Carbonaceous Materials Research Articles

Adsorption Technology for PFAS Removal in Water: Comparison between Novel Carbonaceous Materials.

PFASs are a variety of ecologically persistent compounds of anthropogenic origin loosely included in many industrial products. In these, the carbon chain can be fully (perfluoroalkyl substances) or partially (polyfluoroalkyl substances) fluorinated. Their ubiquitous presence in many environmental compartments over the years and their long-lasting nature have given rise to concerns about the possible adverse effects of PFASs on ecosystems and human health. Among a number of remediation technologies, adsorption has been demonstrated to be a manageable and cost-effective method for the removal of PFASs in aqueous media. This study tested two novel and eco-friendly adsorbents (pinewood and date seeds biochar) on six different PFASs (PFOS, GenX, PFHxA, PFOA, PFDA, and PFTeDA). Batch sorption tests (24 h) were carried out to evaluate the removal efficiency of each PFAS substance in relation to the two biochars. All samples of liquid phase were analyzed by a developed and then a well-established method: (i) pre-treatment (centrifugation and filtration) and (ii) determination by high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS/MS). The results evidenced a comparable adsorption capacity in both materials but greater in the long-chain PFASs. Such findings may lead to a promising path towards the use of waste-origin materials in the PFAS remediation field.

Nonradical peroxymonosulfate activation via high-level pyrrolic-nitrogen and electron-deficient carbon at 2D ultrathin carbonaceous nanosheets for efficient BPA removal

Activation of persulfate by N-doped carbon is an emerging advanced oxidation process (AOP) for removing organic pollutants from water via singlet oxygen (1O2)-dominated non-radical way, however, the efficient generation of 1O2 is a hot topic worth deep exploration. In this study, glucose was used as an additional carbon and oxygen of prefabricated supramolecular melamine-cyanuric acid precursor, the final co-thermal polymerization products completely changed from conventional graphitic carbon nitride to ultrathin carbonaceous materials when the mass of glucose up to 0.72 g. The simple one-pot strategy can easily generate active electron-deficient carbon sites due to nitrogen and oxygen doping by modulating the electronic structure of the carbon framework, which is critical for the activation of peroxymonosulfate (PMS) to produce 1O2. The glucose content can adjust the degree of disorder of the amorphous carbonaceous nanosheet, and significantly improve the exposure of active pyrrolic nitrogen sites (27.47 %) and doped oxygen through the defective structure, which is another essential factor for the generation of 1O2 in the activation of PMS. The MCAG-0.72/ PMS exhibited excellent performance in BPA degradation, 95 % BPA (20 mg L−1) can be removed in 60 min with 1.0 mM PMS with reaction constant k=0.0209 min−1. Furthermore, MCAG-0.72 also demonstrated excellent BPA degradation in different actual water metrics and performance well in the four consecutive cycles. This study provides a novel convenient strategy to synthesize cost-effective N/O co-doped carbonaceous material for efficient activating PMS to remove refractory organics in water and wastewater, it sheds light on practical large-scale industrial applications in PMS-based AOPs.

Tubular-like Nanocomposites with Embedded Cu9S5-MoSx Crystalline-Amorphous Heterostructure in N-Doped Carbon as Li-Ion Batteries Anode toward Ultralong Cycling Stability.

Transition metal sulfides (TMSs) show the potential to be competitive candidates as next-generation anode materials for Li-ion batteries (LIBs) due to their high theoretical specific capacity. However, sluggish ionic/electronic transportation and huge volume change upon lithiation/delithiation remain major challenges in developing practical TMS anodes. We rationally combine structural design and interface engineering to fabricate a tubular-like nanocomposite with embedded crystalline Cu9S5 nanoparticles and amorphous MoSx in a carbon matrix (C/Cu9S5-MoSx NTs). On the one hand, the hybrid integrated the advantages of 1D hollow nanostructures and carbonaceous materials, whose high surface-to-volume ratios, inner void, flexibility, and high electronic conductivity not only enhance ion/electron transfer kinetics but also effectively buffer the volume changes of metal sulfides during charge/discharge. On the other hand, the formation of crystalline-amorphous heterostructures between Cu9S5 and MoSx could further boost charge transfer due to an induced built-in electric field at the interface and the presence of a long-range disorder phase. In addition, amorphous MoSx offers an extra elastic buffer layer to release the fracture risk of Cu9S5 crystalline nanoparticles during repetitive electrochemical reactions. Benefiting from the above synergistic effect, the C/Cu9S5-MoSx electrode as an LIB anode in an ether-based electrolyte achieves a high-rate capability (445 mAh g-1 at 6 A g-1) and superior ultralong-term cycling stability, which delivers an initial discharge capacity of 561 mAh g-1 at 2 A g-1 and its retention capacity after 3600 cycles (376 mAh g-1) remains higher than that of commercial graphite (372 mAh g-1).

Green carbon-based adsorbents for water treatment in Sub-Saharan Africa

Abstract As underlined by the United Nations Sustainable Development Goals (UN SDGs), providing safe and clean potable water remains a significant concern in developing regions of the world, especially Sub-Saharan Africa. Extensive research has been done on this subject in Africa. The concept of sustainable chemistry towards solving another pressing issue in Africa – waste management – led to the decision to investigate green carbon-based materials for water purification on the continent. The conversion of “waste to wealth” is a practical means of achieving proper waste management at a reasonable cost. Low-cost adsorbents such as biochar, activated carbons, graphene and carbon composites, with high surface area, porosity and efficiency have been generated from agricultural waste and biomass, carbon-rich geological materials, carbonaceous polymeric materials, and hydrocarbons/petroleum by-products, using simple thermal and/or green chemical reaction protocols. Several drawbacks have hindered the development and utilization of adsorbents for the treatment of polluted water, including chemical fouling, loss of activity, poor reusability, difficulty associated with sorbent regeneration, production of secondary pollutants, toxicities caused by exposure to sorbent residues, and inability to deal with heavily polluted water. However, the use of adsorbents is still widely acclaimed as an efficient and cleaner method among other existing water treatment options such as extraction, chemical oxidation, bioremediation, and photocatalytic degradation. This paper outlines the research carried out by Sub-Saharan African scientists to proffer solutions to water pollution using green carbon-based adsorbents and discusses the breakthroughs, challenges, and future prospects.

Facile and precise synthesis of core-shell ZnO/C nanorods with excellent microwave absorption

Carbonaceous materials have great prospects in microwave absorption due to their lightweight and corrosion resistance. However, their high conductivity leads to poor impedance matching, posing a significant challenge for obtaining outstanding microwave absorption (MA) materials from carbonaceous materials. In this work, the core-shell ZnO/C nanorods (ZCNs) are prepared by covering conductive carbon on the surface of ZnO nanorods through a simple stirring process in ambient temperature and calcination treatment. The thickness of carbon shell is carefully regulated to realize appropriate impedance matching and strong microwave dissipation capability. ZCN with 30.2 nm of carbon shell achieves outstanding microwave absorption in low frequency and broadband microwave absorption because of the synergies of optimized impedance matching and enhanced dielectric loss: the reflection loss of 49.9 dB at 6.32 GHz, and the effective absorption bandwidth of 6.4 GHz at a corresponding thickness of 2.0 mm. RCS simulation results have verified its excellent performance in practical application. This study proposes a simple and effective idea for the efficient utilization of carbonaceous materials in microwave absorption.

First-Principles Structure Search Study of 17-β-Estradiol Adsorption on Graphene.

17-Beta-estradiol (E2), a steroid hormone synthesized from cholesterol, has various impacts on health and the environment. Currently, the gold standard for its measurement in the body is a conventional blood test (mass spectrometry), but carbon-based electrochemical sensors have been proposed as an alternative due to their advantages, such as rapid analysis time and sensitivity. To improve the atomic-level understanding of the interactions at the substrate surface, we performed density functional theory (DFT) simulations to study the nature of the adsorption of E2 on pristine graphene. Bayesian Optimization Structure Search (BOSS) was employed to reduce human bias in the determination of the most favorable adsorption configurations. Two stable adsorption minimum configurations were found. Analysis of their electronic properties indicates that E2 physisorbs on graphene. Embarking upon complex carbonaceous materials, the importance of finding all possible minimum candidates with automated structure search tools is highlighted. Computational investigations facilitate tailoring substrate materials with outstanding performance and applications in neuroscientific research, fertility monitoring, and clinical trials. Combining them with experimental research carries significant potential to advance sensor design beyond the current state-of-the-art.

Accelerated First-Principles Exploration of Structure and Reactivity in Graphene Oxide.

Graphene oxide (GO) materials are widely studied, and yet their atomic-scale structures remain to be fully understood. Here we show that the chemical and configurational space of GO can be rapidly explored by advanced machine-learning methods, combining on-the-fly acceleration for first-principles molecular dynamics with message-passing neural-network potentials. The first step allows for the rapid sampling of chemical structures with very little prior knowledge required; the second step affords state-of-the-art accuracy and predictive power. We apply the method to the thermal reduction of GO, which we describe in a realistic (ten-nanometre scale) structural model. Our simulations are consistent with recent experimental findings, including X-ray photoelectron spectroscopy (XPS), and help to rationalise them in atomistic and mechanistic detail. More generally, our work provides a platform for routine, accurate, and predictive simulations of diverse carbonaceous materials.

Accelerated First‐Principles Exploration of Structure and Reactivity in Graphene Oxide

Graphene oxide (GO) materials are widely studied, and yet their atomic‐scale structures remain to be fully understood. Here we show that the chemical and configurational space of GO can be rapidly explored by advanced machine‐learning methods, combining on‐the‐fly acceleration for first‐principles molecular dynamics with message‐passing neural‐network potentials. The first step allows for the rapid sampling of chemical structures with very little prior knowledge required; the second step affords state‐of‐the‐art accuracy and predictive power. We apply the method to the thermal reduction of GO, which we describe in a realistic (ten‐nanometre scale) structural model. Our simulations are consistent with recent experimental findings, including X‐ray photoelectron spectroscopy (XPS), and help to rationalise them in atomistic and mechanistic detail. More generally, our work provides a platform for routine, accurate, and predictive simulations of diverse carbonaceous materials.

(Invited) The Role of Carbon in Enabling Stable Solid State Batteries

Carbonaceous materials are widely used as the anode materials in rechargeable lithium-ion batteries. In that context, they serve as the host for lithium ions. Their structural stability and limited volume changes underpin the long-term stability of the batteries. In solid-state batteries, however, their roles have evolved. With the focus on raising cell energy density and the promise of stable operation of lithium metal due to the absence of organic solvent, carbon has not been widely studied as an anode material. Unfortunately, the promise of lithium metal has encountered significant challenges: it chemical reacts with virtually all known solid state electrolytes; lithium also grows dendrites which can eventually lead to shorting; the stripping of lithium is also often inhomogeneous which had led to void formation at the interface. To address these challenges, carbonaceous materials have been reintroduced.In this talk, we overview several applications of carbonaceous materials in solid state batteries. We have shown that graphite can be engineered as a 3D host for lithium deposition. Lithiated graphite becomes lithiophilic with low nucleation barrier for lithium metal deposition. The voids between the graphite particles can accomodate lithium metal. As a result, the critical current density and cycling stability of both full cells and symmetric cells have greatly improved. We note that in this context, the anode is essentially a graphite electrode that experiences intentional overlithiation.In a second application, we show that carbon can serve as an effective interlayer between lithium and the solid electrolyte. This interlayer reduces the side reaction between lithium and the electrolyte, thus greatly improving the cycle life and coulombic efficiency. It is rather surprising that upon lithiation, the interlayer enables lithium transport and preferential lithium deposition at the carbon/lithium interface, rather than the carbon/electrolyte interface. This desirable outcome is observed despite the fact that the interlayer itself is electrically conducting. We studied a wide variety of carbon materials in terms of surface area, crystal structure, and defect density. With the optimized carbon material, critical current densities of over 30 mA/cm2 have been observed. The mechanism of lithium transport will be discussed along with the design criteria for using carbon as an effective mixed electron and ion conductor.

Dynamic Oxygen Collection Efficiency: Unraveling the Effects of Perovskites on Carbon Corrosion As Composite Catalysts for Oxygen Electrode

Introduction The composite catalyst comprising perovskite and carbon has been extensively studied as a catalyst for the oxygen evolution reaction (OER) at the oxygen electrode in alkaline media. However, the competitive corrosion of carbon under harsh OER potential necessitates additional caution when determining OER activity from the overall oxidation current. The use of a rotating ring-disk electrode (RRDE) is acknowledged for its ability to quantitatively determine the faradaic efficiency of the OER. [1] However, for practical applications, the generation of oxygen bubbles can cause unpredictable disturbance, leading to the erroneous collection efficiency. In this study, we aim to establish a dynamic current-response collection efficiency during the generation of oxygen bubbles. This was achieved by modelling with an Au/Au RRDE, well-known for its electrochemical stability under harsh conditions. In addition, using this calibrated collection efficiency, we investigate the influence of perovskite catalysts on the degradation behaviors of carbon materials at OER potentials in alkaline media. Materials and electrochemical measurements Measurements of oxygen gas collection efficiency were conducted using a modeled RRDE comprising an Au disk electrode and an Au ring electrode. The RRDE served as the working electrode, with a Pt wire as the counter electrode, a reversible hydrogen electrode (RHE) as the reference electrode, and a solution of Ar-saturated 1 mol dm-3 KOH as the electrolyte. The disk electrode underwent a 5-minute chronopotentiometry with varied oxidation currents, while the ring electrode underwent chronoamperometry at 0.3 V (vs. RHE). The collection efficiency was calculated from the ring current attributed to the oxygen 2-electron reduction reaction.Two kinds of perovskite catalysts, namely Sr2Co0.8Fe0.2O3Cl[2] (hereafter SCFOC) and LaCoO3 (hereafter LCO), and two carbonaceous materials, namely graphitized carbon black (TOKABLACK#3845, hereafter TB) and ketjen black (EC-600JD, hereafter KB), were used to evaluate the influence of perovskite on the carbon degradation behavior. Four composite catalysts, each comprising perovskite and carbon with a weight ratio of 5:1, were loaded on a disk electrode of the glassy carbon disk/Au ring RRDE. A cell analogous to the aforementioned design was assembled. Electrochemical measurements were conducted through chronoamperometry, employing various potentials at the disk electrode, and maintaining a potential of 0.3 V vs. RHE at the ring electrode, for a duration of 5 minutes. Results and discussion Figure 1 illustrates a three-dimensional representation of the oxygen gas collection efficiency of the Au/Au RRDE as two functions of disk current density and measurement time. It was evident that the oxygen gas collection efficiency varied significantly from the theoretical value (25.6 %) and was dependent on the disk current density and measurement time. The constrained solubility of oxygen in aqueous solution and the hydrophobic nature of the PTFE between the ring and the disk might cause a decrease in the collection efficiency due to the partial retention of oxygen bubbles on the electrode as the oxygen generation current increased and the measurement time elapsed. This suggests that, unlike typical solution reactions, the dynamic determination of the oxygen gas collection efficiency is essential, considering current density and measurement time.Figure 2 illustrates the computation of faradaic oxygen efficiency, utilizing dynamic oxygen collection efficiency. The composite catalyst composed of TB and SCFOC was taken as an illustrative example. The variation in collection efficiency, synchronized with the shape of disk current density, was employed in determining the faradaic oxygen efficiency. This dynamic collection efficiency yielded a comparatively smooth faradaic oxygen efficiency.Utilizing the calibrated faradaic oxygen efficiency, we proceeded to assess the capacity of carbon degradation by integrating the current density of the carbon oxidation reaction (COR) calculated by subtracting the OER current from the overall current. As depicted in Figure 3, the COR capacity as a function of the potential suggested that the components of the composite catalysts had distinct impacts on carbon degradation. Specifically, SCFOC appears to enhance degradation, whereas LCO exhibits a comparatively less pronounced effect.A more comprehensive discussion of these findings will be presented at the upcoming meeting.[1] I.S. Filimonenkov et al., Electrochim. Acta 321, 134657 (2019).[2] Y. Miyahara et al., Chem. Mater. 32, 8195 (2020). Figure 1

Advancing Electrochemical Energy Storage: The Synergistic Impact of Sulfur Nano-Confinement in Hierarchically Porous Jute-Derived Activated Carbon for Enhanced Supercapacitor Performance

The availability of energy is a cornerstone for the modernization, automation, and economic growth of nations. With the rapid depletion of fossil fuels and rising environmental concerns, such as CO2 emissions leading to global warming, there has been an intensified search for alternative, renewable energy sources like solar and wind power. However, their intermittent nature necessitates robust electric energy storage systems for effectively harnessing these resources. Electrochemical energy storage devices, particularly batteries and supercapacitors, have emerged as a focal point of recent research due to their potential to bridge this gap. While supercapacitors are known for their high power density and long cycle life, they typically exhibit limited energy density. Recent advancements have shown that composites combining carbonaceous materials with redox-active nanomaterials can significantly enhance supercapacitors' electrochemical performance. In this context, our research explores the development of hierarchically porous activated carbon nanosheets (JAC) derived from jute, an abundantly available biomass. Using a straightforward pyrolysis process, we have investigated its potential in supercapacitor applications. The prepared JAC, when employed as an electrode material in a symmetric supercapacitor with a glycerol-based bio-electrolyte, demonstrated higher specific capacitance compared to its commercial counterparts. Further innovation was achieved through the introduction of sulfur doping in JAC (S-doped JAC). This novel approach leverages the inherent porous nanosheet morphology of JAC and heteroatom modification to yield exceptional electrochemical performance. Our findings reveal that the S-doped JAC composite, particularly the variant with 25% sublimed sulfur (SJAC-25), significantly outperforms the standard JAC in terms of specific capacitance (230 F/g vs. 130 F/g at 1.0 A/g current density) in a glycerol-KOH bio-based electrolyte. Moreover, a symmetric supercapacitor assembled with SJAC-25 showcased an impressive energy density of 32 Wh/kg at a power density of 500 W/kg, maintaining 28 Wh/kg even at a heightened power density of 2500 W/kg. This demonstrates its capability to retain high energy efficiency under varying power conditions. Additionally, the SJAC-25 based supercapacitor exhibited remarkable durability, with about 94% capacitance retention and 86% Coulombic efficiency after 10,000 charge-discharge cycles. Our research not only highlights the potential of processed bio-waste as a viable material for energy storage but also introduces an advanced, scalable, and straightforward synthesis method. This method could pave the way for the preparation of highly porous and sulfur-doped nanoporous carbon, setting a new benchmark for high-performance electrochemical energy storage applications.

Enhancing charge storage capacity of cellulose-sweat-based electrolyte flexible supercapacitors with electrochemically exfoliated free-standing carbon yarn electrodes

The Internet of Things (IoT) provides an interface between different electronic devices such as flexible electronics, and e-textiles to capture and receive real-time data and help humans to devise systems that will adequately respond to these environmental stimuli. The main limitations of these devices to work 24/7 are the lack of continuous power supply and easy integration into textiles to perform their functions. The other issues are poor adhesion of active materials with substrates and peeling-off of active material from the electrode substrates and consequently, degradation of electrochemical performance. A potential and evolving strategy is fabricating a current collector-less and integrable carbon yarn-based energy storage device. Herein, we are presenting a facile and novel technique to exfoliate carbon yarn fibers to enhance their electrochemical performance by 3 orders of magnitude. Activated carbon yarn wires acting as current collector-less electrodes along with cellulose acetate-based composite separators offer a large surface area to simulated sweat electrolyte ions and show a gravimetric capacitance of 11.28 Fg−1 at the scan rate of 5 mVs−1. Activated carbon yarn-based symmetric supercapacitor device in a simulated sweat solution electrolyte offers excellent cyclic and bending stability with over 95 % capacitance retention in both tests. Theoretical insightSupercapacitors (SCs) comprise many active and passive elements. The most passive and vital elements are current collectors, separators, binders, electrolytes, and packaging. Two key elements, current collector and binders can be eliminated by developing current collector-free or free-standing electrodes. Carbonaceous materials such as graphene [1,2], carbon nanotubes (CNT) [3], porous carbon [2], and carbon onions[4,5] are common alternatives of active materials for SCs electrodes owing to their low cost, chemical stability, large surface area, and high electrical conductivity. These active materials show exceptional attributes such as long cyclic life, and high-rate capability owing to their intrinsic operation mechanism e.g., surface charge storage due to large surface area. However, they also suffer from low specific capacitance ascribed to low surface area exposed to electrolyte ions and low charge storage due to poor wettability. The most efficient technique to address this problem is to incorporate doped heteroatoms or surface functional groups such as surface oxygen groups present on the surface of carbon yarn. The inclusion of these doped heteroatoms and functional groups boosts the intrinsic properties, such as electrical conductivity, and wettability. The increased electro-active surface area offers more active sites for electrolyte ions, resulting in more charge storage and higher pseudocapacitance [6–8].Carbon yarn comprised of long-chain carbon filaments of 2.5–5 µm in radius, excellent conductivity, high chemical and mechanical stability, and light weightiness make it a potential candidate as an active material or a free-standing electrode for SCs. However, due to its low specific capacitance, limited surface area, and low porosity, carbon yarn failed to be directly exploited as a free-standing or current collector-less electrode for flexible supercapacitor applications.

The effect of carbon coating on the arsenite sorption by magnetic carbon nanocomposites

AbstractArsenic pollution has emerged through anthropogenic activities and natural mineral leaching processes. This study aims to advance the use of magnetic carbon nanocomposites (MCNs) in the sorption of arsenic, studying the influence of feedstock and the presence of carbon coating on magnetic nanoparticles. Previous works have shown that post-pyrolysis treatment improves the stability of MCNs by reducing iron leaching due to the formation of a carbon coating that encapsulates the iron oxide nanoparticles. However, this carbon coating could influence the adsorption properties of MCNs. This investigation deals with arsenic adsorption by four MCNs prepared by co-precipitation of magnetite (Fe3O4) nanoparticle into four carbonaceous matrixes, followed by a post-pyrolysis treatment. The pristine carbonaceous matrixes used in the present work were commercial activated carbon (CAC), charcoal (CC), hydrochar from the orange residue (HCOR), and biochar from sunflower husk (BCSFH). Pristine carbonaceous materials and MCNs without post-pyrolyzed were also used as arsenic sorbents in water solutions. Additionally, kinetic studies were carried out to explore the sorption properties of different MCNs and pristine materials, concerning the removal efficiencies (expressed as a percentage) and adsorption capacities, determining the equilibrium time. The results demonstrated that the presence of magnetite increases the adsorption of arsenic, being higher in the case of materials obtained by direct co-precipitation than in materials subjected to a post-pyrolysis process. The presence of a carbon layerprotecting the magnetite slightly decreases the adsorption of arsenic.

Renewable Musa Sapientum derived porous nano spheres for efficient energy storage devices

Biomass-based carbonaceous materials derived from Musa Sapientum have gained much attention in recent years for their application in energy storage devices, especially supercapacitors. In the present work, we synthesized carbonaceous material from banana peel as the biomass precursor by using a pyrolysis method carried out at various temperatures (600, 800, and 1000 °C). The characterization of the prepared carbonaceous materials BP600, BP800 and BP1000 was done by using different characterization techniques such as FTIR, XRD, FE-SEM, and TEM, studies. The electrochemical study of the synthesized material was carried out by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) electrochemical impedance spectroscopy (EIS). The supercapacitive performance of the material was studied using a 3-electrode system with 3M KOH as an electrolyte. As a result, the BP600 exhibited a better specific capacitance with higher energy and power densities along with a maximum cyclic stability of 16,000 cycles. To show the practical applicability of the material BP 600, two electrode system studies were carried out as well, which showed preferentially good values for specific capacitance with appreciable power and energy density values. The study provides us with a green approach for the fabrication of non-toxic, low-cost, and environmentally friendly potential porous carbonaceous electrode materials by converting bio-waste into a clean and renewable source of energy.

Adsorption of Cobalt onto Zeolitic and Carbonaceous Materials: A Review

Adsorption of Cobalt onto Zeolitic and Carbonaceous Materials: A Review

Surface properties of activated carbon fibers obtained from polyacrylonitrile and methyl acrylate: Experimental and simulation studies for lead and acid blue 25 dye adsorption from water

Activated carbon fibers were prepared using a methyl acrylate/polyacrylonitrile (MA/PAN) system and H3PO4 activation. These fibers were assessed to adsorb AB25 and Pb2+ from aqueous solutions, and DFT calculations were carried out to determine the main surface interactions that caused the removal of both pollutants. The results showed that AB25 and Pb2+ adsorption on these activated carbon fibers was endothermic, with maximum experimental adsorption capacities of 0.012 − 0.023 and 0.248 − 0.306 mmol/g at 20 – 40 °C. Pb2+ adsorption properties of these fibers outperformed those of other carbonaceous materials utilized in the depollution of metallic cations, whereas their removal effectiveness was less competitive to separate AB25 dye molecules. A double-site monolayer model was applied to correlate the experimental Pb2+ isotherms, while AB25 adsorption on activated carbon fibers was simulated using a one-site multilayer model. Oxygenated acidic (i.e., carboxylic and phenolic) and phosphate-carbon functional groups were the main binding sites to adsorb these pollutants. The adsorption energies of the tested systems, the identification of the most feasible binding positions of the tested adsorbates on the activated carbon fiber surface, and the role of hydrogen bonding in the corresponding adsorption mechanisms were discussed using DFT calculations. These results contribute to the valorization and application of engineered materials such as activated carbon fibers for water depollution.

Flexible Strain Sensors Based on Thermoplastic Polyurethane Fabricated by Electrospinning: A Review.

Over recent years, thermoplastic polyurethane (TPU) has been widely used as a substrate material for flexible strain sensors due to its remarkable mechanical flexibility and the ease of combining various conductive materials by electrospinning. Many research advances have been made in the preparation of flexible strain sensors with better ductility, higher sensitivity, and wider sensing range by using TPU in combination with various conductive materials through electrospinning. However, there is a lack of reviews that provide a systematic and comprehensive summary and outlook of recent research advances in this area. In this review paper, the working principles of strain sensors and electrospinning technology are initially described. Subsequently, recent advances in strain sensors based on electrospun TPU are tracked and discussed, with a focus on the incorporation of various conductive fillers such as carbonaceous materials, MXene, metallic materials, and conductive polymers. Moreover, the wide range of applications of electrospun TPU flexible strain sensors is thoroughly discussed. Finally, the future prospects and challenges of electrospun TPU flexible strain sensors in various fields are pointed out.

Solid carbonaceous materials transformation during pulverised coal and natural gas co-injection

Co-injection of coal and gaseous fuel, such as natural gas (NG), is common practice promoting pulverised coal gasification in blast furnace (BF) ironmaking. The high hydrogen content in NG makes it possible to act as cleaner reductant to reduce iron ore to produce hot metal, which will result in reduced CO2 emissions during the ironmaking process. In this work, selected parameters affecting the overall performance of the pulverised coal and natural gas co-injection system were studied using the CanmetENERGY injection test rig, including coal injection rate, natural gas rate and blast oxygen enrichment. Increase in combustion intensity promotes conversion of injected coal into solid carbonaceous material with relatively low reactivity with CO2. Hence, it reduces the competitiveness of combustion residues for oxygen in the raceway to continue the gasification process. NG co-injection reduces the coal combustion intensity but enhances the reactivity of combustion residues by competing the oxygen in the raceway.

Investigation of column purified dye derived carbon nanomaterials for security printing and supercapacitor applications

Literature evidence reveals versatile applications of carbon dots (CDs), but generally mixtures of various types of carbon nanomaterials, molecular intermediates as well as side products are obtained upon hydrothermal treatment of the precursor material. This demands isolation of pure components and their complete characterization before these nano carbonaceous materials are chosen for suitable applications. In the present study, perylenetetracarboxylic dianhydride (PTCDA) is subjected to hydrothermal treatment and the mother liquor obtained is separated using column chromatography technique using dichloromethane-methanol solvent system to isolate fractions of various fluorescent carbonaceous nanostructures. The TEM imaging of nano carbonaceous particles of all five fractions indicated that the first and third fractions were composed of nanoribbons, while the latter two fractions largely contained quasi-spherical nanoparticles of both lesser (carbon quantum dots) and greater (carbon nanodots) than 10 nm dimensions. The XPS results of all the fractions suggested separation based on polarity difference. The ID/IG ratios obtained from Raman spectra implied the presence of several defects on the CDs. The time resolved fluorescence spectra of third, fourth and fifth fractions revealed mono-exponential decay of fluorophores with excitation independent average lifetime values. The fifth fraction exhibited good biocompatibility and the highest absolute fluorescence quantum yield of 58.47 % among all the isolated samples. As these CDs displayed a remarkable rise in the quantum yield to 88.60 % when dispersed in water, a water-based flexo-ink was formulated. The photostable pale yellow flexo print proofs obtained on UV dull paper exhibited a green fluorescence under 365 nm illumination, whereas a yellow glow when shined with blue light, which can serve as an authentication feature for security documents and currency notes. Moreover, as the third fraction constitutes mainly of carbon nanoribbons (CNRs), an optimized polymer electrolyte was prepared along with sodium alginate (SA), and MgCl2 to understand their potential use in energy storage application. A supercapacitor was fabricated and tested for its electrochemical performance such as cyclic voltammtery (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCD). An enhanced current window was observed in the CV of SA/CNRs compared to pure SA and SA/CNRs/Mg films, which indicated a structural interaction of CNRs with SA. The conductivity of SA/CNRs/Mg was lesser than SA/CNRs in EIS studies due to the presence of Mg ions, while pure SA showed lesser conductivity. The dual ionic interaction of Na and Mg along with enhanced structural stability due to doped CNRs favors its convenient supercapacitor application. The fabricated eco-friendly supercapacitor showed a specific capacitance of 84 F/g. The GCD of the device displayed pseudocapacitance behaviour and was quite stable for 2000 cycles with coulombic efficiency of 96 %.

Biomass‐Derived Porous Carbon Materials for Electrocatalysis

AbstractResearch of electrocatalysts based on biomass derived porous carbon materials become one of promising strategies to boost the development of carbon cycle and energy storage technologies. As substitutes for precious metals in electrocatalysis, many biomass derived porous carbon materials exhibit excellent chemical stability, interface chemical inertness, strong structural mechanical strength and high conductivity. However, significant efforts are still needed to develop environmentally friendly, scalable and low‐cost synthetic methods to provide biomass‐derived carbonaceous materials with electrocatalytic performance that is comparable to, or even surpasses, that of existing precious metal catalysts. In this mini‐review, the main synthesis methods, electrocatalytic performances and working principle of biomass derived porous carbon materials have been summarized and discussed. The perspectives of doping strategy for these electrocatalyst candidates have been emphasized in the discussion.