BET Specific Surface Area Research Articles

Optimization of the Li-ion conductivity of UiO-66 coated LiCoPO4 nanocomposites

LiCoPO4 coated by different concentrations of UiO-66 (LiCoPO4@xUiO-66) samples, with x = 0.0, 0.01, and 0.02, were successfully synthesized. XRD spectra confirmed that the samples have a single orthorhombic phase with the Pnmɑ space group. The microstructure of these samples was investigated via TEM. Besides, all expected elements appeared in the XRF spectra in the same stoichiometry ratios of the raw materials. The XAS spectra of UiO-66-coated LiCoPO4 samples with varying contents are similar to that of pure LiCoPO4 both in terms of the position of the absorption edge and the highest position. The values of BET-specific surface areas and meso-to macropore volume of the LiCoPO4@UiO-66 composites increased with UiO-66 additions. Interestingly, the ionic conductivity of LiCoPO4@UiO-66 composites increased by UiO-66 additions. Because of the UiO-66 coating on LiCoPO4, these composites have a 3D tunable porous structure while retaining their composition and crystal structure. This 3D-tunable porous structure easily allows Li+ ion migration. The observed results exhibit a new type of synthetic post-modification of the organic/inorganic UiO-66 subunits, yielding a unique electrode possibly suited for Li-ion batteries.

ZnO-ZnFe2O4 Catalyst for Hydrogen Production from Methanol Steam Reforming

In this study, ZnFe2O4 and ZnO-ZnFe2O4 catalysts were prepared using the glycine–nitrate process (GNP). The prepared ZnFe2O4 and ZnO-ZnFe2O4 catalyst powders were characterized using a scanning electron microscope, transmission electron microscope, XRD diffraction studies, and selected area diffraction pattern studies. In addition, the specific surface area was measured using a Brunauer–Emmett–Teller specific surface area analysis. The hydrogen reduction in different temperature ranges was analyzed using the H2 temperature-programmed reduction technique. The specific surface area of the ZnFe2O4 was 5.66 m2/g, and the specific surface area of the ZnO-ZnFe2O4 was 8.20 m2/g at a G/N ratio of 1.5 and at a G/N ratio of 1.7, respectively. The specific surface area of the ZnFe2O4 was 6.03 m2/g, and the specific surface area of the ZnO-ZnFe2O4 was 11.67 m2/g. The ZnFe2O4 and ZnO-ZnFe2O4 were found to have the best catalytic effect at 500 °C. In particular, the highest H2 generation rate of the ZnO-ZnFe2O4 (GN = 1.7) at 500 °C was 7745 mL STP min−1 g-cat−1. Moreover, the ZnO-ZnFe2 O4 catalyst demonstrated good H2 selectivity and stability during the process of steam reforming methanol. Therefore, the ZnO-ZnFe2O4 catalyst powder exhibited high catalytic activity due to the good dispersibility of the ZnO, which increased the specific surface area of the catalyst. In the future, the catalyst can be applied to the steam reforming of methanol for industrial purposes.

Nitrogen, nickel and graphene oxide doped carbon xerogel as an active electrode of an electrochemical capacitor

N-, Ni-, and graphene oxide (GO)-doped carbon xerogel were synthesized from melamine-resorcinol-formaldehyde gels by drying followed by pyrolysis at 950 °C. The mass of nickel and GO in carbon xerogel, formed after carbonization was 5 and 1%, respectively. The obtained product was characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The characteristics were completed by measurements of BET specific surface area as well as pore distribution. For graphene oxide and nickel doped carbon xerogel, a decrease in the BET surface area of about 2% compared to unmodified carbon xerogel was observed with a simultaneous increase of cumulative pore volume and average pore diameter of about 50 and 32%, respectively. Electrochemical properties of doped carbon xerogel were evaluated in 6 M KOH by cyclic voltammetry (CV) and galvanostatic modes. It was revealed, that the highest specific capacitance of 222 Fg−1 was reached for N-Ni-GO-doped carbon xerogel during the process of galvanostatic charge-discharge (GCD). Moreover, this sample also exhibited 100% stability during GCD and about 98% stability during 3000 cycling tests.Graphical abstractCharacterization of morphology, structure and electrochemical properties of xerogels where:MRF-CX - melamine-resorcinol-formaldehyde xerogel,MRF-GO-Ni-CX - melamine-resorcinol-formaldehyde-graphene oxide-nickel xerogel

Deciphering the role of pristine and Ni ions substituted Co3O4 nanoparticles with altered structural, magnetic and dielectric traits towards elevated photosensing and photocatalytic activity

ABSTRACT Pure and nickel (Ni) doped cobalt oxide nanoparticles were employed by the co-precipitation method to present the structural, optical, and photocatalytic characteristics of NixCo3-xO4 nanoparticles (x = 0, 0.05, 0.1, and 0.3) for organic pollutant photodegradation. X-ray diffraction (XRD) was employed on NixCo3-xO4 samples with particle sizes ranging from 14 to 22 nm, confirming the occurrence of cubic phase. In addition, particle size was calculated by Debye Scherrer, Williamson-Hall (W-H) and Halder methods, respectively. The Fourier transform infrared (FTIR) analyses of all samples characterised the inherent lattice vibrations of spinel structures octahedral and tetrahedral sites, respectively. FESEM image depicts irregular-shaped clusters and EDX confirmed the presence of Ni, Co and O elements. The mesoporous nature of the pores and high BET specific surface area indicated the presence of several active sites, proving their viability as photocatalysts. UV-Vis spectrophotometer was utilised to measure the optical properties, which included recording absorption spectra and computing optical parameters. The photocatalytic activities of the pure Co3O4 and NixCo3-xO4 photocatalysts were studied by the degradation of a series of four dyes (Congo Red, Tartrazine, Rhodamine B, and Methylene Blue) solution under visible light irradiation. Compared to pure cobalt oxide, Ni-incorporated Co3O4 exhibits a substantially higher photocatalytic efficiency that increases with Ni doping concentration. The photocatalysts displayed superior recycling stability, retaining high performance after three cycles. The photosensing properties were investigated under UV light, and a considerable photocurrent enhancement was observed. As a result, it is illustrated that Ni-doped cobalt oxide NPs are a potential material for the fabrication of photosensitive devices.

Ppb-Level Hydrogen Sulfide Gas Sensor Based on the Nanocomposite of MoS2 Octahedron/ZnO-Zn2SnO4 Nanoparticles.

Hydrogen sulfide (H2S) detection is extremely necessary due to its hazardous nature. Thus, the design of novel sensors to detect H2S gas at low temperatures is highly desirable. In this study, a series of nanocomposites based on MoS2 octahedrons and ZnO-Zn2SnO4 nanoparticles were synthesized through the hydrothermal method. Various characterizations such as X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectrum (XPS) have been used to verify the crystal phase, morphology and composition of synthesized nanocomposites. Three gas sensors based on the nanocomposites of pure ZnO-Zn2SnO4 (MS-ZNO-0), 5 wt% MoS2-ZnO-Zn2SnO4 (MS-ZNO-5) and 10 wt% MoS2-ZnO-Zn2SnO4 (MS-ZNO-10) were fabricated to check the gas sensing properties of various volatile organic compounds (VOCs). It showed that the gas sensor of (MS-ZNO-5) displayed the highest response of 4 to 2 ppm H2S and fewer responses to all other tested gases at 30 °C. The sensor of MS-ZNO-5 also displayed humble selectivity (1.6), good stability (35 days), promising reproducibility (5 cycles), rapid response/recovery times (10 s/6 s), a limit of detection (LOD) of 0.05 ppm H2S (Ra/Rg = 1.8) and an almost linear relationship between H2S concentration and response. Several elements such as the structure of MoS2, higher BET-specific surface area, n-n junction and improvement in oxygen species corresponded to improving response.

Adsorption of methylene blue from textile industrial wastewater using activated carbon developed from Rumexabyssinicus plant

Methylene blue (MB) is abundantly found in textile industrial effluent which can cause severe health problems for public and environmental ecology. Therefore, this study aimed to remove MB from textile wastewater using the activated carbon developed from Rumexabyssinicus. The adsorbent was activated using chemical and thermal methods, and then it was characterized by SEM, FTIR, BET, XRD, and pH zero-point charge (pHpzc). The adsorption isotherm and kinetics were also investigated. The experimental design was composed of four factors at three levels (pH (3, 6, and 9), initial MB concentration (100, 150, and 200 mg/L), adsorbent dosage (20, 40, and 60 mg/100 mL), and contact time (20, 40, and 60 min)). The adsorption interaction was evaluated using response surface methodology. The characterization of a Rumexabyssinicus activated carbon was found to have multiple functional groups (FTIR), an amorphous structure (XRD), crack with ups and down morphology (SEM), pHpzc of 5.03 and a high BET-specific surface area of 2522 m2/g. The optimization of MB dye removal was carried out using the Response Surface methodology coupled with the Box Behnken approach. The maximum removal efficiency of 99.9% was recorded at optimum conditions of pH 9, MB concentration of 100 mg/L, the adsorbent dosage of 60 mg/100 mL, and contact time of 60 min. Among the three adsorption isotherm models, the Freundlich isotherm model was the best fit with an experimental value at R2 0.99 showing the adsorption process was heterogeneous and multilayer whereas the kinetics study revealed that pseudo-second-order at R2 0.88. Finally, this adsorption process is quite promising to be used at an industrial level.

Synthesis and characteristics of Ag/CuO nanomaterial

In this paper, Ag/CuO nanomaterials were successfully prepared by means of a hydrothermal method combined with chemical reduction. The synthesized Ag/CuO nanomaterials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), surface area analysis (BET). Two factors influencing the synthesis of materials such as time of chemical reduction, concentration of silver nitrate were studied. The results showed that silver crystals were introduced into the CuO nanosheets. The BET specific surface area of the obtained Ag/CuO nanomaterial is 113.47 m2.g-1. This nanomaterial has a high catalytic activity for the decomposition of methyl orange (MO) in the presence of hydrogen peroxide.

CoFe2O4@HaP as Magnetic Heterostructures for Sustainable Wastewater Treatment

The aim of this study was to synthesize a CoFe2O4@HaP nanocomposite (HaP-Hydroxyapatite) through the coprecipitation method in aqueous solution, with the purpose of using it in adsorption processes for the removal of Congo Red dye from aqueous solutions. Fourier Transform Infrared Spectroscopy (FT-IR) was used to characterize the synthesized material, identifying absorption bands specific to the functional groups of cobalt ferrite (Fe-O and Co-O at 603 and 472 cm-1) and hydroxyapatite PO43- at 1035, 962, 603 and 565 cm-1. Powder X-ray diffraction confirmed the cubic spinel structure of cobalt ferrite (S.G Fd-3m) and the hexagonal structure of hydroxyapatite (S.G P63/m). The nanocomposite's crystallite size was calculated to be 57.88 nm. Nitrogen adsorption/desorption isotherms and BET specific surface area measurements were used to monitor textural parameters, revealing an increase in specific BET surface area when cobalt ferrite nanoparticles (15 m2/g) were introduced into the hydroxyapatite heterostructure (34 m2/g). Magnetic properties were investigated by interpreting hysteresis curves in the ±10 kOe range, with the nanocomposite showing a saturation magnetization of 34.83 emu/g and a coercivity value of 0.03 kOe. The adsorption capacity of the CoFe2O4@HaP nanocomposite is up to 15.25 mg/g and the pseudo-second-order kinetic model (Type 1) fits the data with a high correlation coefficient of 0.9984, indicating that the chemical adsorption determines the rate-determining step of the process. The obtained nanocomposite is confirmed by the analyses, and the absorption measurements demonstrate that it can be utilized to degrade Congo Red dye.

Decrease in the Adsorption Capacity of Adsorbents in the High-Temperature Carbonate Loop Process for CO2 Capture

In this study, the sorption capacity of limestone samples for CO2 was investigated to determine the conditions under which they can be used in the high-temperature carbonate loop process. For the work, limestone samples from the Czech Republic were used, which contained a high proportion of CaO (more than 97 wt.%). A total of 20 cycles of calcination (950 °C) and subsequent CO2 sorption–carbonation (650 °C) were performed for each limestone sample tested. The sorption capacity towards CO2 in the 20th cycle was less than 10% of the value determined in the first carbonation cycle of the samples and the most significant decrease was observed between the first and second cycles. The highest sorption capacity was determined for the Branžovy sample, which captured 268 mL of CO2/per 1 g of sorbent by chemisorption. Only 15 mL of carbon dioxide per 1 g of sorbent was bound by physisorption. However, in repeated use, the Vitošov limestone had the highest sorption capacity for CO2. For all samples, the amount of carbon dioxide bound by physisorption was in the range of 4 to 10% of the amount bound by chemisorption. Due to sintering of the material, the BET specific surface area decreased by 95 to 96%.

Fabrication and characterization of supercapacitor comprising mango kernel derived electrode under different electrolyte system

AbstractIn this work, supercapacitor or ultra‐capacitor cells are composed of active carbon material (ACM) having BET specific surface area of 1133 m2 g−1. The ACM is prepared by carbonizing waste biomass (mango kernel) at 900°C. To develop high porosity in ACM, potassium hydroxide was used as an activating agent. Porous morphology of the synthesized ACM is explored through Scanning Electron Microcopy. Thereafter, two supercapacitor cells have been composed by using the mentioned ACM (electrode material) and KOH 6 M & NaOH 1 M (electrolytes). Applicability of the electrode material for supercapacitor has been tested electrochemically through the standard CV, EIS, and CD techniques. Observed capacitive assets from CV curve at 5 mV s−1was 151.5 F g−1(with KOH 6 M) and 133 F g−1(with NaOH 1 M). Experimentally obtained impedance data from EIS technique were compared and fitted theoretically by utilizing Randles fitting circuit. By taking frequency into consideration, it is found that the KOH 6 M based cell is providing lower time constant value and supporting better diffusion process than NaOH. Analysis of CD curve at 1.1 A g−1have given the capacitance of 136.5 F g−1and corresponding energy and power density of 12.1 Wh kg−1and 930 W kg−1. In addition to this, the small voltage drop and low ohmic resistance observed with KOH based system suggests its better capacitive assets than NaOH based supercapacitor system. Moreover, good capacitance retention of 85% is observed in a 2000 life cycle test.

Activated carbons with high micropore volume obtained from polyurethane foams for enhanced CO2 adsorption

Microporous activated carbons with remarkably high CO2 uptake have been synthesized using polyurethane (PU) commercial foams as precursors. The PU samples were pyrolyzed at different temperatures in N2 atmosphere and chemically activated with KOH. Adsorption isotherms at 0 °C and 25 °C and immersion calorimetry were applied to provide a deeper knowledge about the most relevant factors implied in CO2 capture process explaining, hence, the values of adsorption obtained. CO2 adsorption uptakes reached values of 7.4 mmol/g at 0 °C, 5.0 mmol/g at 25 °C and 2.7 mmol/g at 50 °C. The remarkably high values of CO2 uptake are closely related with the BET specific surface area of the carbon foams but also with the high volume of narrow micropores all the samples present a high volume of micropores (between 0.59 and 0.71 cm3/g) as also confirmed by immersion calorimetry.

From crystal phase mixture to pure metal-organic frameworks – Tuning pore and structure properties

In this study, a sonochemical route for the preparation of a new Hf-MIL-140A metal–organic framework from a mixture of UiO-66/MIL-140A is presented. The sonochemical synthesis route not only allows the phase-pure MIL-140A structure to be obtained but also induces structural defects in the MIL-140A structure. The synergic effect between the sonochemical irradiation and the presence of a highly acidic environment results in the generation of slit-like defects in the crystal structure, which increases specific surface area and pore volume. The BET-specific surface area in the case of sonochemically derived Zr-MIL-140A reaches 653.3 m2/g, which is 1.5 times higher than that obtained during conventional synthesis. The developed Hf-MIL-140A structure is isostructural to Zr-MIL-140A, which was confirmed by synchrotron X-ray powder diffraction (SR-XRD) and by continuous rotation electron diffraction (cRED) analysis. The obtained MOF materials have high thermal and chemical stability, which makes them promising candidates for applications such as gas adsorption, radioactive waste removal, catalysis, and drug delivery.

An investigation of the influence of nanofibers morphology on the performance of QCM-based ethanol vapor sensor utilizing polyvinylpyrrolidone nanofibers active layer

Quartz crystal microbalances (QCMs) coated by polyvinylpyrrolidone (PVP) nanofibers with controlled morphology have been made for ethanol vapor detection. We used electrospinning to deposit PVP nanofibers of different morphologies (spherical-beaded, spindle-beaded, and pure nanofiber) on a QCM surface to study the effect on sensor performance. BET characterization revealed that the spherical-beaded nanofiber had the highest BET-specific surface area than the other morphologies, which improves the QCM sensor sensitivity, limit of quantification (LOQ), limit of detection (LOD), and sensor response. QCM coated with spherical-beaded nanofiber showed improved sensitivity of 2.632 Hz/ppm, lower LOD and LOQ of 0.018 ppm and 0.061 ppm, and better response compared to those coated with spindle-beaded and pure nanofiber. Based on adsorption isotherm models, Freundlich adsorption isotherm was found to be the most suitable for describing ethanol vapor adsorption on the sensor. The high sensitivity of the sensor to ethanol vapor was attributed to hydrogen bonding interactions between the sensor and the ethanol molecules. This study shows that the QCM-based sensor performance can be improved by modifying the morphology of nanofibrous coating layer.

Mesoporous Zr-G-C3N4 Sorbent as an Exceptional Cu (II) Ion Adsorbent in Aquatic Solution: Equilibrium, Kinetics, and Mechanisms Study

A mesoporous Zr-G-C3N4 nanomaterial was synthesized by a succinct-step ultrasonication technique and used for Cu2+ ion uptake in the aqueous phase. The adsorption of Cu2+ was examined by varying the operating parameters, including the initial metal concentration, contact time, and pH value. Zr-G-C3N4 nanosorbent displays graphitic carbon nitride (g-C3N4) and ZrO2 peaks with a crystalline size of ~14 nm, as determined by XRD analysis. The Zr-G-C3N4 sorbent demonstrated a BET-specific surface area of 95.685 m2/g and a pore volume of 2.16 × 10−7 m3·g−1. Batch mode tests revealed that removing Cu (II) ions by the mesoporous Zr-G-C3N4 was pH-dependent, with maximal removal achieved at pH = 5. The adsorptive Cu2+ ion process by the mesoporous nanomaterial surface is well described by the Langmuir isotherm and pseudo-second-order kinetics model. The maximum adsorption capacity of the nanocomposite was determined to be 2.262 mol·kg−1 for a contact time of 48 min. The results confirmed that the fabricated mesoporous Zr-G-C3N4 nanomaterial is effective and regenerable for removing Cu2+ and could be a potent adsorbent of heavy metals from aqueous systems.

Facile synthesis of MOF-5-derived porous carbon with adjustable pore size for CO2 capture

In this study, a facile strategy is reported for the preparation of porous carbon materials with adjustable pore size through carbonization of MOF-5 at 900 ​°C with the assistance of different additives. Results show that the physical and chemical properties (such as morphology, carbon defect content, BET specific surface area, pore structure) of the porous carbon materials can be adjusted through introduction of different compounds (i.e., C16H32O2, C6H14O6, C18H36O2, Na2CO3, KOH, Cu(NO3)2, NaCl, KCl, MgCl2, ethyl cellulose) during the carbonization processes. CO2 adsorption experiment results show that there is a linear relationship between the CO2 adsorption capacity (at 25 ​°C and 0.15 ​bar) and the cumulative pore volume of pores at 5–7 ​Å, suggesting that pores in the range of 5–7 ​Å play a major role in CO2 adsorption at such condition. While the CO2 adsorption capacity (at 25 ​°C and 0.15 ​bar) is independent on the BET specific surface area of the materials. Among the prepared porous carbon materials, 5C–C6H14O6-900 exhibits the highest CO2 adsorption capacity (i.e., 3.32 ​mmol/g at 25 ​°C and 1 ​bar, 0.88 ​mmol/g at 25 ​°C and 0.15 ​bar), with good adsorption/desorption cycle stability and CO2/N2 selectivity. Our work provides a facile and general method to adjust and control the pore size distribution of MOF-derived porous carbon materials. Besides, the analysis results indicate that the micropores in a specific pore size range play a decisive role in the adsorption of CO2 at low pressure, which provides a new idea for the preparation of high-efficiency adsorbents at low pressures.

Organic solvent reverse osmosis characteristics of TiO2-ZrO2-organic chelating ligand (OCL) composite membranes using OCLs with different molecular sizes

In this study, organic chelating ligand (OCL) composite membranes (TiO2-ZrO2-OCL) were fabricated for application to organic solvent reverse osmosis (OSRO). Although it is difficult to control the pore structures of TiO2 and ZrO2 at the RO level, we attempted to control the dense pore structure of the TiO2-ZrO2-OCL membranes by using three different molecular sizes of OCLs: Acetylacetone (ACA), Methyl-2,4-heptanedione (ACAiB), and 2,6-Dimethyl-3,5-heptanedione (ACA2iP). The bonding state, amorphous structure, and pore structure of TiO2-ZrO2-OCL powder samples were investigated. Pair distribution function (PDF) analysis of TiO2-ZrO2-OCL powders suggested that the TiO2-ZrO2 network was changed with the molecular sizes of the OCLs. Nitrogen adsorption isotherms showed that OCLs with a larger molecular size had a larger BET specific surface area. TiO2-ZrO2-ACAiB and TiO2-ZrO2-ACA2iP membranes exhibited excellent methanol selective permeability for methanol (90 wt%) and toluene (10 wt%) at a transmembrane pressure of 5 MPa, and OSRO membranes with total flux that ranged from 0.072 to 0.968 kg m-2h−1 were fabricated with separation factors that ranged from 3.2 to 180. The molecular weight cut-off (MWCO) of TiO2-ZrO2-OCL membranes was evaluated based on the rejection of ethanol or isopropyl alcohol in methanol and methyl orange in methanol, and it was ranged from 80 to 200 g/mol. In addition, TiO2-ZrO2-OCL membranes showed high selectivity at low pressure with relatively low levels of methanol flux.

Synthesis and characterization of Sr2+ and Gd3+ doped magnetite nanoparticles for magnetic hyperthermia and drug delivery application

Commendable efforts have been gingered towards the fight against cancer. Nevertheless, it remains a major public health concern due to its predominant cause of death globally. Given this, we synthesized two different nanoparticles, Sr2+ and Gd3+ doped magnetite for magnetic hyperthermia and drug delivery application. Based on the characterization, the diffractogram shows that only one phase related to magnetite with a crystallite size of 10 nm was formed. TEM images revealed nanoparticles of spherical shapes of approximately 12 nm. There is no difference in magnetic saturation of the as-received synthesized samples (Fe3O4@Sr and Fe3O4@Gd), while the BET-specific surface area of Fe3O4@Gd is 8 m2 g−1 higher than Fe3O4@Sr. The heat generation in alternating magnetic field (the magnetic hyperthermia) of Fe3O4@Sr functionalized with citric acid and loaded with 5- fluorouracil (Fe3O4@Sr@CA@5-flu) is slower than Fe3O4@Gd@CA@5-flu. The specific absorption rate (SAR) of Fe3O4@Gd@CA@5-flu, 112.0 ± 10.4 W g−1 was found to be higher than that of Fe3O4@Sr@CA@5-flu. The thermogram shows that 11% of the drug was successfully loaded on Fe3O4@Gd@CA@5-flu. The release of the antitumor drug by the synthesized nanoparticle drug carriers for ovarian cancer (SKOV-3 cells) therapy showed that more than 50% of the cancer cell’s viability was reduced after 72 h of incubation. The synthesized nanoparticles demonstrated a promising drug carrier for the treatment of SKOV-3 cells.

Polyimide and polystyrene‐based activated carbon nanofibers with tubular structure for supercapacitor

AbstractPolyimide (PI) and polystyrene (PS) blend electrospun fibers are prepared by electrospinning method. PI and PS are not completely compatible due to the difference of solubility and surface energy in electrospinning precursor, so PI/PS electrospun fibers have some phase separations along the electric field direction under the high‐voltage electrostatic force. PI with high carbon conversion served as carbon nanofibers, PS with low carbon conversion served as porogenic sacrificial agent, so PI/PS‐based activated carbon nanofibers derived from PI/PS electrospun fibers with well‐controlled opening tubular structure are obtained via thermally induced phase separation process. The morphology and electrochemical performance of activated carbon nanofibers are investigated by structural analysis and electrochemical measurements. The relationships among pores structure, electrolyte character and electrochemical performance of activated carbon fibers are extensively evaluated. Activated carbon nanofibers derived from PI/PS (mass ratio = 1:2) electrospun fibers with nano scale opening tube wall structure show a small charge transfer resistance and the short electric double layers forming time, but also suitable average pore diameter (3.74 nm), high BET specific surface area (952.5 m2 g−1) and average pore volume (0.532 cm3 g−1). Then, a comprehensive electrochemical performance can also be achieved in organic electrolyte: high energy density (31.80 Wh kg−1), good power density (3094.05 W kg−1) and low internal resistance (1.24 Ω). The findings reveal a guideline for the preparation of polymer‐based hierachical porous and opening tubular structure activated carbon nanofibers for electrochemical energy conversion and storage devices.

Aerogels based on cationically modified chitosan and poly(vinyl alcohol) for efficient capturing of viruses

In this study, we developed a new filtering bioaerogel based on linear polyvinyl alcohol (PVA) and the cationic derivative of chitosan (N-[(2-hydroxy-3-trimethylamine) propyl] chitosan chloride, HTCC) with a potential antiviral application. A strong intermolecular network architecture was formed thanks to the introduction of linear PVA chains, which can efficiently interpenetrate the glutaraldehyde(GA)-crosslinked HTCC chains. The morphology of the obtained structures was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The aerogels and modified polymers' elemental composition (including the chemical environment) was determined using X-ray photoelectron spectroscopy (XPS). New aerogels with more than twice as much developed micro- and mesopore space and BET-specific surface area were obtained concerning the starting sample chitosan aerogel crosslinked by glutaraldehyde (Chit/GA). The results obtained from the XPS analysis showed the presence of cationic 3-trimethylammonium groups on the surface of the aerogel, which can interact with viral capsid proteins. No cytotoxic effect of HTCC/GA/PVA aerogel was also observed on fibroblast cells of the NIH3T3 line. Furthermore, the HTCC/GA/PVA aerogel has been shown that efficiently traps mouse hepatitis virus (MHV) from suspension. The presented concept of aerogel filters for virus capture based on modified chitosan and polyvinyl alcohol has a high application potential.

Electronic Modulation of the 3D Architectured Ni/Fe Oxyhydroxide Anchored N-Doped Carbon Aerogel with Much Improved OER Activity.

It remains a big challenge to develop non-precious metal catalysts for oxygen evolution reaction (OER) in energy storage and conversion systems. Herein, a facile and cost-effective strategy is employed to in situ prepare the Ni/Fe oxyhydroxide anchored on nitrogen-doped carbon aerogel (NiFeOx(OH)y@NCA) for OER electrocatalysis. The as-prepared electrocatalyst displays a typical aerogel porous structure composed of interconnected nanoparticles with a large BET specific surface area of 231.16 m2·g-1. In addition, the resulting NiFeOx(OH)y@NCA exhibits excellent OER performance with a low overpotential of 304 mV at 10 mA·cm-2, a small Tafel slope of 72 mV·dec-1, and excellent stability after 2000 CV cycles, which is superior to the commercial RuO2 catalyst. The much enhanced OER performance is mainly derived from the abundant active sites, the high electrical conductivity of the Ni/Fe oxyhydroxide, and the efficient electronic transfer of the NCA structure. Density functional theory (DFT) calculations reveal that the introduction of the NCA regulates the surface electronic structure of Ni/Fe oxyhydroxide and increases the binding energy of intermediates as indicated by the d-band center theory. This work provides a new method for the construction of advanced aerogel-based materials for energy conversion and storage.