High surface carbon aerogels with hierarchical and tunable pore structure were prepared using ionic liquid as carbon precursor via a simple salt templating method. The as-prepared carbon aerogels were characterized by nitrogen sorption measurement and scanning electron microscopy. Through instant visual observation experiments, it was found that salt eutectics not only serve as solvents, porogens, and templates, but also play an important role of foaming agents in the preparation of carbon aerogels. When the pyrolyzing temperature rises from 800 to 1000°C, the higher temperature deepens the carbonization reaction further to form a nanoporous interconnected fractal structure and increase the contribution of super-micropores and small mesopores and improve the specific surface area and pore volume, while having few effects on the macropores. As the mass ratio of ionic liquid to salt eutectics drops from 55% to 15%, that is, the content of salt eutectics increases, the salt eutectics gradually aggregate from ion pairs, to clusters with minimal free energy, and finally to a continuous salt phase, leading to the formation of micropores, uniform mesopores, and macropores, respectively; these processes cause BET specific surface area initially to increase but subsequently to decrease. With the mass ratio of ionic liquids to salts at 35% and carbonization temperature at 900°C, the specific surface area of the resultant carbon aerogels reached 2309 m2 g–1. By controlling the carbonization temperature and mass ratio of the raw materials, the hierarchically porous architecture of carbon aerogels can be tuned; this advantage will promote their use in the fields of electrodes and adsorption.

During a long-term operation of polymer electrolyte membrane fuel cells(PEMFCs), the fuel cell performance may degrade due to severe agglomeration and dissolution of metal nanoparticles in the cathode. To enhance the electrochemical durability of metal catalysts and to prevent the particle agglomeration in PEMFC operation, this paper proposes a hybrid catalyst structure composed of PtCo alloy nanoparticles encapsulated by porous carbon layers. In the hybrid catalyst structure, the dissolution and migration of PtCo nanoparticles can be effectively prevented by protective carbon shells. In addition, O2 can properly penetrate the porous carbon layers and react on the active Pt surface, which ensures high catalytic activity for the oxygen reduction reaction. Although the hybrid catalyst has a much smaller active surface area due to the carbon encapsulation compared to a commercial Pt catalyst without a carbon layer, it has a much higher specific activity and significantly improved durability than the Pt catalyst. Therefore, it is expected that the designed hybrid catalyst concept will provide an interesting strategy for development of high-performance fuel cell catalysts.

The stereotype of flexible MOFs(Amino-MIL-53) and carbonized porous carbon prepared from renewable resources is successfully synthesized for CO2 reduction application. The textural properties of these microporous materials are investigated, and their CO2 storage capacity and separation performance are evaluated. Owing to the combined effects of CO2-Amino interaction and its flexibility, a CO2 uptake of 2.5 mmol g−1 is observed in Amino-MIL-53 at 20 bar 298 K. In contrast, CH4 uptake in Amino-MIL-53 is very low up to 20 bar, implying potential sorbent for CO2/CH4 separation. Carbonized samples contain a small quantity of metal residues(K, Ca, Mg, S), resulting in naturally doped porous carbon. Due to the trace metal, even higher CO2 uptake of 4.7 mmol g−1 is also observed at 20 bar 298 K. Furthermore, the CH4 storage capacity is 2.9 mmol g−1 at 298 K and 20 bar. To evaluate the CO2 separation performance, the selectivity based on ideal adsorption solution theory for CO2/CH4 binary mixtures on the presented porous materials is investigated.

Hierarchically porous, chemically activated carbon materials are readily derived from biomass using hydrothermal carbonization (HTC) and chemical activation processes. In this study, empty fruit bunches (EFB) were chosen as the carbon source due to their sustainability, high lignin-content, abundance, and low cost. The lignin content in the EFB was condensed and carbonized into a bulk non-porous solid via the HTC process, and then transformed into a hierarchical porous structure consisting of macro- and micropores by chemical activation. As confirmed by various characterization results, the optimum activation temperature for supercapacitor applications was determined to be 700°C. The enhanced capacitive performance is attributed to the textural property of the extremely high specific surface area of 2861.4 m2 g–1. The prepared material exhibited hierarchical porosity and surface features with oxygen functionalities, such as carboxyl and hydroxyl groups, suitable for pseudocapacitance. Finally, the as-optimized nanoporous carbons exhibited remarkable capacitive performance, with a specific capacitance of 402.3 F g–1 at 0.5 A g–1, a good rate capability of 79.8% at current densities from 0.5 A g–1 to 10 A g–1, and excellent life cycle behavior of 10,000 cycles with 96.5% capacitance retention at 20 A g–1.

Nanoporous carbon structures were synthesized by pyrolysis of grass as carbon precursor. The synthesized carbon has high surface area and pore volume. The carbon products were acid functionalized and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller, transmission electron microscopy, and Energy Dispersive X-ray microanalysis. Acid functionalized nanoporous carbon was explored for use in removal of toxic Cr(VI) ions from aqueous media. An adsorption study was done as a function of initial concentration, pH, contact time, temperature, and interfering ions. The experimental equilibrium data fits well to Langmuir isotherm model with maximum monolayer adsorption capacity of 35.335 mg/g. The results indicated that removal obeys a pseudo-second-order kinetic model, and that equilibrium was reached in 10 min. A desorption study was done using NaOH. The results of the present study imply that acid functionalized nanoporous carbon synthesized from grass is an efficient, renewable, cost-effective adsorbent material for removal of hexavalent chromium due to its faster removal rate and reusability.

Monolithic carbon foams with hierarchical porosity were prepared from polyurethane templates and resol precursors. Mesoporosity was achieved through the use of soft templating with surfactant Pluronic F127, and macroporosity from the polyurethane foams was retained. Conditions to obtain high porosity materials were optimized. The best materials have high specific surface areas (380 and 582 m2 g–1, respectively) and high electrical conductivity, which make them good candidates for supports in sensors. These materials showed an almost linear dependence between the potential and the pH of aqueous solutions.

High pollutant-loading capacities (up to 319 times its own weight) are achieved by three-dimensional (3D) macroporous, slightly reduced graphene oxide (srGO) sorbents, which are prepared through ice-templating and consecutive thermal reduction. The reduction of the srGO is readily controlled by heating time under a mild condition (at 1 10–2 Torr and 200°C). The saturated sorption capacity of the hydrophilic srGO sorbent (thermally reduced for 1 h) could not be improved further even though the samples were reduced for 10 h to achieve the hydrophobic surface. The large meso- and macroporosity of the srGO sorbent, which is achieved by removing the residual water and the hydroxyl groups, is crucial for achieving the enhanced capacity. In particular, a systematic study on absorption parameters indicates that the open porosity of the 3D srGO sorbents significantly contributes to the physical loading of oils and organic solvents on the hydrophilic surface. Therefore, this study provides insight into the absorption behavior of highly macroporous graphene-based macrostructures and hence paves the way to development of promising next-generation sorbents for removal of oils and organic solvent pollutants.

Co-embedded graphitic porous carbon nanofibers(Co-GPCNFs) are synthesized by using an electrospinning method. Their morphological, structural, electrochemical, and photovoltaic properties are investigated. To obtain the optimum condition of Co-GPCNFs for dye-sensitized solar cells(DSSCs), the amount of cobalt precursor in an electrospinning solutuion are controlled to be 0 wt%(conventional CNFs), 1 wt%(sample A), and 3 wt%(sample B). Among them, sample B exhibited a high degree of graphitization and porous structure compared to conventional CNFs and sample A, which result in the performance improvement of DSSCs. Therefore, sample B showed a high current density(JSC, 12.88 mA/cm2) and excellent power conversion efficiency(PCE, 5.33 %) than those of conventional CNFs(12.00 mA/cm2, 3.78 %). This result can be explained by combined effects of the increased contact area between the electrode and elecytolyte caused by improved porosity and the increased conductivity caused by the formation of a high degree of graphitization. Thus, the Co-GPCNFs may be used as a promising alternative of Pt-free counter electrode in DSSCs.

To improve the methanol electro-oxidation in direct methanol fuel cells(DMFCs), Pt electrocatalysts embedded on porous carbon nanofibers(CNFs) were synthesized by electrospinning followed by a reduction method. To fabricate the porous CNFs, we prepared three types of porous CNFs using three different amount of a styrene-co acrylonitrile(SAN) polymer: 0.2 wt%, 0.5 wt%, and 1 wt%, respectively. A SAN polymer, which provides vacant spaces in porous CNFs, was decomposed and burn out during the carbonization. The structure and morphology of the samples were examined using field emission scanning electron microscopy and transmission electron microscopy and their surface area were measured using the Brunauer- Emmett-Teller(BET). The crystallinities and chemical compositions of the samples were examined using X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical properties on the methanol electro oxidation were characterized using cyclic voltammetry and chronoamperometry. Pt electrocatalysts embedded on porous CNFs containing 0.5 wt% SAN polymer exhibited the improved methanol oxidation and electrocatalytic stability compared to Pt/conventional CNFs and commercial Pt/ C(40 wt% Pt on Vulcan carbon, E-TEK).

The composite of porous silicon (Si) and amorphous carbon (C) is prepared by pyrolysis of a nano-porous Si + pitch mixture. The nano-porous Si is prepared by mechanical milling of magnesium powder with silicon monoxide (SiO) followed by removal of MgO with hydrochloric acid (etching process). The Brunauer-Emmett-Teller (BET) surface area of porous Si (64.52 m2g−1) is much higher than that before etching Si/MgO (4.28 m2g−1) which indicates pores are formed in Si after the etching process. Cycling stability is examined for the nano-porous Si + C composite and the result is compared with the composite of nonporous Si + C. The capacity retention of the former composite is 59.6% after 50 charge/discharge cycles while the latter shows only 28.0%. The pores of Si formed after the etching process is believed to accommodate large volumetric change of Si during charging and discharging process.

Well-distributed ruthenium (Ru) nanoparticles decorated on porous carbon nanofibers (CNFs) were synthesized using an electrospinning method and a reduction method for use in high-performance elctrochemical capacitors. The formation mechanisms including structural, morphological, and chemical bonding properties are demonstrated by means of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). To investigate the optimum amount of the Ru nanoparticles decorated on the porous CNFs, we controlled three different weight ratios (0 wt%, 20 wt%, and 40 wt%) of the Ru nanoparticles on the porous CNFs. For the case of 20 wt% Ru nanoparticles decorated on the porous CNFs, TEM results indicate that the Ru nanoparticles with ~2-4 nm size are uniformly distributed on the porous CNFs. In addition, 40 wt% Ru nanoparticles decorated on the porous CNFs exhibit agglomerated Ru nanoparticles, which causes low performance of electrodes in electrochemical capacitors. Thus, proper distribution of 20 wt% Ru nanoparticles decorated on the porous CNFs presents superior specific capacitance (~280.5 F/g at 10 mV/s) as compared to the 40 wt% Ru nanoparticles decorated on the porous CNFs and the only porous CNFs. This enhancement can be attributed to the synergistic effects of well-distributed Ru nanoparticles and porous CNF supports having high surface area.

In this study, synthetic viscose rayon fabric has been used for preparing activated carbon fabric (ACF), impregnated with different concentrations of H3PO4. The effect of H3PO4 im-pregnation on the weight yield, surface area, pore volume, chemical composition and mor-phology of ACF were studied. Experimental results revealed that both Brunauer-Emmett-Teller surface area and micropore volume increased with increasing H3PO4 concentration; however, the weight yield and microporosity (%) decreased. It was observed that samples impregnated at 70°C (AC-70) give higher yield and higher microporosity as compared to 30°C (AC-30). The average pore size of the ACF also gradually increases from 18.2 to 19 and 16.7 to 20.4 Å for 30°C and 70°C, respectively. The pore size distribution of ACF was also studied. It is also concluded that the finalACF strength is dependent on the concentra-tion of impregnant.

Carbon nanofibers (CNFs) with diameters in the submicron and nanometer range exhibit high specific surface area, hierarchically porous structure, flexibility, and super strength which allow them to be used in the electrode materials of energy storage devices, and as hybrid-type filler in carbon fiber reinforced plastics and bone tissue scaffold. Unlike catalytic synthesis and other methods, electrospinning of various polymeric precursors followed by stabilization and carbonization has become a straightforward and convenient way to fabricate continuous CNFs. This paper is a comprehensive and brief review on the latest advances made in the development of electrospun CNFs with major focus on the promising applications accomplished by appropriately regulating the microstructural, mechanical, and electrical properties of as-spun CNFs. Additionally, the article describes the various strategies to make a variety of carbon CNFs for energy conversion and storage, catalysis, sensor, adsorption/separation, and biomedical applications. It is envisioned that electrospun CNFs will be the key materials of green science and technology through close collaborations with carbon fibers and carbon nanotubes.

Potassium hydroxide-activated carbons (CK21, CK11, and CK12) were prepared from pis-tachio nutshells. Physicochemical properties of activated carbons were characterized by TGA, pHpzc, Fourier transform infrared spectroscopy, scanning electron microscopy, and N2-adsorption at -196°C. The examinations showed that activated carbons have high sur-face area ranging between 695-1218 m2/g, total pore volume ranging between 0.527-0.772 mL/g, and a pore radius around 1.4 nm. The presence of acidic and basic surface C-O groups was confirmed.Batch adsorption experiments were carried out to study the effects of adsorbent dosage, temperature, initial concentration of adsorbate, and contact time on deltamethrin adsorption by activated carbons. The kinetic studies showed that the adsorp-tion data followed a pseudo-second order kinetic model. The Langmuir model showed a maximum adsorption capacity of 162.6 mg/g at 35°C on CK12. Thermodynamic studies indicated that adsorption was spontaneous and increased with temperature, suggesting an endothermic process.

In this study, activated carbons nanofibers (ACNFs) were prepared from polyacrylonitrile-based nanofibers by physical (H2O and CO2) and chemical (KOH) activation. The surface and structural characteristics of the porous carbon were observed by scanning electron microscopy and X-ray diffraction, respectively. Pore characteristics were investigated by N2/77K adsorption isotherms. The specific surface area of the physically ACNFs was increased up to 2400m2/g and the ACNFs were found to be mainly composed of micropore structures. Chemical activation using KOH produced ACNFs with high specific surface area (up to 2500m2/g), and the micropores were mainly found in the ACNFs. The physically and chemically ACNFs showed both mainly type I from the International Union of Pure and Applied Chemistry classification.

Nanoporous non-woven carbon fibers for a gas sensor were prepared from a pitch/polyacrylonitrile (PAN) mixed solution through an electrospinning process and their gas-sensing properties were investigated. In order to create nanoscale pores, magnesium oxide (MgO) powders were added as a pore-forming agent during the mixing of these carbon precursors. The prepared nanoporous carbon fibers derived from the MgO pore-forming agent were characterized by scanning electron microscopy (SEM), N2-adsorption isotherms, and a gas-sensing analysis. The SEM images showed that the MgO powders affected the viscosity of the pitch/PAN solution, which led to the production of beaded fibers. The specific surface area of carbon fibers increased from 2.0 to 763.2m2/g when using this method. The template method therefore improved the porous structure, which allows for more efficient gas adsorption. The sensing ability and the response time for the NO gas adsorption were improved by the increased surface area and micropore fraction. In conclusion, the carbon fibers with high micropore fractions created through the use of MgO as a pore-forming agent exhibited improved NO gas sensitivity.

As a pore precursor, carbon black with different content of 0 to 60 vol% were added to (Ba,Sr) powder. Porous (Ba,Sr) ceramics were prepared by pressureless sintering at for 1h under air. Effects of carbon black content on the microstructure and PTCR characteristics of porous (Ba,Sr) ceramics were investigated. The porosity of porous (Ba,Sr) ceramics increased from 6.97% to 18.22% and the grain size slightly decreased from to with increasing carbon black contents. PTCR jump of the (Ba,Sr) ceramics prepared by adding carbon black was more than , and slightly increased with increasing carbon black. The PTCR jump in the (Ba,Sr) ceramics prepared by adding 40 vol% carbon black showed an excellent value of , which was above two times higher than that in (Ba,Sr) ceramics. These results correspond with Heywang model for the explanation of PTCR effect in (Ba,Sr) ceramics. It was considered that carbon black is an effective additive for preparing porous based ceramics. It is believed that newly prepared (Ba,Sr) cermics can be used for PTC thermistor.

In this study, porous electrospun carbon fibers were prepared by electrospinning with PAN and MgCl2, as a MgO precursor. MgO was selected as a substrate because of its chemical and thermal stability, no reaction with carbon, and ease of removal after carbonization by dissolving out in acidic solutions. MgCl2 was mixed with polyacrylonitrile (PAN) solution as a precursor of MgO with various weight ratios of MgCl2/PAN. The average diameter of porous electrospun carbon fibers increased from 1.3 to 3 μm, as the MgCl2 to PAN weight ratio increased. During the stabilization step, MgCl2 was hydrolyzed to MgOHCl by heat treatment. At elevated temperature of 823 K for carbonization step, MgOHCl was decomposed to MgO. Specific surface area and pore structure of prepared electrospun carbon fibers were decided by weight ratio of MgCl2/PAN. The amount of hydrogen storage increased with increase of specific surface area and micropore volume of prepared electrospun carbon fibers.