Hierarchical nanoarchitecture of vanadium disulfide decorated 3D porous carbon skeleton with improved electrochemical performance toward Li ion battery and supercapacitor

Vanadium disulfide (VS₂) is deemed to be a competitive active material in electrochemical energy storage field in both lithium-ion battery and supercapacitor owing to its unique chemical and physical property. Nevertheless, serious aggregation and structure damage in continuous charge-discharges would result in a decreased capacity, an inferior cycling stability and a poor rate capability, which severly limits the practical application of VS₂. In this current work, a hierarchical porous nanostructured composite composed of VS₂ nanoparticles confined in gelatin-derived nitrogen-doped carbon network (VS₂-NC) was successfully designed and synthesized via a simple freeze drying plus an annealing method. In this VS₂-NC composite, porous architecture is conductive to providing high active surface areas, facilitating the access of electrolyte into active materials and ion diffusion. The confinement of carbon matrix on VS₂ nanoparticles is beneficial to inhibition of the volume change, reinforcement of the structural stability and improvement of the overall electrical conductivity of composite. Benefitting from the advantages mentioned above, the as-prepared VS₂-NC electrode demonstrates outstanding electrochemical performances. Employed as an anode for lithium ion battery, VS₂-NC delivers a relatively high reversible capacity about ～1061 mA h g^?1 in 200-cycle test at 100 mA g^?1. When applied in supercapacitor, VS₂-NC electrode manifests a large pseudocapacitance of 407.3 F g^?1 at a current density of 10 A g^?1 and superior cycling stability.     

Ultra-high specific capacitance of self-doped 3D hierarchical porous turtle shell-derived activated carbon for high-performance supercapacitors

The turtle shell of biomass waste is used as raw material, and the natural inorganic salt contained in it is used as a salt template in combination with a chemical activation method to successfully prepare a high-performance activated carbon with hierarchical porous structure. The role of hydroxyapatite (HAP) and KOH in different stages of preparation was investigated. The prepared turtle shell-derived activated carbon (TSHC-5) has a well-developed honeycomb pore structure, which gives it a high specific surface area (SSA) of 2828 m² g^?1 with a pore volume of 1.91 cm³ g^?1. The excellent hierarchical porous structure and high heteroatom content (O 6.88%, N 5.64%) allow it to have an ultra-high specific capacitance of 727.9 F g^?1 at 0.5 A g^?1 with 92.27% of capacitance retention even after 10,000 cycles. Excitingly, the symmetric supercapacitor assembled from TSHC-5 activated carbon exhibits excellent energy density and cycling stability in a 1 M Na₂SO₄ aqueous solution. The energy density is 45.1 Wh·kg^?1 at a power density of 450 W kg^?1, with 92.05% capacitance retention after 10,000 cycles. Therefore, turtle shell-derived activated carbon is extremely competitive in sustainable new green supercapacitor electrode materials.     

Electrochemical behavior of CuO/rGO nanopellets for flexible supercapacitor,non-enzymatic glucose,and H2O2 sensing application

In the present article, graphene oxide (GO) sheets and monoclinic copper oxide (CuO) nanocrystals are connected with each other and result in the formation of CuO/rGO nanopellets, and these nanopellets synthesized using coprecipitation method. The nanopellet structured CuO/rGO composite on carbon cloth, which act as current collector exhibits specific capacitance of 188 F g^?1 at a current density of 0.2 A g^?1 and up to 96.3% capacity retention after 2000 charge-discharge cycles. It shows a maximum energy density of 7.32 Wh kg^?1 and power density of 53 W kg^?1. The glucose sensing characteristics of CuO/rGO nanopellet is investigated on carbon cloth and ITO substrate. It shows glucose sensitivity of 0.805 mA mM^?1 cm^?2 and 0.2982 mA mM^?1 cm^?2 for a bundle like structured CuO/rGO composite on carbon cloth and ITO substrate, respectively. Further H₂O₂ sensing is studied on ITO substrate, which manifests H₂O₂ sensitivity of 84.39 μA mM^?1 cm^?2. The results indicate that nanopellet structured CuO/rGO composite could be a promising electrode material for supercapacitor, glucose, and H₂O₂ sensor.     

Nanowires embedded porous TiO2@C nanocomposite anodes for enhanced stable lithium and sodium ion battery performance

A porous carbon nanocomposite with embedded TiO₂ nanowires (NWs) was synthesized using a two-step synthetic method in which carbon matrix was obtained by carbonizing a vacuum dried gel. This unique structure in which TiO₂ nanowires uniformly distributed in and tightly bonded to the carbon matrix shortened the electron transport path and reduced the transmission resistance. Nanoporous structure ensured continuous transfer of Li⁺/Na⁺ and supplied a large specific surface area of 280.82 m² g⁻¹ to provide more active sites. Different from other existing works on TiO₂@C anode materials with TiO₂ loading higher than 60 wt%, the obtained very small amount of TiO₂ (~12 wt%) improved the electrochemical and long-cycle performance of carbon substrate with TiO₂ NWs embedded significantly, due to uniformly distributed TiO₂ NWs throughout the carbon matrix. These TiO₂@C composite anodes could deliver a specific capacity of 286 mA h g⁻¹ at 0.3 C, 197 mA h g⁻¹ at 0.15 C for lithium and sodium ion batteries, respectively. It maintained remarkably stable reversible capacities of 128 and 125 mA h g⁻¹ for lithium and sodium ion batteries at 3 C during 2500 cycles, respectively. Smaller fluctuations and smoother curves demonstrated that sodium ion storage was more stable than lithium ion storage for the TiO₂@C composite anode. In addition, the capacitive contributions of TiO₂@C in both systems are quantified by kinetics analysis.     

Encapsulating homogenous ultra-fine SnO2/TiO2 particles into carbon nanofibers through electrospinning as high-performance anodes for lithium-ion batteries

Homogenous ultra-fine SnO₂/TiO₂ particles encapsulated into carbon nanofibers (SnO₂/TiO₂@CNFs) with a uniform and ordered one-dimensional fibrous structure are fabricated through facile electrospinning technique and subsequent heat treatments, which are confirmed by XRD, Raman, TG, SEM, TEM, and XPS analyses. The battery performance reveals that the SnO₂/TiO₂@CNFs-1.5:1 (1.5:1 denotes the mole ratio of SnO₂ to TiO₂ in the carbon nanofibers) electrode displays the optimal electrochemical properties among the whole samples, which can deliver the initial charge and discharge specific capacity of 1061.2 and 1494.8 mAh/g with a coulombic efficiency of 71.0% at 100 mA/g, and exhibit a remarkable specific capacity of 766.1 mAh/g after 200 cycles. Moreover, the SnO₂/TiO₂@CNFs-1.5:1 electrode displays a high pseudocapacitive contribution of 73.9% at the scan rate of 2 mV/s and the lithium ion diffusion coefficient of approximately 1.20 × 10^?15 cm² s^?1. The excellent electrochemical performance of the SnO₂/TiO₂@CNFs-1.5:1 electrode is closely correlated with the synergetic effect of the proper amount of TiO₂ that enhances the electrochemical stability of the electrode and provides fractional capacity, and the flexible and conductive carbon nanofiber matrix that accommodates volume changes and increases overall electronic conductivity. The detailed investigations of the as-prepared electrode materials by a facile electrospinning process may pave possible instructions for the next generation SnO₂-based anodes and other related electrospun anodes for the energy storage device.     

A new strategy for porous carbon synthesis: Starch hydrogel as a carbon source for Co3O4@C supercapacitor electrodes

A novel Co₃O₄@C composite with a three-dimensional (3D) interconnected network morphology was successfully fabricated by anchoring cobalt oxide nanocrystals onto porous carbon originating from starch hydrogels via freeze drying, precarbonization and thermal treatment in an aqueous system. Benefiting from unique structural features, the optimized electrode delivers an excellent capacitance of 1314.0 F g^?1 (1 A g^?1) and outstanding durability in terms of capacity preservation (93.5% over 10,000 cycles). In addition, an asymmetric supercapacitor consisting of DF-2 and active carbon exhibits an energy density of 149.1 Wh?kg^?1 at 800 W kg^?1 while maintaining great stability. The observed excellent performance is attributed to the unique 3D network, good conductivity and high surface-to-volumetric ratio of the carbon skeleton derived from the starch gel, which has wide scope for applications.     

Sucrose derived microporous–mesoporous carbon for advanced lithium–sulfur batteries

A microporous–mesoporous carbon has been successfully prepared via carbonization of sucrose followed by heat treatment process. The obtained porous carbon possesses abundant micropores and mesopores, which can effectively increase the sulfur loading. The composite exhibited a remarkable initial capacity of 1185 mAh g^?1 at 0.2 A g^?1 and maintained at 488 mAh g^?1 after 200 cycles, when employed for lithium?sulfur batteries. Moreover, the composite displayed enhanced rate capabilities of 1124, 914 and 572 mAh g^?1 at 0.2, 0.5 and 1.0 A g^?1. The outstanding electrochemical capabilities and facile low?cost preparation make the new microporous–mesoporous carbon as an excellent candidate for lithium sulfur batteries.     

Improving water desalination performance of electrospun carbon nanofibers by supporting with binary metallic carbide nanoparticles

Capacitive deionization (CDI) technology is proposed as an environmentally friendly way to desalinate brackish water samples with outstanding efficiency. Since the nanomaterial composition is the controlling factor in the measured activity of fabricated CDI cells, much efforts are directed to explore highly effective nanocomposites with increased electrosorptive capacity and enhanced regeneration behavior during operation for longer periods. Here, the electrospinning process was devoted to synthesize mixed cobalt and titanium carbides nanoparticles onto carbon nanofibers [Co–TiC@CNFs] using cobalt acetate tetrahydrate (CoAc) and titanium (IV) isopropoxide (TIP) as precursor salts and polyvinylpyrrolidone (PVP) as a carbon source. Electrospun mats were then calcined at 950 °C for 6 h using a tube furnace with passing argon gas. This formed nanoporous material could provide numerous pathways for increased ions adsorption with extraordinary electrical conductivity. This could explain its enhanced electrochemical properties as evidenced by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy (EIS) methods. A specific capacitance value of 979.40 F g^?1 was estimated for Co–TiC@CNFs as 7.42 times higher than that for bare CNFs. Furthermore, this nanohybrid material had a salt adsorption capacity of 33.10 mg g^?1 in 1.0 M NaCl solution at 1.2 V that highly exceeded the obtained ones for TiC [2.20 mg g^?1] and CNFs [8.20 mg g^?1]. Accordingly, modifying carbon nanofibers with metallic carbides can create suitable nano-constituents for promising CDI cell output.     

Efficient fabrication of carbon/silicon carbide composite for electromagnetic interference shielding applications

Ceramic matrix composites are typically prepared by a costly, time-consuming process under severe conditions. Herein, a cost-effective C/SiC composite was fabricated from a silicon gel-derived source by Joule heating. The β-SiC phase was generated via carbothermal reduction, and the carbon fabric showed a well-developed graphitic structure, promoting its thermal and anti-oxidation stabilities. Owing to the excellent dielectric loss in carbon fabric, SiC and SiO₂ as well as the micropore structure of the ceramic matrix, the absolute electromagnetic interference shielding (EMI) effectiveness (SSE/t) reached 948.18 dB?cm²?g^-1 in the X-band, exhibiting an excellent EMI SE. After oxidation at 1000 °C for 10 h in the air, the SSE/t of the composite was only reduced to 846.02 dB?cm²?g^-1. The C/SiC composite promises the efficient fabrication of high-temperature resistant materials for electromagnetic shielding applications.     

Enhanced thermal shrinkage behavior of phenolic-derived carbon aerogel-reinforced by HNTs with superior compressive strength performance

A novel carbon/m-HNTs composite aerogel was synthesized by introducing the modified halloysite nanotubes (m-HNTs) into phenolic (PR) aerogels through chemical grafting, followed with carbonization treatment. In order to explore the best proportion of HNTs to phenolic, the micromorphology of PR/m-HNTs were investigated by SEM before carbonization, confirming 10 wt% of m-HNTs is most beneficial to the porous network of aerogels. The interaction between PR and HNTs was studied by FTIR spectra, and microstructure evolution of the target product-carbon/m-HNTs composite aerogel were illustrated by SEM and TEM techniques. SEM patterns indicated that the carbon/m-HNTs aerogels maintain a stable porous structure at 1000 °C (carbonization temperature), while a ~20 nm carbon layer was formed around m-HNTs generating an integral unit through TEM analysis. Specific surface area and pore size distribution of composite aerogels were analyzed based on mercury intrusion porosimetry and N₂ adsorption–desorption method, the obtained results stayed around 500 m²g^?1 and 1.00 cm³g^?1 (pore volume) without significant discrepancy, compared with pure aerogel, showing the uniformity of pore size. The weight loss rate (26.76%) decreased greatly compared with pure aerogel, at the same time, the best volumetric shrinkage rate was only 30.83%, contributed by the existence of HNTs supporting the neighbor structure to avoid over-shrinking. The highest compressive strength reached to 4.43 MPa, while the data of pure aerogel was only 1.52 MPa, demonstrating the excellent mechanical property of carbon/m-HNTs aerogels.     

NiSe2 encapsulated in N-doped TiN/carbon nanoparticles intertwined with CNTs for enhanced Na-ion storage by pseudocapacitance

Transitional metal selenides are considered as potential anode candidates for sodium-ion batteries (SIBs) because of their relatively high theoretical capacity and environmental benign. However, the large volume change derived from the conversion reaction and the sluggish kinetics due to the inherent low electrochemical conductivity hinder their practical application. Herein, composite materials of NiSe₂ encapsulated in nitrogen-doped TiN/carbon nanoparticles with carbon nanotubes (CNTs) on the surface (NiSe₂@N-TCP/CNTs) are fabricated via pyrolysis and selenization processes. In this composite, TiN inside the carbon matrix can enhance the conductivity and structural stability. CNTs that are in-situ grown on the surface not only further enhance the conductivity of the composites, but also offer sufficient space to buffer the volume expansion and alleviate serious aggregation of NiSe₂ nanoparticles. Benefit from these merits, the NiSe₂@N-TCP/CNTs showed a lower charge transfer resistance and a faster Na⁺ diffusion rate than materials without growing CNTs. When used as the anode of SIBs, the NiSe₂@N-TCP/CNTs electrode delivered a reversible capacity of 344.0 mAh g^?1 after 1000 cycles at 0.2 A g^?1, and still maintained at 272.7 mAh g^?1 even at a high current density of 2 A g^?1. The remarkable electrochemical performance is mainly attributed to the special designed hierarchical structures and pseudocapacitance sodium storage behavior.     

Hierarchically Fe-doped porous carbon derived from phenolic resin for high performance supercapacitor

Supercapacitors are promising for high power application in the recent years. In particular, the conversion of simple and available carbon materials into economic and high performance electrical devices receives excellent scientific and technological interest. This paper reports a one-step strategy for synthesizing hierarchical porous carbon derived from phenolic resin (PR), which is then used to configure electric double-layer capacitors (EDLCs). Here, a carbon material with a flexible porous structure, large specific surface area, and high graphitization degree is prepared using potassium ferrate (K₂FeO₄) to catalytically activate PR and to realize synchronous carbonization and graphitization. This method overcomes the disadvantage of time-consuming, high-cost, and environmentally unfriendly. In addition, the as-prepared carbon material has a high specific surface area (1086 m² g^?1) and a large pore size (3.07 nm), which can increase the transfer rate of electrolyte ions. The specific capacitance of the obtained electrode material is 315 F g^?1 at 1.0 A g^?1, and the optimized electrode material has an ultra-long cycle lifetime (capacitance retention rate is 96.3% after 10,000 cycles). Thus, the hierarchically Fe-doped porous carbon material derived from PR material is expected to realize high rate capacitance for supercapacitor applications.     

Carbon coated porous tin peroxide/carbon composite electrode for lithium-ion batteries with excellent electrochemical properties

A porous tin peroxide/carbon (SnO₂/C) composite electrode coated with an amorphous carbon layer is prepared using a facile method. In this electrode, spherical graphite particles act as supporter of electrode framework, and the interspace among particles is filled with porous amorphous carbon derived from decomposition of polyvinylidene fluoride and polyacrylonitrile. SnO₂ nanoparticles are uniformly embedded in the porous amorphous carbon matrix. The pores in amorphous carbon matrix are able to buffer the huge volume expansion of SnO₂ during charge/discharge cycling, and the carbon framework can prevent the SnO₂ particles from pulverization and re-aggregation. The carbon coating layer on the outermost surface of electrode can further prevent porous SnO₂/C electrode from contacting with electrolyte directly. As a result, the repeated formation of solid electrolyte interface is avoided and the cycling stability of electrode is improved. The obtained SnO₂/C electrode presents an initial coulombic efficiency of 77.3% and a reversible capacity of 742 mA h g⁻¹ after 130 cycles at a current density of 100 mA g⁻¹. Furthermore, a reversible capacity of 679 mA h g⁻¹ is obtained at 1 A g⁻¹.     

Ordered mesoporous carbon–TiO2 materials for improved electrochemical performance of lithium ion battery

A series of ordered mesoporous carbon–TiO₂ (OMCT) materials with various weight percentages of TiO₂ (50–75 wt%) were synthesized by evaporation-induced self-assembly and in-situ crystallization at various calcination temperatures (600–1200 °C) to evaluate the Li-ion storage performance. The OMCT has ordered 2D hexagonal mesoporous structures and the TiO₂ nanocrystals with different phases are embedded into the frameworks of carbonaceous matrix. The reversible capacity of OMCT is highly dependent on the phase and content of TiO₂, and the anatase TiO₂ is a superior crystalline phase to rutile and TiN for Li-ion insertion. The OMCT₆₅ which contains 35 wt% carbon and 65 wt% TiO₂ shows a high capacity of 500 mAh g^?1 at 0.1C after 80 cycles. In addition, OMCT₆₅ exhibits a good cyclability and rate capability. The reversible capacity remains at 98 mAh g^?1 at a high rate of 5C, and then recoveries to 520 mAh g^?1 at 0.1C after 105 cycles. The excellent reversible capacity and rate capability of OMCT₆₅ are attributed to the embedment of well-dispersed anatase TiO₂ nanocrystals into the specific porous structure of OMCT, which can not only facilitate the fast Li-ion charge transport but can also strengthen the carbon–TiO₂ co-constructing channels for lithiated reactions.     

Preparation and molten salt-assisted KOH activation of porous carbon nanofibers for use as supercapacitor electrodes

Carbon nanofiber paper was prepared by electrospinning from thermosetting phenolic resin, followed by activation via KOH-containing molten salt at high temperature. By adding a small dosage of KOH in the molten salt the porous volume and specific surface area could be greatly improved. The obtained porous carbon nanofibers had a specific surface area of 1007 m² g^?1, total pore volume of 0.363 cm³ g^?1, micropore volume of 0.247 cm³ g^?1. The electrochemical measurements in 6 M KOH aqueous solution showed that the porous carbon nanofibers possessed high specific capacitance and considerable rate performance. The maximal specific capacitance of 288 F g^?1 was achieved at 0.2 A g^?1 and the specific capacitance could still remain 204 F g^??1 at 20 A g^?1 with the retention of 71%. In the molten salt system, the reaction between activating agent and carbon could be more efficient, hence, such molten salt-assisted activation method was considered as a general activation method for the high-specific-surface-areaed carbons.     

Ultrathin N‐doped carbon‐coated TiO2 coaxial nanofibers as anodes for lithium ion batteries

The structural optimization of TiO₂ materials has a significance for improving the electrochemical performance since TiO₂ suffers from poor electronic conductivity. For this purpose, ultrathin N‐doped carbon‐coated TiO₂ coaxial nanofibers have been designed and synthesized by a facile electrospinning approach. Microstructure analysis indicates that the TiO₂ nanofibers can be coated by the ultrathin carbon layers. Electrochemical tests reveal that the rate performance and cycling ability of TiO₂@C nanofibers have been enhanced obviously. The TiO₂@C6 nanofibers carbonized at 600°C exhibit superior features with a specific discharge capacity of 284 mAh g^?1 at a current density of 100 mA g^?1 after 100 cycles. Besides improved rate performance of 117 mAh g^?1 at a high current density of 2000 mA g^?1 and excellent cycling stability with only about 0.008% capacity loss per cycle were also obtained in the sample TiO₂@C6 after 500 cycles at the current density of 1000 mA g^?1. Such remarkable performance may be ascribed to the unique one‐dimensional nanofibers as flexible carbon matrix.     

Superior electrocatalytic ORR performance of Melaleuca Leucadendron L barks derived hierarchical porous carbon with abundant atom-scale vacancies and multiheteroatoms

Biomass feedstocks from agriculture and forestry usually possess unique isometric microstructures that are used as potential renewable precursors to synthesize hierarchically porous carbon materials for energy-conversion applications. Herein, the powders of Melaleuca leucadendron L. barks (MLBs) impregnated with a hydrogen bonded complex (HBC) were carbonized to prepare CoBN-doped porous carbon (CBNC) as oxygen reduction reaction (ORR) electrocatalysts. The microstructure, porous texture and compositions of the as-obtained CBNC samples and their intermediates were characterized by small-angle neutron scattering (SANS) and other techniques. The lamellar structure of MLBs and the HBC strategy endowed the as-obtained CBNC with a unique porous texture, large specific surface area (1041 m² g^?1) and uniformly distributed heteroatoms of Co, B and N. The introduction of Co species in the precures is beneficial to improving the formation of atomic defects. The CBNC sample obtained at the optimized conditions exhibited a half-wave potential (E_1/2) of 0.83 V and a kinetic current density (j_k) of 9.73 mA cm^?2 as well as a robust durability and methanol tolerance in the alkaline electrolyte; its overall ORR properties were highly superior to Pt/C (j_k = 8.2 mA cm^?2, E_1/2 = 0.82 V). This novel approach offers a feasible way towards producing high-performance ORR electrocatalysts from biomass wastes.     

An effective and simple way to synthesize LiFePO4/C composite

The cathode material is synthesized from FeC₂O₄·2H₂O and LiH₂PO₄ by a solid-state reaction using citric acid as a carbon source. The electric conductivity of the synthesized LiFePO₄ has been raised by eight orders of magnitude from 10⁻⁹ S cm⁻¹. The LiFePO₄/C composite shows a greatly enhanced rate performance and the cyclic stability at room temperature. It delivers an initial discharge capacity of 128 mAh g⁻¹ at 4C, which is retained as high as 92% after 1000 cycles. In addition, the tested low temperature character is attractive. At −20 °C, the composite exhibits a discharge capacity of 110 mAh g⁻¹ at 0.1C. The homogenous morphology, the porous surface, the small particles inside and the conductive carbon observed contribute much to obtain the favorable electrochemical performance.     

Mixed fuel approach for the fabrication of TiO2:Ce3+ (1–9 mol%) nanophosphors: Applications towards wLED and latent finger print detection

TiO₂:Ce³⁺ (1–9?mol%) nanophosphors (NPs) were prepared by solution combustion method using combination of fuels. PXRD studies of pure and doped samples exhibit rutile and anatase phases respectively. SEM results indicate that the particles were found to be nearly spherical in nature. The energy band gap (E_g) of pure and doped samples was found to be in the range 3.10–3.23?eV. The active vibrational Raman modes observed at ～ 141, 446 and 608?cm^?1 were corresponds to B_1g, E_g and A_1g respectively. The mode at ～ 229?cm^?1 was due to second order effect that confirms the rutile phase of TiO₂. The CIE and CCT results of the doped TiO₂ shows that this product exhibits green colour (CIE-coordinates x = 0.3649, y = 0.4023) and was suitable for wLEDs which can be used for household applications. The optimized product was further utilized for the visualization of latent finger prints (LFPs) on various porous and non- porous surfaces. The results reveal that, all the levels (I–III) of ridge feature were clearly visualized under normal light indicating that the powder was a reliable and promising labeling agent for LFPs detection as well as wLED applications.     

Synthesis and dye separation performance of ferromagnetic hierarchical porous carbon

Ferromagnetic hierarchical porous carbon (FHPC) with nickel particles embedded in the hierarchical porous carbon skeleton was synthesized. The hierarchical macro–mesoporous skeleton was formed by dissolving a salt template of Na₂CO₃ and the ferromagnetic nickel particles were produced by in situ carbothermal reduction of nickel oxide. The saturation magnetization, remnant magnetization and coercive force of FHPC are 11.3 emu g⁻¹, 2.3 emu g⁻¹ and 55.7 Oe. The ferromagnetic property enables the magnetic separation of the FHPC from water. The surface chemical environments of the FHPC consist of different oxygen functional groups, like –OH, >COO and >CO groups, as well as a trace amount of aliphatic species of –CH₃ or -CH_2^- structures. Dye separation performance of the FHPC was investigated using methylene orange, and the adsorption capacity was 0.16 mg m⁻² with the adsorption kinetics constant of 2.2 m² mg⁻¹ min⁻¹, which is superior to that of magnetic carbon spheres.