modified separator can enhance the electrochemical performance of LMBs.

Preparation of sulphuric acid-mediated N,S-codoped red emissive carbon dots: Applications in food dyes detection, solid-state luminescence and cell imaging

As diseases such as cardiovascular disease and cancer caused by food problems are more and more frequent, food safety has received great attention. Among them, the safety problem caused by food dyes is more prominent. Thus, it is of great value to develop sensitive detection methods for food dyes. In present study, sulphuric acid-mediated N,S-codoped red emissive carbon dots (namely as R-CDs) had been manufactured by using N-phenyl-o-phenylenediamine as precursor, sulfuric acid as additive for the first time. The structural and fluorescence properties of R-CDs had been systematically studied. The results demonstrated that R-CDs showed uniform spherical morphology and had a graphite-like structure, for which the average diameters size was 5.05 nm. Due to the various functional groups such as hydroxyl, pyridinic N, pyrrolic N and -C-SO4, R-CDs emitted bright red fluorescence. Importantly, because of the interactions between the functional groups of R-CDs with the selected food dyes, three dyes including amaranth, brilliant blue FCF and methylene blue can sensitively quench the fluorescence of R-CDs through IFE and static quenching effects. The linearity ranges of them were separately detected as 0.20 μM −20 μM, 10 nM-1 μM and 60 nM-8 μM. The limits of detection (LODs) of them were 70 nM, 4 nM and 20 nM, respectively. Further, R-CDs was successfully applied to the sensitive detection of three dyes from various food samples. To maximize the fluorescence properties of R-CDs, a R-CDs/PVA composite gel was fabricated to make R-CDs fluoresce in solid state condition. The potential of R-CDs/PVA composite gel for preliminary visualization analysis of three dyes was studied. Finally, ascribed to the low toxicity and good biocompatibility, the potential of R-CDs as probe for cell imaging was explored preliminarily.

A comprehensive study on the effect of carbonization temperature on the physical and chemical properties of carbon fibers

Carbon fibers were successfully fabricated via the electrospinning technique, followed by stabilizing and carbonizing electrospun PAN fibers. A wide range of analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), vibrating sample magnetometer (VSM) techniques, and Hall effect were performed to study of the effect of carbonization temperature on the physical and chemical characterization of carbon fibers. The SEM images of the PAN precursor exhibit a smooth outer surface, after the stabilization and carbonization process, along with a broken fiber at higher carbonization temperature about 1400 °C. Morphological characterization based on the recorded TEM images of carbonized fibers at 1000 °C and 1400 °C, showed that the obtained morphology can be classified as fiber structures, where their diameters ranged from 196 to 331 nm. The XRD patterns of PAN-based carbon fibers confirm the structural changes from linear structure into a graphite-like structure. The DRS study indicates the possible π–π*/σ–π* and n–π* transitions. The presence of the surface functional groups and different trapped radiative recombination on the emission bands is confirmed by the PL. VSM results shows the weak ferromagnetic nature of the carbon fibers.

(Oxy)nitride heterojunction-strengthened separation of photogenerated carriers in g-C3N4 towards enhanced photocatalytic H2 evolution

The metal-free graphitic carbon nitride (g-C3N4) with a series of merits like low cost, favorable stability, and controllable two-dimensional graphite-like structure, has been extensively studied for photocatalytic H2 evolution. Composite engineering is regarded as one of effective strategies to adjust the kinetics of photogenerated carriers in g-C3N4 for elevating its photocatalytic performance. Herein, the composite system of g-C3N4 with oxynitride LaTiO2N was elaborately constructed for improving photocatalytic H2-evolution performance. With systematical characterizations, the partial cover of g-C3N4 nanosheets on LaTiO2N (LaTiO2N@g-C3N4) was verified and promoted the sufficient contact between g-C3N4 and LaTiO2N, accompanied by the formation of the (oxy)nitride heterojunction. Benefited by the well-matched band structures for g-C3N4 and LaTiO2N, the (oxy)nitride heterojunction strengthened the separation of photogenerated carriers and therefore enhanced the photocatalytic performance of g-C3N4. This work gives more insight in composite engineering on g-C3N4, and also provides feasible guidelines for designing g-C3N4-based photocatalysts towards improving photocatalytic performance.

Two-dimensional coronene fractal structures: topological entropy measures, energetics, NMR and ESR spectroscopic patterns and existence of isentropic structures

Molecular fractals are geometric patterns that appear self-similar across all length scales and are constructed by repeating a single unit on a regular basis. The benzenoid compounds are found to have a natural pattern that helps to analyse and explore the potential attributes of these molecular fractals. Here, we focus on coronene-based fractals where coronene is a benzenoid molecule with a symmetric graphite-like structure and challenging synthesis methods. Topological molecular descriptors are obtained in order to provide structure-activity relations for the physico-chemical properties. We obtain these descriptors for the molecular fractals that are constructed by repeating a fixed unit of coronene on different stages systematically. The structural characterisation of the two-dimensional coronene fractals in various tessellations is presented through a wide range of degree-based topological indices. The entropy measures of these significant frameworks are also computed for estimating their potential attributes, and the comparison of their values among various degree-based indices is performed, which shows the existence of isentropic structures. We have developed machine learning techniques for robust computations of the enthalpies, NMR and ESR spectroscopic patterns of coronene fractals.

Evaluation of graphitization and tensile property in microwave plasma treated carbon fiber

Plasma technology can be used as a green and novel method for the graphitization of carbon fiber. The effect of graphitization time on the main element content along with microstructure of carbon fiber in the plasma treatment process was investigated. It took an extremely short time (less than 100 ms) for the temperature of the system to increase until a relatively stable stage was reached. Furthermore, compared with the original carbon fiber, the increase in the carbon content and graphitization degree of carbon fiber was observed after microwave plasma treatment. Moreover, the original imperfect turbostratic graphite-like structure transformed to an ordered graphite structure with the escape of non‑carbon elements from the disordered region of graphite-like crystallites. With the graphitization time of 180 s and microwave power of 800 W, corresponding to the temperature of 2100 °C, a high graphitization degree (R = 0.61) was observed and the crystallite size was as large as 5.10 nm, which are better than that of M40J and T800H. After 5 mins treatment, the average tensile modulus of samples apparently increased by 23% from 189 GPa to 245 GPa. This work demonstrated that the microwave plasma is an alternative approach for the development of carbon fibers with good microstructure and high graphitization degree.

An Innovative Microwave-Assisted One-Step Green Synthetic Approach of Biowaste Derived Fluorescent Carbon-Dot Invisible Ink for Currency Anti-Counterfeiting Applications

The quest for the design and synthesis of carbon dots with anti-counterfeit properties that are derived via green, environmentally friendly and economical procedures is a continuous process. Carbon dots (C-dots) derived from biowaste are cheap to synthesize, possess good photo-stability and high synthetic yield, making them applicable in the anti-counterfeiting of currency. Herein, we report a novel eco-friendly, cheaper, and faster method for the synthesis of carbon dots with strong photoluminescence properties from monkey orange fruit (Strychnos spinosa) biowaste. The presence of the hydroxyl and carbonyl functional groups of the carbon dots were determined by the Fourier transform infrared spectroscopy (FTIR). The carbon dots showed strong blue emission fluorescence (emission wavelength of 452[Formula: see text]nm) when excited at 330[Formula: see text]nm. The morphology and size were determined by the atomic force microscopy (AFM) which indicated amorphous and spherical nanoparticles with an average size of less than 2[Formula: see text]nm. The no-crystallinity of the as-prepared carbon dots was confirmed using X-ray diffraction which showed the graphite-like structure. The carbon dots were produced and demonstrated good photo and chemical stability as well as high covert properties. The anti-counterfeiting of currency application by the synthesized carbon dots was demonstrated when the subsequent gel ink printed on the currency showed excellent chemical stability when exposed to washing with water, ethanol, and acetone. It also showed superior photostability when exposed to UV light at 365[Formula: see text]nm and daylight for an extended period of up to 6[Formula: see text]h. This work provides a facile, economical, and green approach for large scale production of carbon dots from the abundant biowaste.

Green preparation and supercapacitive behaviors of calcium carbide derived porous carbon based on solvent-free mechanochemical route

Carbide-derived carbon (CDC) as a late-model type of porous carbon material has become a potential electrode material for supercapacitor. However, the preparation methods of Cl2 etching and electrochemical etching are environmentally unfriendly and extremely difficult for large-scale production. Thus, exploring a simple and environmentally friendly synthetic method of CDC materials is very imperative. In this work, calcium carbide derived porous carbon (CCDPC) is successfully synthesized through solvent-free mechanochemical reaction. The results show that the CCDPC is a kind of micro-mesoporous combination material with layered structure, partial graphite-like structure and high specific surface area of 525.3 cm2 g−1. It has been found that the as-prepared electrode possesses a better electrochemical performance in 1 M KOH electrolyte, and the specific capacitance reaches up to 205.4 F g−1 at current density of 0.5 A g−1. Furthermore, the assembled symmetric supercapacitor displays a high cycle stability, the capacitance retention still remains 93% after 30,000 cycles. Therefore, the preparation strategy of CCDPC with excellent electrochemical properties through a simple mechanochemical reaction provides an innovative synthetic idea for the preparation of calcium carbide derived carbon materials for the application of supercapacitors.

Synthesis and Characterization of Graphite Intercalation Compounds with Sulfuric Acid

In this work, graphite intercalation compounds (GICs) were synthesized using three different oxidizers: (NH4)2S2O8, K2S2O8, and CrO3 with and without P2O5 as a water-binding agent. Furthermore, the samples obtained were heat-treated at 800 °C. Specimens were characterized by optical microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The correlation between different characteristic parameters of the Raman analysis has shown that the use of CrO3 results in a much higher structural disorder compared to the products obtained using persulfate oxidizers. Narrowing the correlation set revealed that minimal defect concentration can be reached by using K2S2O8, while the use of (NH4)2S2O8 causes a slightly higher concentration of defects. It was also established that the additional use of P2O5 can help to achieve more effective intercalation and has a positive effect on the formation of the stage I GIC phase. After heat treatment, the intercalated products mostly return to a graphite-like structure; however, the samples obtained with CrO3 stand out with the most significant changes in their surface morphology. Therefore, analysis suggests that GICs obtained using persulfate oxidizers and P2O5 could be a candidate to produce high-quality graphene or graphene oxide.

Heterometallic Benzenehexathiolato Coordination Nanosheets: Periodic Structure Improves Crystallinity and Electrical Conductivity.

Coordination nanosheets are an emerging class of 2D, bottom-up materials having fully π-conjugated, planar, graphite-like structures with high electrical conductivities. Since their discovery, great effort has been devoted to expand the variety of coordination nanosheets; however, in most cases, their low crystallinity in thick films hampers practical device applications. In this study, mixtures of nickel and copper ions are employed to fabricate benzenehexathiolato (BHT)-based coordination nanosheet films, and serendipitously, it is found that this heterometallicity preferentially forms a structural phase with improved film crystallinity. Spectroscopic and scattering measurements provide evidence for a bilayer structure with in-plane periodic arrangement of copper and nickel ions with the NiCu2 BHT formula. Compared with homometallic films, heterometallic films exhibit more crystalline microstructures with larger and more oriented grains, achieving higher electrical conductivities reaching metallic behaviors. Low dependency of Seebeck coefficient on the mixing ratio of nickel and copper ions supports that the large variation in the conductivity data is not caused by change in the intrinsic properties of the films. The findings open new pathways to improve crystallinity and to tune functional properties of 2D coordination nanosheets.

In situ wide-angle X-ray scattering study on the change of microcrystalline structure in Jincheng anthracite during high-temperature carbonization

Carbonization is an effective way to achieve the comprehensive utilization of coal. However, the in situ variation of graphite-like microcrystals, the basic structure of coal macromolecules, with heating and cooling during carbonization has not been fully characterized so far. Anthracite is a type of humic coal with the highest degree of coalification, and its structure change can be monitored well by X-ray scattering or diffraction techniques. In this contribution, an in situ synchrotron radiation wide-angle X-ray scattering (WAXS) study on high-temperature (1200°C) carbonization of a high-quality anthracite mined in Jincheng, China, is presented. The results show that, during the continuous process of heating and cooling, the size and height of the aromatic lamellae first decrease and then increase with minima at 900 and 1000°C, respectively, while the interlayer spacing first increases and then decreases with a maximum at 1000°C. The roadmap of graphite-like microcrystalline structure change during the whole continuous process of heating and cooling is revealed and described.

Comparison of properties, adsorption performance and mechanisms to Cd(II) on lignin-derived biochars under different pyrolysis temperatures by microwave heating

The application of biochar derived from various biomass to treat heavy metal pollution has received particular attention in recent years. Lignin is an abundant, highly aromatic byproduct from the paper-making industry with a low utilization rate, which is a potential feedstock for biochar preparation. In this study, lignin was carbonized at different temperatures by microwave heating to obtain biochars (LBx), and the effect of pyrolysis temperature on biochar properties, Cd(II) adsorption behavior, and mechanisms was comprehensively investigated. It was found that the biochar-inherent minerals gradually enriched, the surface functional groups decomposed, and more structural defects formed at the edges of graphite-like structures with the increasing pyrolysis temperature. Adsorption experiments demonstrated that the adsorption capacity of lignin improved significantly after carbonization. And as the temperature increased from 200 °C to 500 o C, the q m of LBx increased from 573.27 to 635.44 mg ⋅ g −1 , which were vastly superior to common reported biochars. The adsorption mechanisms of Cd(II) on the LBx can be classified into the interaction with dissolved fractions (biochar-inherent minerals co-precipitation and DOM interaction) and bulk biochar (surface complexation and ionic exchange). The quantitative mechanisms indicated that the dissolved matters contribute more to Cd(II) adsorption than bulk biochar, but the contribution decreased from 89.48% to 77.38% with increasing temperature. Surface complexation and ionic exchange are two dominant mechanisms on bulk biochar, and the former has a more significant advantage for higher-temperature prepared biochar. Taken together, lignin was an efficient and promising feedstock to prepare biochar used for Cd(II) removal. • A low-cost biochar was directly prepared with industrial lignin by microwave heating. • LBs showed excellent adsorption performance to Cd(II) than common reported biochars. • Dissolved matters and bulk biochar on LBs both play important role in Cd(II) removal. • Surface complexation dominated the adsorption of higher-temperature bulk biochars.

Removal of tetracycline onto KOH-activated biochar derived from rape straw: Affecting factors, mechanisms and reusability inspection

A porous biochar (BC) was prepared using the recycled agricultural waste rape straw as resources by combining high temperature carbonization with KOH activation procedure, and applied into tetracycline hydrochloride (TC) adsorption. The multiple characteristic techniques were adopted to investigate the structures and properties of as-prepared BC. The results demonstrated that the BC activated by KOH would possess the more graphite-like structures, more abundant oxygen-containing functional groups, and larger specific surface area (1531 m2/g) comparing with unactivated BC, which were favorable for the TC adsorption. The effects of initial TC concentration, solution pH value, salt ionic strength and adsorption temperature on the adsorption performances were explored in detail. The adsorption data could be well fitted by the pseudo-second-order kinetic model and Freundlich isothermal model. The maximum adsorption capacity of KOH activation BC could reach 325.07 mg/g at 30 °C. The endothermic and spontaneous properties of the adsorption system was implied by thermodynamic study. The adsorption TC mechanism of KOH activation BC was involved in the pore filling, π-π electron donor-acceptor interaction, hydrogen bonding and electrostatic action. Regeneration experiments showed that the TC removal efficiency could still attain 97.0% even after six cycling experiment, suggesting that the BC had the excellent reusability and stability. These results indicate the feasibility of a win-win strategy for the application of agricultural waste to water remediation.

Electronic, Structural, and Magnetic Upgrading of Coal-Based Products through Laser Annealing.

Most coal-to-product routes require complex thermal treatment to carbonize the raw materials. However, the lack of unified comparison of products made from different kinds of coals downplays the role of initial coal chemistry in high-temperature reactions. Here, we used a CO2 laser to investigate the roles that aromatic content and maturity play in the structural evolution and doping of coals during annealing. Results show that a bituminous coal (DECS 19) with aromatic content and maturity in between higher rank, more mature anthracite (DECS 21) and lower rank, lower maturity lignite (DECS 25) leads to more graphite-like structure observed from the highest 2D peak on the Raman spectrum and conductivity (sheet resistance ∼30 ohm sq-1) after lasing. When nitrogen dopants are incorporated with saturated urea dopants into coals through laser ablation, nitrogen preferentially incorporates at the edge sites of graphitic grains. Furthermore, oxide nanoparticles can be incorporated into the graphitic backbone of coal to modify their electronic and magnetic properties through laser annealing. Leveraging tunable magnetic behavior, we demonstrate a soft actuator using both conductive and magnetic coal-Fe/Co oxide. Through laser annealing, we propose a paradigm to understand and control coal chemistry toward flexible and tunable doping and magnetism.