Rich Micropores Research Articles

Hollow carbon nanofibers with self-induced internal electric field for high-performance full-carbon sodium ion capacitors

Self-induced internal electric field (SIEF) is crucial to achieve high capacity, high rate and long cycle life of carbon anodes in Na+ storage, but it is also a huge challenge currently. Herein, a template-assisted electrospinning process and subsequent low-temperature pyrolysis method is employed to synthesize S, N co-doped hollow carbon nanofibers (SNHCF) with rich micropores and chemisorption sites. The rich micropores and interconnected macroporous in SNHCF provide large internal availability that effectively exposing the active sites, inhibiting the volume expansion and shortening the Na+ diffusion distance. Besides, S, N co-doping in the carbon skeleton can act as an electron acceptor and electron donor respectively to form a SIEF to boost adsorption of Na+. Theoretical calculation and ex-situ characterizations confirmed that S, N co-doping can regulate the electronic configuration and reduce the diffusion barrier of Na+. As a result, SNHCF anode has ultra-high specific capacity (588.2mAh g−1 at 0.05 A/g) and impressive rate performance (264.3mAh g−1 at 20 A/g). The full-carbon sodium ion capacitors assembled with SNHCF anode and activated carbon cathode exhibits high energy density (119 Wh kg−1) and ultra-long cycle stability (80.06 % capacity retention after 12,000 cycles).

Preparation and application of wood-supported piezocatalyst with high efficiency and stability via partial hydrolysis of wood cellulose and hemicellulose with Lewis acid

The conveniently recoverable piezocatalyst with self-floating and stable performance has drawn wide attention. Herein, MoS2 was anchored on 1-cm-square eucalyptus wood blocks via a facile hydrothermal/solvothermal process to fabricate two floating piezocatalysts, i.e., MoS2/unpretreated wood (MUW) and MoS2/pretreated wood (MPW). FeCl3 solution was used as a Lewis acid to pretreat the wood through partial hydrolyzing cellulose and hemicellulose for an purpose to creat rich micropores for MoS2 loading in the wood and to form MoFe heterojunction. The piezocatalytic properties and performance of the prepared wood were systematically studied. The scanning electron microscopy confirms MoS2 was anchored on wood surface. The macroscopic photos show that MoS2 penetrated through the MPW interior whereas it was only loaded on the wood surface layer. The X-ray photoelectron spectroscopy reveals the shift of Mo 3d and S 2p, verifying the heterojunction formation of MPW. The Fourier transform infrared spectra prove the partial hydrolysis of wood matrix. In comparison to MUW, MPW had excellent piezocatalytic property, wide pH adaptability, convenient recyclability and high stability. Sildenafil and Cr6+ ions could be completely removed in 20 and 15 min, respectively, by MPW. Contrastly, the removal efficiency of sildenafil and Cr6+ by MUW was 78.6 % and 68.3 % in 20 and 15 min, respectively. After five cycles of use, the removal ratio of sildenafil was 62.4 % by MUW and 90.5 % by MPW in 20 min. The mineralization efficiency of sildenafil reached 99.2 % in 30 min by MPW, and various types of N/S-containing intermediates were effectively degraded. The electron spin resonance characterization and active species scavenging experiments displayed that e− and •O2− were major active species responsible for Cr6+ piezoreduction by MUW and MPW, while •O2− and •OH were the dominant species accounting for sildenafil degradation by MUW and MPW, respectively. And •OH was not generated in the MUW piezocatalysis process. MPW had higher piezoelectric current and lower resistance at the electron transfer interface than MUW. Conclusively, this study paves a new pathway for preparing new floating piezocatalysts with easy recyclability and high stability from biomass for wastewater treatment.

Polymers of intrinsic microporosity with alkaline pyrrolidine and piperidine functional groups for high-temperature proton exchange membranes

Recently, the polymers of intrinsic microporosity (PIMs) exhibit good potential in high-temperature proton exchange membrane fuel cells (HT-PEMFCs) due to their tunable microporosity and functionality. In this paper, alkaline pyrrolidine and piperidine functional groups were introduced onto PIM-1 via the classical Mannich reaction obtaining PIM-1/PIM-Py-50 and PIM-1/PIM-MePi-50. It was found that, compared with commercial Meta-polybenzimidazole (m-PBI) membrane, PIMs membranes showed superior retention of phosphoric acid (PA) and conductivity due to their grafting alkaline groups and rich micropores. After equilibration under 80 °C/40 % relative humidity (RH) for 150 h, the PA retention of PA doped PIM-1/PIM-Py-50 (PIM-1/PIM-Py-50/PA) and PA doped PIM-1/PIM-MePi-50 (PIM-1/PIM-MePi-50/PA) membranes were 74.13 % and 68.52 %, respectively, much higher than PA doped m-PBI (m-PBI/PA) (45.73 %). PIMs membranes maintain excellent dimensional and conductivity stability at 160 °C operating conditions, e.g. PIM-1/PIM-Py-50/PA membrane showed area swelling retention and volume swelling retention of 84.69 % and 82.19 % after 230 h at 160 °C. In addition, with the similar PA uptake, PIMs membranes displayed higher conductivity and peak power density (PPD) at 160 °C. In the accelerated stress test (AST) the PPD of the fuel cell (FC) with the PIM-1/PIM-Py-50/PA membrane remained 81.25 % after 200 aggressive start-up/shut-down cycles at 80 °C. Therefore, PIM-based membranes alkaline groups exhibit a wider temperature operating window, providing theoretical guidance for the design and study of the next generation of high-temperature proton exchange membranes (HT-PEMs).

3D Carbon Microspheres with a Maze-Like Structure and Large Mesopore Tunnels Built From Rapid Aerosol-Confined Coherent Salt/Surfactant Templating.

Hierarchically porous carbons with tailor-made properties are essential for applications wherein rich active sites and fast mass transfer are required. Herein, a rapid aerosol-confined salt/surfactant templating approach is proposed for synthesizing hierarchically porous carbon microspheres (HPCMs) with a maze-like structure and large mesopore tunnels for high-performance tri-phase catalytic ozonation. The confined assembly in drying microdroplets is crucial for coherent salt (NaCl) and surfactant (F127) dual templating without macroscopic phase separation. The HPCMs possess tunable sizes, a maze-like structure with highly open macropores (0.3-30µm) templated from NaCl crystal arrays, large intrawall mesopore tunnels (10-45nm) templated from F127, and rich micropores (surface area >1000 m2 g-1 ) and oxygen heteroatoms originated from NaCl-confined carbonization of phenolic resin. The structure formation mechanism of the HPCMs and several influencing factors on properties are elaborated. The HPCMs exhibit superior performance in gas-liquid-solid tri-phase catalytic ozonation for oxalate degradation, owing to their hierarchical pore structure for fast mass transfer and rich defects and oxygen-containing groups (especially carbonyl) for efficient O3 activation. The reactive oxygen species responsible for oxalate degradation and the influences of several structure parameters on performance are discussed. This work may provide a platform for producing hierarchically porous materials for various applications.

Nanopore structures and controlling factors of the Early Cambrian shale reservoir in the Middle Yangtze Platform, South China

At present, the characteristics and controlling factors of nanopore structure in shale reservoirs are still not well understood owing to the concurrence of both organic matter (OM) and inorganic mineral (IM) pores. This issue is more prominent for the Early Cambrian shale in South China owing to the greatly variable nanopore structures of the samples from different areas. In this study, a set of Early Cambrian shale samples was taken from an exploration well in the Middle Yangtze Platform, a newly-determined shale gas play with a great potential outside the Sichuan Basin, their OM-removed (OMR) samples were obtained by a high-temperature oxidation method, and the pore structures of the bulk shales and their OMR-samples were analyzed by low-pressure gas adsorption experiments. The OM nanopore structure parameters of shale were calculated, and the controlling factors of OM and IM nanopores in the shale were investigated. The results show that the shale nanopores are mainly mesopores, their OM nanopores, especially OM micropores, are obviously more developmental compared with the IM nanopores. The TOC content is the dominant influencing factor of the shale nanopores. The brittle minerals support the formation of interparticle pores, and provide protection to OM pores. The clay minerals provide a certain amount of nanopores, but the strong compaction result in rich micropores. The carbonate minerals decrease the shale nanopores owing to the strong cementation. The favorable area of shale gas in the Early Cambrian strata in the studied area was predicted by the TOC content and preservation conditions.

3D porous graphene nanosheets as efficient additives for high-performance styrene–butadiene–styrene/crumb rubber blend-modified asphalt

Styrene-butadiene-styrene (SBS)/crumb rubber (CR) blend-modified asphalt is a desirable binder for pavement engineering with both environmental and economic benefits. However, the inherent incompatibility of SBS and CR in asphalt is still a critical issue. Herein, 3D porous graphene (3DPG) with high surface area and rich micropores as reinforced additive was investigated in SBS/CR blend-modified asphalt for the first time. The experimental results demonstrate that incorporating 3DPG can effectively improve the compatibility of SBS and CR in asphalt and thus significantly enhance the high and low temperature performance and fatigue resistance of the modified asphalt, compared with that without 3DPG. Theoretical calculations further reveal that the nanopores in graphene can endow graphene with electrophilic property, providing a capability of absorbing nonpolar molecules in asphalt while the non-pore part in graphene can interact with polar molecules by conventional π − π stacking. The two forces within graphene can break the original colloidal structures of asphalt, which is conductive to the homogenous formation of SBS network and swelling of CR in asphalt, significantly promoting the pavement performance of the modified asphalt. This work presents the great potential of 3DPG as new additive to solve the inherent incompatibility of SBS/CR blend-modified asphalt for high-grade pavement engineering.

MOF-derived carbon nanotubes as an highly active electrocatalyst for oxygen reduction reaction in alkaline and acidic media

The high-activity and low-cost electrocatalyst for oxygen reduction reaction (ORR) is important for proton exchange membrane fuel cells (PEMFCs). In this work, nitrogen-doped carbon nanotubes (Fe/N@CNT) prepared by pyrolyzing metal-organic skeleton materials Fe-ZIF-8 and g-C3N4 were used as electrocatalyst for oxygen reduction reaction. During the pyrolysis process, a large amount of nitrogen-containing gas is released which anchors Fe2+ ions in ZIF-8, forming an ORR catalytically active center (Fe-Nx). The as-synthesized Fe/N@CNT is a porous carbon material with high specific surface area (821.9 m2 g−1). The optimal Fe/N@CNT exhibits excellent ORR electrocatalytic activity with high half-wave potential (E1/2) of 0.892 V vs. RHE, which was 34 mV higher than that of commercial Pt/C (0.858 V vs. RHE) in 0.1 M KOH; E1/2 of Fe/N@CNT in 0.1 M HClO4 was 0.79 V vs. RHE, which was close to that of commercial Pt/C (0.88 V vs. RHE). Additionally, Fe/N@CNT shows long-term stability both in alkaline and acidic medium. The excellent electrocatalytic activity of Fe/N@CNT attributed to the rich micropores and mesopores structure and large specific surface area. This work offers a new approach to design and synthesize catalysts for ORR.

Preparation of porous organic polymers containing N or P atoms and their application in hydroformylation of 1-octene

Three kinds of porous organic polymers (POPs) containing N or P atoms were prepared, named N-POP, P-POP, and N + P-POP respectively and used as the supports for Rh catalysts. Their structures and compositions were fully understood by FTIR, XRD, EDX, 13C MAS NMR, 31P MAS NMR and XPS characterizations. Rich micropores and mesopores were detected in the polymers through N2 adsorption–desorption, SEM and TEM. Because of the bulk extrusion of triphenylphosphine (TPP) unit in Rh-P-POP and Rh-N + P-POP, the Rh-N-POP showed a larger BET surface area and larger pore volume. The characterization also proved that P atoms were oxidized partly to PO species. Their catalysis performances were tested in the hydroformylation of 1-octene and syngas, with isomerization as the main competing reaction. It was interesting to see that the inactive Rh-N-POP allowed Rh to combine with free ligands more easily, thus promoting the hydroformylation activity. The existence of TPP structure in the polymers, however, greatly promoted isomerization, with a weak hydroformylation activity, partly due to the partial oxidation of P atoms. On the other hand, the strong alkalinity and coordination ability of P atoms in the polymers made the association and dissociation of Rh with other free ligands difficult.

Metal-free carbon semi-tubes for oxygen reduction electrocatalysis

New carbon morphologies are desirable in the development of high-performance carbon-based electrocatalysts for cathodic oxygen reduction reaction (ORR) of polymer electrolyte membrane fuel cells. In this work, a carbon semi-tube (CST) is successfully constructed by polymerizing m-phenylenediamine (mPDA) using surfactant-assembled micelles as a soft template. After pyrolysis, the CST morphology is retained in the formed N-doped CST (N-CST) catalyst. This mPDA-induced catalyst can provide rich micropores, high N-content, and good conductivity, imbuing it with superior catalytic ORR activity, stability, and methanol tolerance to the commercial Pt/C catalyst. By using such a metal-free N-CST as a cathode catalyst, an alkaline polymer electrolyte fuel cell exhibits a maximum power density of about 200 mW cm−2. Furthermore, density functional theory (DFT) calculations suggest that high curvature can be greatly conducive to the excellent catalytic ORR activity by the induced strong OOH∗ adsorption on active sites through a strong dipole-electric field interaction.

Anisotropic reed-stem-derived hierarchical porous biochars supported paraffin wax for efficient solar-thermal energy conversion and storage

It is valuable to develop and utilize cheap and widely available biowaste for phase change energy storage with high value applications. In this work, by removing lignin and hydrolyzing cellulose with cellulase enzymes, the macropore channels of reed stems were made to be connected via rich micropores on the carbon wall during high-temperature carbonization process. By loading paraffin wax by vacuum impregnation, shape-stable composite phase change materials (CPCMs) with a three-dimensional multi-level pore structure were obtained. The CPCMs have high loading rate (93.45 wt%), high energy storage capacity (141.47 J/g) and good heat transfer performance. The anisotropic reed-stem-derived hierarchical porous biochars supported CPCMs has good solar absorption ability, and as high as 92.28 % solar-thermal conversion efficiency. The good thermal stability as well as cyclic thermal stability are beneficial for practical applications. In addition, this work can achieve the purpose of energy saving and carbon emission reduction via increasing the value utilization of biowaste.

Dual-carbon coupled three-dimensional superstructures with dominant mesopores targeting fast potassium-ion storage

Carbon materials with three-dimensional (3D) superstructure are a promising anode for potassium-ion batteries (PIBs) because of its rich micropores and defects. However, plenty of micropores often need more time to make electrolyte fully infiltrate, and their irreversible trapping effect will inevitably cause the loss of active K-ions upon cycling. Besides, excessive defects easily arouse poor conductivity because the absence of continuous graphite domains. Hence, dual-carbon coupled 3D superstructure is constructed by pyrolyzing the mixture of zeolitic imidazolate framework and polyvinylpyrrolidone (ZIF8@PVP). Since the preferential decomposition of external PVP, the micropores in ZIF8-derived carbon are effectively inhibited while keeping considerable mesopores, thus substantially shortening ions diffusion distance. Moreover, the decomposition and shrinkage of ZIF8 particles in return prompt the PVP-derived carbon to create more defects, which favors the adsorption storage of K-ions. Not only that, the metallic Zn can catalyze the formation of continuous graphite domains, endowing fast electron migration rate. Accordingly, the optimized product not only delivers an excellent rate (188.2 mAh g−1 at 2 A g−1) and cyclability (over 1800 cycles) in K-half cells, but presents a high energy density (181.5 Wh kg−1) in potassium-ion hybrid capacitors.

Preparation of hierarchical porous carbon by pyrolyzing sargassum under microwave: The internal connection between structure−oriented regulation and performance optimization of supercapacitors

To find an effective correlation between the preparation process and the application performance of symmetric supercapacitors, the relationship between the structural characteristics of biomass porous carbon and the electrochemical performances of supercapacitors was studied. Based on a response surface experimental design, the pore structure of biochar produced by the microwave pyrolysis of sargassum was adjusted through the collaborative optimization of key parameters, and graded sargassum porous carbon (SPC) with different pore characteristics was successfully prepared. Three representative samples, SPC−1, SPC−2, and SPC−3, were selected by systematically exploring the effects of the specific surface area (SSA), pore volume (Vtotal), and pore size distribution on the electrochemical performances. The SSA and Vtotal values of SPC−1 were 1500.50 m2 g−1 and 1.0513 cm3 g−1, respectively. The large number of micropores provided space for electronic storage, allowing it to have an excellent electronic storage capacity. The SSA of SPC−2 was 2019.90 m2 g−1, and Vtotal was 1.2241 cm3 g−1. The rich micropores resulted in a good charge–discharge rate. The SSA of SPC−3 was as high as 2103.20 m2 g−1, and Vtotal was 1.4756 cm3 g−1. The micron−level mesopores between the SPC−3 carbon skeletons acted as ion buffer reservoirs to shorten the ion diffusion distance and produce excellent rate performances. Subsequently, the morphology and surface properties of porous carbon samples were characterized. The study revealed that hierarchical porous carbon materials with excellent properties must achieve a balance of the microstructure and surface properties and their influence on the electrochemistry. A higher degree of graphitization could bring about a high pore regularity, thereby optimizing the ion transport kinetics. Heteroatoms could increase redox active surface sites and provide additional pseudocapacitance, but the resulting defect structure formed a large number of pores with high edge roughness in the carbon material, which had a certain negative impact on the capacity properties of the materials. The above findings can provide technical support and a theoretical basis for controlling the pore networks and directionally optimizing the performances of supercapacitors by adjusting the pore structure of biochar.

Zinc-guided 3D graphene bulk materials for high-performance binder-free anodes of potassium-ion batteries

Potassium ion batteries are promisingly proposed for the large cale energy storage. However, potassium with large ion radius causes severe volumetric expansion of anodes during charging, which deteriorates the rate and the cycling performances of batteries. Herein, a honeycomb-like graphene monolith with rich micropores is prepared. The monolith is further applied as the binder-free anode for potassium ion batteries. It shows the remarkable rate performance with a capacity of 180 mAh g−1 at a current density of 10 A g−1, and it can stably run for 4000 cycles at 1 A g−1. Kinetic studies and theoretical analyses reveal that the large graphitic interlayer spacing, the nitrogen doping, and the 3D network structure can significantly promote the diffusion rate, the absorption of potassium ions, as well as the transports of electrons and ions. The graphene-based potassium ion batteries can thus boost the development of renewable energies.

Synthesis of coal tar pitch-derived heteroatom-doped porous carbon materials for aqueous zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors (ZHSs), which combine the superiority of batteries and supercapacitors, will become a new development direction in the field of energy storage. The development of ZHSs with high capacity and high stability can be further promoted by heteroatom doping or structural modification of cathode materials. Herein, N,O,P co-doped porous carbon materials were synthesized by a facile method using coal tar pitch as precursor, aluminum phosphate as template, and sodium hydroxide as activator. Due to the high specific surface area and abundant micropores, the heteroatom-doped porous carbon materials were employed as cathode for aqueous ZHSs to study the electrochemical performance. Benefitted from the rich micropores and heteroatom doping, the porous carbon electrodes exhibit an outstanding electrochemical performance and deliver a large specific capacitance of 113.3 mA h g−1 at 0.1 A g−1. In addition, the porous carbon electrode shows a high energy density of 64.9 Wh kg−1 and a high power density of 1.23 kW kg−1, which outperforms most aqueous ZHS energy storage systems previously reported. Interestingly, after 5000 cycles at 1 A g−1, the specific capacity is about 36% higher than the original capacity and the coulomb efficiency still remains nearly 100%. The article may provide a new insight into exploring cathode materials for high-performance aqueous rechargeable zinc-ion energy storage devices.

Conjugated microporous polymer membranes for chemical separations

• Conjugated microporous polymer (CMP) membranes for chemical separations are reviewed. • The historical development of CMPs is discussed. • Fabrication routes of CMP membranes are critically compared and reviewed. • Applications of CMP membranes are comprehensively summarized. • The inference on the future prospects of CMPs as membranes is provided. Conjugated microporous polymers (CMPs) are a unique class of porous organic materials, which are constructed with π-conjugation structures leading to intrinsic micropores. The CMPs properties such as high surface area, intrinsic and rich micropores, interlocking and rigid structure, extensive π-conjugation and tunable band-gap, chemical and thermal stability, together with tailored functionalities, contribute to its abundant potential for application in fields such as photocatalysis, optoelectronics, energy storage, and chemical sensors. Recently, CMPs have gained importance in the field of membranes for chemical separation. In this review, we briefly discuss the historical development of CMPs, followed by a detailed description of the progress in state-of-the-art design, preparation, and application of CMPs in membranes. Additionally, we provide inference on the future prospects of CMPs as membranes.

Convenient synthesis of a hyper-cross-linked polymer via knitting strategy for high-performance solid phase microextraction of polycyclic aromatic hydrocarbons

Precise quantifications of trace polycyclic aromatic hydrocarbons (PAHs) have been the focus in recent years due to the low concertation in environment and greatly potential damage on human health. The Rubrene (Rub) was used as the raw material to obtain a hyper-cross-linked polymer (HCP-Rub) via Friedel-Crafts reaction, which was further fabricated as a novel SPME coating. The abundant benzene rings on Rub could act as reactive sites, leading to the facile synthesis of HCP-Rub. Moreover, the as-prepared HCP-Rub possessed rich micropores, strong hydrophobicity and large conjugated structure, which made it an ideal candidate for the efficient enrichments of PAHs. The extraction efficiencies of HCP-Rub coated SPME fiber for PAHs were 1.5–16.4 times of the commercial PDMS fiber (100 μm), and 1.2–1.6 times of the commercial PDMS/DVB (65 μm) fiber, respectively. Under optimal conditions, the HCP-Rub coated fiber demonstrated high enhancement factors, ranging from 1331 to 3089. It was further coupled with gas chromatography-mass spectrometry (GC–MS) to establish an analytical method with wide linear ranges (5–1000 ng·L−1) and low detection limits (0.11–0.98 ng·L−1). Finally, the method was successfully applied to the determinations of trace PAHs in environmental water samples with good recoveries (83.7–108%).

Formation and occurrence characteristics of methane hydrate in the complex system of sodium dodecyl sulfate and porous media

ABSTRACT In recent years, porous media have attracted a lot of attention due to the enhanced kinetics of hydrate formation. However, how porous media promote hydrate formation is still an open topic. In this study, two different porous media, activated alumina and glass beads (average particle size 1, 3, 5 mm), were mixed with sodium dodecyl sulfate (SDS) to promote methane hydrate formation (275.15 K, 6 MPa). The smaller the particle size is, the better the promoting effect of porous media is, corresponding to faster formation kinetics and higher gas consumption. The average hydrate formation rate (2.3 mmol/min) and T90 (136 min) in the 1 mm activated alumina system was 2.6 and 0.4 times higher than the average hydrate formation rate (0.9 mmol/min) and T90 (349 min) in the 3 mm activated alumina system, respectively. Better performance of activated alumina particles than that of glass beads because of its rich micropores and unique electric double layer distribution in solution. The gas storage density of hydrate in the 1 mm alumina system can reach 129.13 Vg/Vh, while the highest gas storage density of hydrate in the 1 mm glass bead system was 122.35 Vg/Vh, which was similar to that of hydrate in the 3 mm activated alumina system (123.63 Vg/Vh). The gas consumption of the system was not affected by mass transfer but was controlled by particle size and solution volume with the presence of SDS. Under supersaturated and saturated conditions, it is found that the porous media bed and hydrate layer moved upward under the action of capillary force and methane gas driving force. This work provides a reference for the formation and occurrence of hydrates with the presence of porous media and surfactants.

OPTIMIZING THE ENVIRONMENTAL FACTORS FOR THE AFFINITY OF 222Rn WITH CARBON FIBERS

Radon (222Rn) is a member of the decay chain of 238U. It has been well documented that 222Rn is known to present a risk of lung cancer once inhaled. For practical implementation, this study makes use of activated carbon fibers (ACFs) to uptake 222Rn through environmental variations in the temperature, dosage of the adsorbent and circulate conditions. Here, three ACF samples were prepared via different carbonization and activation temperatures from 850 °C to 900 °C. The observed adsorption characteristics show that low temperature and high surface contact of an adsorbent with rich micropores allow the maximum adsorption of 222Rn. No such correlation was observed in the case of increasing the circulate conditions. However, there was a direct influence on the maximum adsorption capacity once the circulate conditions decreased. In summary, these findings expand the understanding of the adsorption, dependency on the factors and a proper carbonaceous-material design for reducing 222Rn.

Magnetic porous nano‐carbon catalysts supported silver nanoparticles derived from chitin and their application in catalytic reduction reactions

AbstractThe exploitation of recycled carbonaceous catalysts from renewable biomass resources such as chitin is a crucial issue for the development of the sustainable society. In this article, the chitin‐based N and O doped carbon microspheres (ChC) were fabricated by a simple dissolution, sol–gel transformation, and the carbonization methods. Subsequently, the novel magnetic Ag‐Fe3O4@chitin‐based carbon microspheres catalyst (MChC) was successfully constructed through the in situ redox reaction. The as‐prepared MChC possessed rich micropores with high‐surface area, and a narrow size distribution (50–120 μm). The Ag‐Fe3O4 nanoparticles were immobilized through the interaction with C, N, and O atoms in the pores of MChC. The reduction of 4‐nitrophenol was applied to evaluate the catalytic activity of MChC. 4‐Nitrophenol (4‐NP) could be fully reduced to 4‐aminophenol (4‐AP) in 5 min with the catalyst MChC‐45. Moreover, MChC could be collected in solution with an external magnet in 8 s and remained relatively high‐catalytic activity after 10 cycle times. This work provided novel ideas for the fabrication of doped carbon material from biomass and promoted its utilization in nanocatalytic applications.

Preparation of Cotton Fiber-derived Porous-carbon Materials and Their Application as High-performance Supercapacitors

ABSTRACT In this paper, high-surface area porous carbons are produced from cotton fibers by pre-oxidation and high temperatures activation pyrolysis treatment process based on the use of K2CO3 as pore-forming agent, and the more micro-pores were formed by adding ZnCl2 during the pyrolysis treatment process. The AC-K has plentiful bigger micropores or the macropores, AC-KZn has rich micropores and the certain number of mesopores. The AC-KZn shows excellent supercapacitance properties and cycle behavior of 5000 cycles, a high specific capacitance of 135Fg −1 can be achieved, which is higher than that of the AC-K carbon electrode.