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The removal of Ni2+ from aqueous solution by magnetic multiwalled carbon nanotube nanocomposite (MMWCNTs-C) was investigated. MMWCNTs-C was characterized by X-ray Diffraction method (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), surface area (BET), and Fourier Transform-Infrared Spectroscopy (FTIR). The effects of initial concentration, contact time, solution pH, and temperature on the Ni2+ adsorption onto MMWCNTs-C were studied. The Langmuir and Freundlich isotherm models were applied to fit the adsorption data. The results showed that the adsorption isotherm data were fitted well to the Langmuir isotherm model with the maximum monolayer adsorption capacity of 2.11 mg g–1. The adsorption kinetics was best described by the pseudo-second-order model. The thermodynamic parameters, such as ΔHo, ΔGo and ΔSo, were also determined and evaluated. The adsorption of Ni2+ is generally spontaneous and thermodynamically favorable. The values of ΔHo and ΔGo indicate that the adsorption of Ni2+ onto MMWCNTs-C was a physisorption process.

The combination of fumed silica (SiO2) with carbon black (CB) for improving thermal stability, flame retardancy and mechanical properties of linear low density polyethylene (LLDPE) was investigated. The temperature at the maximum weight loss rate of LLDPE was dramatically increased by 92 degrees C, and the peak value of heat release rate measured by cone calorimeter was significantly reduced by 80.7%. The improved thermal stability and flame retardancy of LLDPE were partially attributed to the formation of a percolated network structure in LLDPE matrix, and partially to the accelerated oxidation crosslinking reaction of LLDPE or other radicals by CB and SiO2. More importantly, although both SiO2 and CB were used without any pre-treatment, ternary LLDPE nanocomposites showed much higher mechanical properties compared to those of neat LLDPE. This was ascribed to good dispersions of two kinds of nanoparticles and strorig matrix-nanoparticle interfacial interactions with LLDPE matrix. (C) 2014 Elsevier Ltd. All rights reserved.

A novel combined catalyst of fumed silica (SiO 2 ) with Ni 2 O 3 was demonstrated to be more efficient than SiO 2 or Ni 2 O 3 alone in enhancing the char yield of poly(lactic acid) (PLA) and improving its char layer structure, which greatly enhanced the flame retardancy of PLA. The results of field-emission scanning electron microscope, transmission electron microscope, X-ray diffraction, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed that the residual chars mainly consisted of block-like carbon and carbon nanotubes with some surface functional groups. The flame retardancy of PLA and its composites was studied by cone calorimeter test. The heat release rate and total heat release of PLA composites containing both SiO 2 and Ni 2 O 3 decreased significantly in comparison with those of neat PLA. The investigation of the synergetic mechanism showed that in the presence of both SiO 2 and Ni 2 O 3 , a large amount of chars were in situ formed from the catalytic carbonization of degradation products of PLA by Ni 2 O 3 during combustion. This not only reduced the release of flammable degradation products, but also acted as an insulating barrier to prohibit the oxygen and feedback of heat from reaching the underlying substrate. On the other hand, the formation of a percolated network structure of SiO 2 and Ni 2 O 3 particles in PLA matrix increased the melt viscosity of PLA and facilitated the formation of a more compacted protective layer, which promoted the flame retardancy of PLA.

Upcycling waste plastics into high value-added carbon nanomaterials has been a hot topic due to everincreasing generation of waste plastics, however, little attention has been paid to valuable hollow carbon spheres (HCSs). Herein, uniform mesoporous HCSs with controllable diameter and high surface area were efficiently prepared through the carbonization of mixed plastics consisting of polypropylene, polyethylene and polystyrene under the combined catalysis of organically-modified montmorillonite (OMMT)/Co3O4 at 700 degrees C. The morphology, microstructure, phase structure, textural property, surface element composition and thermal stability of HCSs were investigated by Scanning electron microscope, transmission electron microscope (TEM), high-resolution TEM, X-ray diffraction, Raman spectroscopy, N-2 sorption, X-ray photoelectron spectroscopy and thermal gravimetric analysis. The effects of OMMT on the dispersion of Co3O4 in the mixed plastics and the degradation of mixed plastics were studied. It was found that OMMT not only promoted the dispersion of Co3O4 in the mixed plastics, which favored to control the diameter of HCSs, but also promoted the degradation of mixed plastics into light hydrocarbons and aromatics, which facilitated the growth of HCSs. Finally, a possible mechanism was proposed to explain the growth of uniform HCSs with controllable diameter. This facile method provides a novel potential way to convert waste plastics into valuable HCSs, which can be used as catalyst support, adsorbent, storage medium and template for the synthesis of other useful hollow materials, etc. (C) 2014 Elsevier B.V. All rights reserved.

A one-pot approach was used to convert polyethylene (PE) with different chain structures into carbon nanomaterials (CNMs) under the combined catalysis of CuBr and NiO at 700 °C, including linear low density polyethylene (LLDPE), low density polyethylene (LDPE) and high density polyethylene (HDPE). The effect of chain structure of PE on the yield, morphology, microstructure, phase structure and thermal stability of CNMs, including cup-stacked carbon nanotubes (CS-CNTs) and carbon nanofibers (CNFs), were investigated by scanning electron microscope, transmission electron microscope (TEM), high-resolution TEM, X-ray diffraction, Raman spectroscopy and thermal gravimetric analysis. In addition, the degradation products from different chain structures of PE under the catalysis of CuBr were analyzed by gas chromatography and gas chromatography–mass spectrometry. It was demonstrated that the branched structure played an important effect in the degradation products of PE. The dehydrogenation and aromatization of LLDPE were remarkably promoted by Br radicals from the decomposition of CuBr to form a large amount of light hydrocarbons and a relatively small amount of aromatics, favoring the formation of long and straight CS-CNTs. However, the degradation of LDPE was not obviously influenced by Br radicals due to its high extent of branched structure, while the random cleavage of HDPE was accelerated with the formation of a lot of olefins with long chains, resulting in the formation of short and winding CNFs. This work will contribute to the conversion of mixed waste polyolefin into high value-added CNMs.

Recently, upcycling waste plastics into high-value-added carbon nanomaterials has attracted much attention; however, few studies have focused on the conversion of waste plastics into graphene with high yield. Herein, we report a simple novel method to synthesize graphene flakes (GFs) with high yield through catalytic carbonization of waste polypropylene (PP) using organically modified montmorillonite (OMMT) as degradation catalyst and template at 700 °C. The yield, morphology, microstructure, phase structure, thermal stability, and surface element composition of GFs were investigated. In addition, it was found that OMMT not only promoted the degradation of waste PP into light hydrocarbons and aromatics but also acted as template and catalyzed carbonization of the light hydrocarbons and aromatics into GFs. At last, a possible mechanism for the formation of GFs was put forward. This simple approach provides a novel way to effectively prepare high-value-added GFs using waste plastics as carbon sources.

Much attention has been paid to the synthesis of core/shell metal@carbon composites, but many of the proposed methods are limited by sophisticated procedure and expensive precursors. Herein, a facile one-pot approach is established to prepare magnetic core/shell Co@C spheres through catalytic carbonization of mixed plastics (consisting of polypropylene, polyethylene and polystyrene) by Co3O4 at 700 °C. The yield, composition, morphology, phase structure, textural property, surface element composition, thermal stability and magnetic property of core/shell Co@C spheres are investigated. The core/shell Co@C spheres have a distinct ordered and curved graphitic structure, and their main diameters are in the range of 110–130 nm. Besides, they show a ferromagnetic behavior with high saturation magnetization (85.6–101.6 emu g−1). Furthermore, it was observed that Co3O4 was uniformly distributed in mixed plastics and formed a network structure, which provided a precondition for the carbonization of mixed plastics into core/shell Co@C spheres with uniform sizes. Finally, the core/shell Co@C spheres were found to show high performance in photo-degradation of Congo red (CR) with good recyclablity, reusability and long-term stability. It was demonstrated that the outer carbon shell promoted the degradation of CR and served as a protective layer for cobalt core to improve acid resistance, while the inner cobalt core accelerated the decomposition of H2O2 into radicals, which catalyzed the degradation of CR. More importantly, this simple approach offers a potential way to prepare magnetic core/shell metal@carbon composites from cheap waste plastics.

Recently, there has been intense interest in the conversion of plastics into high value-added carbon nanomaterials (CNMs), however, the effect of catalyst diameter on the formation of CNMs is still ambiguous. Herein, uniform NiO catalysts with different diameter (18–227 nm) were firstly prepared by a sol–gel combustion synthesis method and calcination at different temperatures. Subsequently, the combined organically-modified montmorillonite (OMMT)/NiO catalyst was used to catalyze carbonization of polypropylene (PP, selected as an example of plastics) into CNMs at 700 °C. The effect of NiO catalyst diameter on the yield, morphology, microstructure, phase structure, thermal stability and texture properties of CNMs including sponge-like cup-stacked carbon nanotubes (CS-CNTs) and carbon fibers were investigated by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction, Raman spectroscopy, thermal gravimetric analysis and N2 sorption. Besides, the effects of NiO catalyst diameter on the coalescence and reconstruction of NiO particles were explored. It was demonstrated that NiO catalysts with small diameter were more susceptible to coalescence and reconstruction into rhombic shape, which facilitated the growth of long, straight CS-CNTs. Finally, the obtained sponge-like CS-CNTs were found to show high performance in the adsorption of diesel, vegetable oil, kerosene and mineral oil with good recycling performance. It is believed that this work will contribute to the conversion of waste plastics into high value-added CNMs.

A novel combined catalyst of activated carbon (AC) with Ni2O3 was demonstrated to be much more efficient than AC or Ni2O3 alone in enhancing the char yield of polypropylene (PP) and improving its char layer structure, which greatly improved the thermal stability and flame retardancy of PP. The results of Xray diffraction, field-emission scanning electron microscope and transmission electron microscope revealed that the residual char mainly consisted of carbon nanotubes (CNTs). Thermal gravimetric analyses results indicated that the combination of AC and Ni2O3 dramatically enhanced the thermal stability of PP. The flame retardancy of PP and its composites was studied by cone calorimeter test. The heat release rate and total heat release of the ternary PP/7.5AC-7.5Ni(2)O(3) composite decreased significantly in comparison with those of neat PP. The investigation of the synergetic mechanism showed that in the presence of both AC and Ni2O3, a large amount of CNTs were in situ formed from the degradation products of PP during combustion. This not only reduced the release of flammable degradation products of PP, but also acted as a thermal shield for energy feedback from the flame. In addition, the formation of a network-like structure of AC and Ni2O3 particles in PP matrix favored the formation of a more compacted protective layer, which enhanced the flame retardancy of PP. (C) 2013 Elsevier Ltd. All rights reserved.

Correction for ‘Simultaneously improving the thermal stability, flame retardancy and mechanical properties of polyethylene by the combination of graphene with carbon black’ by Jiang Gong et al., RSC Adv., 2014, 4, 33776–33784.

In this study, magnetic Fe@graphite nanocomposite (Fe@G-N) with a core-shell structure was prepared by chemical vapor deposition CVD process for the adsorptive removal of anionic dyes from aqueous solutions. Fe@G-N was characterized by XRD, HRTEM, HAADF-STEM, FTIR, Raman spectroscopy, BET and zeta potential measurements, and then applied in adsorption of two kinds of anionic dyes, Acid Red 88 (AR88) and Direct Orange 26 (DO26). The effect of parameters like initial dye concentration (5-40mgL-1), pH solution (4-10) and temperature (20-60°C) on the adsorption process was studied. The pseudo-first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data. A kinetic study indicated that a pseudo-second-order model agreed well with the experimental data. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Adsorption equilibrium studies showed that adsorption of AR88 and DO26 followed the Langmuir model. Thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were also obtained and analyzed.

Porous Pd@m-C/SiO2 nanopeapods are prepared by a nanoconfinement method. The Pd nanoparticles show high efficiency and stability in chemical reactions such as reduction of nitrobenzene by H2 and reduction of NO by NH3. The high catalytic activity is attributed to the unique peapod structure, mesoporous wall, and large specific surface area on Pd@m-C/SiO2 rendering the Pd nanoparticles highly active in chemical reactions.

Spherical photocatalyst based on ordered mesoporous carbon and graphitic carbon nitride with core/shell structure (CS/GCN) was successfully synthesized via facile electrostatic self-assembly strategy. The photocatalytic properties of the hybrid were evaluated by the decomposition of Acid Red 18 under simulated solar light irradiation in comparison to the bulk graphitic carbon nitride (GCN). The results clearly revealed that coupling of carbon nitride with mesoporous carbon allows the catalyst to form with superior photocatalytic performance. The photoactivity of CS/GCN was over nine times higher than that of pristine GCN. Introducing mesoporous carbon into GCN induced higher surface area of the heterojunction and also facilitated the contact surface between the two phases. The synergistic effect between those two components enhanced the visible light-harvesting efficiency and improved photoinduced charge carrier generation, and consequently their proper separation. The electrochemical behavior of the obtained composite was also evaluated by electrochemical impedance, transient photocurrent response and linear sweep potentiometry measurements. The results confirmed that transport and separation of charge carriers in the hybrid was enhanced in comparison to the reference bulk graphitic carbon nitride. Detailed electrochemical, photoluminescence and radical scavenger tests enabled determination of the possible mechanism of photocatalytic process. This work presents new insights to design a core/shell hybrid through the simple preparation process, which can be successfully used as an efficient photocatalyst for the treatment of wastewater containing dyes under solar light irradiation.

It is a great challenge to improve the flame retardancy of polymer materials by adding eco-friendly magnesium hydroxide (Mg(OH)2) but simultaneously maintain satisfied mechanical performances. In this study, expanded graphite (EG) as a synergist was introduced into poly(butylene succinate) (PBS)/Mg(OH)2 system to investigate the effect of EG on their flame retardancy, thermal stability and mechanical properties. The results showed that only addition of 5 wt% EG into PBS/20 wt%Mg(OH)2 resulted in excellent flame retardancy, including that the LOI was 29.4%, the UL-94 rating reached to V0, and the PHRR decreased by 73%. These flame retarded parameters were comparable or even better than that of PBS/40 wt%Mg(OH)2 composites. More importantly, PBS/20 Mg(OH)2/5 EG presented much better thermal stability and mechanical properties than PBS/40 wt%Mg(OH)2, indicating a balanced improvement on comprehensive performances of PBS. Based on the comparison with PBS/20 Mg(OH)2/5Graphene(Gr) system and the structure analysis for residual chars, the mechanism for improved flame retardancy was attributed to the formation of gradient-structured char layer due to the helpful thermal expansion process of EG together with the decomposition of Mg(OH)2 during combustion, resulting in better barrier action to heat, oxygen and flammable gases via “labyrinth effect”. As far as we know, it is the first report that gradient-structured char layer was discussed in flame retarded polymer systems. Hence, this work provides not only a high-efficient synergist to improve the flame retardant efficiency of Mg(OH)2, but also useful guidelines to design polymer composites with balanced comprehensive performances.

Graphitic carbon nitride (gCN) exhibits outstanding photocatalytic performances toward H2 evolution. However, it can be further improved by overcoming its disadvantages such fast recombination of pohotogenerated electron-hole pairs. Here, we propose an efficient photocatalysts based on three components: (i) gCN modified with (ii) cadmium compounds (CdX: Cd(OH)2, CdS, CdO) and (iii) nanoporous carbon flakes (NPC) derived from Al-metal organic framework. The fabrication method was focused on finding the optimal hybrid composition dispalying the most powerful performance. Three main aspects were revealed: (i) band gap of gCN narrowing from 2.70 eV to 2.32 eV, (ii) reduction of overpotential for H2 evolution, as conduction band minimum (CBM) moved from −1.07 V vs. NHE to −0.63 V vs. NHE and (iii) enhanced charge separation, since CdX and NPC acted as electron acceptors. These factors had an effect on ˜60-fold enhancement of the photocatalytic efficiency. The mechanism of the photocatalytic process was discussed.

Recently it is a hot topic to fabricate high-performance polymer composites via combination strategy. Herein the combination of nanoscale carbon black (CB) and ammonium polyphosphate (APP) into polypropylene (PP) was efficient to remarkably improve its thermal stability and flame retardancy. The optimal ratio corresponding to 7 wt% CB and 18 wt% APP (7CB18APP), presented the increase on Tmax (the temperature at the maximum weight loss rate) by 138.7 °C under air. Moreover, its LOI (limited oxygen index) reached to 29.8%, and it passed V0 rating at UL-94 (vertical burning test). According to cone calorimeter testing results, it exhibited a decrease on PHRR (peak value of heat release rate) and THR (total heat release) by 75% and 42%, respectively. Based on the analysis for microstructure and mechanical strength of chars as well as rheological behavior, a reactive crosslinking network between CB and APP was confirmed during combustion, which was favorable to the formation of continuous and compact carbon layer in condensed phase. In addition, the “trapping radicals” effect from CB and APP derivatives might also helpful to the improvement on thermal stability and flame retardancy in gas phase.

Great efforts have been devoted to designing porous carbons to improve energy density of supercapacitor, yet still impeded by high-cost and time-consuming procedures. The low capacitance and poor rate capability of various biomass-derived carbons in organic electrolyte remain a challenge for their practical application. Herein, to address these issues, biomass (leek) is used to produce three-dimensional (3D) porous carbon, which possesses big cavities, high specific surface area and well-defined hierarchical pores. In three-electrode system, it exhibits a high capacitance of 349 F g−1 at 0.5 A g−1 in 6 M KOH electrolyte and a superior cycling stability of no capacitance decay at 20 A g−1 over 10,000 cycles. Notably, the assembled symmetric cell reveals a high capacitance of 191 F g−1 at 0.5 A g−1 with a good rate capability (77% capacitance retention at 10 A g−1) in organic electrolyte. In addition, a high energy density of 86 Wh kg−1 at the power density of 450 W kg−1 is demonstrated, while it remains 55 Wh kg−1 at a high power density of 18 kW kg−1, superior to that of many biomass-derived carbon materials. The excellent electrochemical performance offers great potential as next-generation electrode material for supercapacitor.

Although metal-organic frameworks (MOF) derived porous carbon has been widely used as electrode materials for supercapacitor, its limited ion diffusion/transportation as well as relatively low conductivity have hampered high capacitance achieved. To address this issue, an interconnected hierarchical nitrogen doped nanoporous carbon structure (N-NPC) from nanosized MOF crystals is proposed, which presents high ion-accessible surface area and ion diffusion/transportation rate as well as enhanced electric conductivity. Benefiting from the interconnected structure, the N-NPC exhibits an ultrahigh capacitance of 479 F g−1 in an aqueous electrolyte and 391 F g−1 in an organic electrolyte. More importantly, the energy densities are 22.9 Wh kg−1 and 100.6 Wh kg−1 in the aqueous and organic electrolytes, and excellent long-term cycle stability are achieved, respectively.

Carbon-based supercapacitors have attracted considerable academic and practical interest due to their advantages of low cost, high power density, and superior durability. Herein, we report the facile synthesis of hierarchical porous carbon sheets (HPCSs) featuring a high specific surface area (2788 m2 g-1), derived from pyrrole through a combination of MgO template carbonization and KOH activation. The hierarchical pores with the co-existence of micropores and mesopores were obtained in the HPCSs. Benefiting from the high surface area, well-balanced pore size distribution as well as high conductivity, the prepared HPCSs exhibited a high gravimetric specific capacitance of 226.4 F g-1 at a scan rate of 1 mV s-1 in the electrolyte of 1 M H2SO4 in the two-electrode configuration. Moreover, the excellent electrochemical long-cycle stability has been demonstrated by 10 000 cycles of rapid charging-discharging at 10 A g-1 with a capacitance retention of 97.3%. The electrochemical performance clearly indicates the promising potential of using HPCSs as electrode materials for supercapacitors.

A novel in situ synthesis of Pd nanoparticles supported in hollow carbon spheres (HCS) is reported. The size of the nanoparticles can be tuned via application of different Pd precursors. The hydrogen storage properties of Pd supported in HCS under room temperature were examined at partial pressures. We observed significant difference between the storage capacities of two samples containing Pd nanoparticles with different diameter distributions. The results showed that the sample with suitable diameters of Pd nanoparticles was more favorable for the H2 storage, even lower mass of Pd was used. The maximum hydrogen storage of 0.36 wt % exhibited the sample with Pd nanoparticles with the diameter of 11 nm (measured at 298 K and 24 bar) and it was enhanced by the factor of two in respect to the pristine HCS. The enhanced storage capacity is due to cumulative hydrogen adsorption by HCS and Pd nanoparticles. We also propose the mechanism of hydrogen storage in our material.

A one-pot approach was established to effectively convert polypropylene (PP) and linear low density polyethylene (LLDPE) into carbon nanomaterials (CNMs) including cup-stacked carbon nanotubes and carbon nanofibers under the combined catalysis of HZSM-5/NiO or HZSM-5/Ni2O3 at 700 degrees C. The effects of HZSM-5 content, a nickel catalyst, and the carbon precursor on the morphology, microstructure, phase structure, and thermal stability of CNMs were investigated with scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction, Raman spectroscopy, and thermal gravimetric analysis. The effect of HZSM-5 content on the degradation products of PP and LLDPE was analyzed by gas chromatography and gas chromatography mass spectrometry. With increasing HZSM-5 content, the yields of light hydrocarbons and aromatics increased due to proton acid sites on the surface of HZSM-5 catalyzing cracking of PP or LLDPE degradation products. This one-pot approach provides a novel potential way to largely transform mixed waste polyolefin into high value-added CNMs.

Magnetic multi-walled carbon nanotubes-Fe3C nanocomposite was synthesized by chemical vapor deposition process and was used as an adsorbent for the removal of acid dye Acid Red 88 (AR88) from aqueous solution. The effects of various parameters such as initial AR88 concentration (10–58 mg L−1), pH (3.1–11.3) and temperature (20–60°C) were investigated. The properties of this adsorbent were characterized by X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray analysis, fourier transform IR, N2 adsorption/desorption isotherms, and particle size distribution by laser diffraction. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Freundlich model. Kinetic adsorption data were analyzed using the Lagergren pseudo-first-order kinetic model, the pseudo-second-order model and the intraparticle diffusion model. The regression results showed that the adsorption kinetics was more accurately represented by pseudo-second-order model. Thermodynamics parameters, Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0), were calculated. All ΔG0 values were negative. The values of ΔH0 and ΔS0 were −4.70 and −7.98 J mol−1 K−1, respectively, indicating that adsorption of AR88 onto magnetic multi-walled carbon nanotubes nanocomposites was spontaneous and exothermic in nature.

Core-shell-structured mesoporous silica spheres were prepared by using n-octadecyltrimethoxysilane (C18TMS) as the surfactant. Hollow mesoporous carbon spheres with controllable diameters were fabricated from core-shell-structured mesoporous silica sphere templates by chemical vapor deposition (CVD). By controlling the thickness of the silica shell, hollow carbon spheres (HCSs) with different diameters can be obtained. The use of ethylene as the carbon precursor in the CVD process produces the materials in a single step without the need to remove the surfactant. The mechanism of formation and the role played by the surfactant, C18TMS, are investigated. The materials have large potential in double-layer supercapacitors, and their electrochemical properties were determined. HCSs with thicker mesoporous shells possess a larger surface area, which in turn increases their electrochemical capacitance. The samples prepared at a lower temperature also exhibit increased capacitance as a result of the Brunauer-Emmett-Teller (BET) area and larger pore size.

Mesoporous hollow carbon nanospheres (HCNs) were synthesized through the carbonization of polystyrene (PS) under the combined catalysis of organically-modified montmorillonite (OMMT)/cobalt catalyst at 700 degrees C. The morphology, microstructure, phase structure, textural property and surface composition of the obtained mesoporous HCNs were investigated by field-emission scanning electron microscope, transmission electron microscope (TEM), high-resolution TEM, X-ray diffraction, Raman spectroscopy, N-2 sorption and X-ray photoelectron spectroscopy. It was found that OMMT not only promoted the dispersion of cobalt catalyst in the PS matrix but also affected the degradation of PS into light hydrocarbons and aromatics. The lattice oxygen of the cobalt catalyst facilitated the decomposition of light hydrocarbons and aromatics into atomic carbon during the formation of the mesoporous HCNs. A possible mechanism was proposed to explain the growth of mesoporous HCNs through the carbonization of PS under the combined catalysis of OMMT/cobalt catalyst. More importantly, this approach also offers a new potential way to transform waste polymer materials into mesoporous HCNs, which may be used as catalyst supports, adsorbents, storage media and templates for the synthesis of other useful hollow materials. (c) 2013 Elsevier Inc. All rights reserved.

In this study, hollow mesoporous carbon nanospheres (HMCN) prepared from core–shell structured mesoporous silica sphere using chemical vapor deposition were used as a novel adsorbent for the investigation of the adsorption of two acid dyes: Acid Orange 8 (AO8) and Acid Red 88 (AR88) from aqueous solutions. The adsorbent was characterized by X-ray diffraction XRD, high-resolution transmission electron microscopy HRTEM, Raman spectroscopy, Fourier infrared spectroscopy FTIR, N2 adsorption/desorption isotherms and zeta potential measurements. The effects of initial dye concentration, pH and temperature on adsorption capacity were studied. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Langmuir model. The maximum adsorption capacities of AO8 and AR88 onto HMCN from the Langmuir isotherm model were 454.6 and 555.6 mg g−1, respectively. The contact time required to obtain the equilibrium of AO8 and AR88 was 90 and 110 min, respectively. Kinetic adsorption data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order kinetic model and the intraparticle diffusion model. The adsorption kinetics well fitted using a pseudo-second-order kinetic model. Thermodynamics parameters, ΔGO, ΔHO and ΔSO, were calculated, indicating that the adsorptions of AO8 and AR88 was spontaneous and exothermic in nature.

Graphical abstract: - Highlights: • Adsorption of methylene blue (MB) on graphene oxide (GO). • Characterization of graphene oxide–methylene blue nanocomposite (MB–GO). • Examination of MB–GO efficiency in singlet oxygen generation (SOG). • MB–GO performs higher SOG efficiency than pristine MB. - Abstract: Due to unique electronic, mechanical, optical and structural properties, graphene has shown promising applications in many fields, including biomedicine. One of them is noninvasive anticancer therapy – photodynamic therapy (PDT), where singlet oxygen (SO), generated under the irradiation of light with appropriate wavelengths, kills cancer cells. In this study, authors report graphene oxide (GO) noncovalent functionalization with methylene blue (MB). MB molecules underwent adsorption on the surface of GO. Detailed characterization of the obtained material was carried out with UV–vis spectroscopy, Raman spectroscopy, FT-IR spectroscopy, and confocal laser scanning microscopy. Furthermore, its performance in singlet oxygen generation (SOG) under irradiation of laser with excitation wavelengths of 785 nm was investigated. Interestingly, GO functionalized with MB (MB–GO) showed enhanced efficiency in singlet oxygen generation compared to pristine MB. The efficiency in SOG was detected by photobleaching of 9,10-anthracenediyl-bis(methylene)dimalonic acid (ABMDMA). These results indicate the material is promising in PDT anticancer therapy and further in vitro and in vivomore » studies are required.« less

Here, we have functionalized graphene oxide with anticancer drug methotrexate through amide bonding. A kinetics of the drug release from graphene oxide in physiological solution – phosphate buffered saline (PBS) containing different biocompatible polymers have been investigated. Dispersion of MTX-GO in poly sodium-4-styrene sulfonate and poly ethylene glycol resulted in increase of the release time. The material was characterized with transmission electron microscopy, atomic force microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and UV–vis spectroscopy. Furthermore, antineoplastic action against human breast adenocarcinoma cell line MCF7 of MTX-GO and empty graphene oxide was explored.

A novel method for the fabrication of core/shell structured mesoporous carbon spheres with solid shell using a template method has been presented. The unique molecular nanostructures are characterized by XRD, TEM, TGA, and nitrogen adsorption/desorption measurement. The formation mechanism of the mesostructured carbon spheres with a carbon shell is proposed according to the experimental results. Nanoconfinement effect, occurring in the core/shell structured template, is believed to play a key role in mediating the formation of these hierarchical carbon mesostructures, with SnO2 as a template and C2H4 as a carbon source of a mesoporous carbon core. This synthesis method is simple, straightforward, and suitable for the preparation of various nanostructures that are unique scaffolds in catalytic and electrochemical applications.

We propose the synthesis and characterization of colloidal aluminium selenide nanocrystals using trioctylphosphine as a solvent. The nanoparticles have several absorption bands in the spectral region 330–410 nm and are bright UV-blue luminescent, which is well demanded in light collecting and emitting devices, e.g. for tuning their spectral characteristics to higher energy solar photons.

A one-pot method was used to prepare magnetic Ni/carbon (Ni/C) nanomaterials by catalytic carbonization of linear low density polyethylene (LLDPE) under the combined catalysis of Ni2O3 and polyvinyl chloride (PVC) resin. The yield of Ni/C nanomaterials was determined by the pyrolysis temperature, the type and the content of PVC resin. The yield of magnetic Ni/C nanomaterials first increased and then decreased with increasing PVC content. The obtained carbon nanomaterials mainly consisted of long carbon nanotubes (CNTs) at lower PVC content but short carbon nanofibers and amorphous carbon at higher PVC content. This is attributed to chlorine radicals from the decomposition of PVC resin promoting the dehydrogenation and aromatization of LLDPE macroradical fragments. The obtained magnetic Ni/C nanomaterials were used as adsorbents for the removal of methylene blue (MB) from water and showed an adsorption capacity as high as 165.5–175.2 mg/g, indicating the resultant magnetic Ni/C nanomaterials had potential application in wastewater treatment.

Promoted nanocrystalline iron was carburized in a differential tubular flow reactor with thermogravimetric measurement of mass changes. The carburization process was carried out in the presence of pure methane under atmospheric pressure at 650 °C to obtain different carburization degrees of the sample. The carburized iron samples were characterized by the X-ray diffraction, high-resolution transmission electron microscope in the energy-dispersive X-ray spectroscopy mode, thermoprogrammable oxidation, and Raman spectroscopy. As a result of the methane decomposition on the nanocrystalline iron the following nanocrystalline products were observed: iron carbide Fe3C, graphite, iron and nanotubes. The crystallinity of the samples increased with the carburization degree.

A one-pot approach was established to prepare carbon nanotubes (CNTs) through the carbonization of polypropylene (PP) by the combined catalysts of activated carbon (AC) with Ni 2 O 3 . The combination of AC with Ni 2 O 3 showed a synergistic catalysis on the catalytic conversion of PP to form CNTs. The effects of the content of AC and carbonization temperature on the yield of CNTs were studied. The morphology, phase structure and thermal stability of the obtained CNTs were analyzed by means of SEM, TEM, XRD, TGA and Raman. In this synergistic catalysis, the surface functional groups (especially carboxylic groups) of AC were proved to be the key factor. AC not only promoted the cracking of PP fragment radicals into light hydrocarbons and the dehydrogenation and aromatization of the resultant light hydrocarbons into aromatic compounds, but also promoted the formation of the intermediate aromatic compounds or polycyclic aromatic hydrocarbons (PAHs) from the reaction of light hydrocarbon products and aromatic compounds. Additionally, AC assisted in situ Ni catalyst (originated from the reduction of Ni 2 O 3 ) catalyzing the dehydrogenation and aromatization of intermediate aromatic compounds or PAHs products to form CNTs. At last, a layer-by-layer assembled mechanism based on benzene rings for the growth of CNTs using PP as carbon source and combined AC/Ni 2 O 3 as catalysts was proposed. This mechanism will help to understand the growth mechanism of CNTs using virgin or waste plastics as carbon sources. More importantly, this approach offers a new potential way for large-scale production of CNTs from waste plastics using cheap AC as a cocatalyst.

HCS (Hollow carbon spheres) covered with metal oxide nanoparticles (SnO 2 and MnO 2 , respectively) were successfully synthesized and investigated regarding their potential as anode materials for lithium-ion batteries. Raman spectroscopy shows a high degree of graphitization for the HCS host structure. The mesoporous nature of the nanocomposites is confirmed by Brunauer–Emmett–Teller analysis. For both metal oxides under study, the metal oxide functionalization of HCS yields a significant increase of electrochemical performance. The charge capacity of HCS/SnO 2 is 370 mA hg −1 after 45 cycles (266 mA hg −1 in HCS/MnO 2 ) which clearly exceeds the value of 188 mA hg −1 in pristine HCS. Remarkably, the data imply excellent long term cycling stability after 100 cycles in both cases. The results hence show that mesoporous HCS/metal oxide nanocomposites enable exploiting the potential of metal oxide anode materials in Lithium-ion batteries by providing a HCS host structure which is both conductive and stable enough to accommodate big volume change effects.

The recycling of waste glass is a major problem for municipalities worldwide. The problem concerns especially colored waste glass which, due to its low recycling rate as result of high level of impurity, has mostly been dumped into landfills. In recent years, a new use was found for it: instead of creating waste, it can be recycled as an additive in building materials. The aim of the study was to evaluate the possibility of manufacturing sustainable and self-cleaning cement mortars with use of commercially available nanomaterials and brown soda-lime waste glass. Mechanical and bactericidal properties of cement mortars containing brown soda-lime waste glass and commercially available nanomaterials (amorphous nanosilica and cement containing nanocrystalline titanium dioxide) were analyzed in terms of waste glass content and the effectiveness of nanomaterials. Quartz sand is replaced with brown waste glass at ratios of 25%, 50%, 75% and 100% by weight. Study has shown that waste glass can act as a successful replacement for sand (up to 100%) to produce cement mortars while nanosilica is incorporated. Additionally, a positive effect of waste glass aggregate for bactericidal properties of cement mortars was observed.

Titania/silica nanomaterials have many possible applications; however, they can be toxic to living organisms, particularly if the material accumulates in niche environments, e.g. areas colonised by actinomycetes. This study therefore investigated the effect of non-activated and UV light-activated titania/silica nanospheres on an environmental Streptomyces strain. The bacteria were incubated with the nanospheres and subsequently cultured on solid medium. The morphology and elemental composition were analysed using optical and electron microscopy (TEM, STEM) and energy-dispersive X-ray spectroscopy (EDX). The appearance of Streptomyces sp. in the experimental and control samples demonstrated that the nanospheres did not have bactericidal properties in the used dose. Furthermore, the observed strain not only survived in the presence of the nanomaterial but also appeared to play a role in its dissolution with an accumulation of the titanium in the intracellular globules of polyphosphate (volutin). Additionally, it was discovered that the UV light-activated titanium dioxide altered the ability of the bacteria to secrete humic acid. The reported phenomenon might be made possible through an accumulation of titanium in the volutin compounds. These findings suggest that streptomycetes could be employed to participate in the dissolution of nanomaterials which enter the natural environment.

In the last decade, nanotechnology has been gathering a spectacular amount of attention in the field of building materials. The incorporation of nanosized particles in a small amount to the building materials can influence their properties significantly. And it can contribute to the creation of novel and sustainable structures. In this work, the effect of nano-Fe3O4 as an admixture (from 1 to 5 wt.% in mass of the cement) on the mechanical and microstructural properties of cementitious composites has been characterised. The study showed that Fe3O4 nanoparticles acted as a filler which improved the microstructure of a cementitious composite and reduced its total porosity, thus increasing the density of the composite. The presence of nanomagnetite did not affect the main hydration products and the rate of cement hydration. In addition, the samples containing nanomagnetite exhibited compressive strength improvement (up to 20 %). The study showed that 3 wt.% of nano-Fe3O4 in the cementitious composite was the optimal amount to improve both its mechanical and microstructural properties.

We present the new promising nanostructure- sandwich-like mesoporous silica nanoflakes synthesized on graphene oxide sheets core. In the first step biocompatibility of the nanoflakes with PEG and without functionalization in human fibroblast, melanoma and breast cancer cells was assessed. In order to define the cellular uptake in vitro and biodistribution in vivo the nanostructures were labelled with fluorescent dye. In the next step, the silica nanostructures were filled by the anticancer drug- methotrexate (MTX) and cytotoxicity of the complex in reference to MTX was evaluated. The WST-1 assay shows mild, but concentration dependent, cytotoxicity of the nanoflakes, most significant for the non-functionalized structures. PEG-modified silica nanoflakes didn't produce a disruption of cell membranes and lactate dehydrogenase (LDH) release. Cell imaging revealed efficient internalization of the silica nanoflakes in cells. Ex vivo organ imaging showed high accumulation of the nanostructures in lungs, bladder and gall bladder, whereas confocal imaging revealed wide nanoflake distribution in all tested tissues, especially at 1h and 4h post intravenous injection. Cytotoxicity of the nanoflake-MTX complex in reference to MTX showed similar cytotoxic potential against cancer cells. These findings may provide useful information for designing drug delivery systems, which may improve anticancer efficacy and decrease side effects.

In the paper the results of research on electronic measurement and control systems designed for a multifunctional graphene-based biosensor are presented. Design of different types of biosensing electrodes based on graphene technology is discussed. Development of electronic circuits for read-out of the biosensor signals based on two microcontroller platforms (ATXmega128A1U and STM32F407) is described, including hardware and software design solutions. Comparison of measurement results using both prototype systems in electrochemical biosensing techniques (EIS - Electrochemical Impedance Spectroscopy) is also presented.

In the paper the results of research on accuracy analysis of measurements in electrochemical biosensing are presented. The scope of performed tests includes EIS (Electrochemical Impedance Spectroscopy) and chronoamperometry, widely used for determination of glucose concentration. Measurement results obtained with two microcontroller systems, designed within a research project, and one reference platform (Autolab system, Metrohm, Netherlands) are compared and discussed. As a result, optimal design solutions may be chosen for microcontroller-based biomeasurement system. In glucosensing, promising results were obtained with the EIS technique in experiments performed using the Autolab system.

Magnetic multi-walled carbon nanotubes-Fe3C nanocomposite (MMWCNTs-ICN) was synthesized by chemical vapor deposition (CVD) process and was used as an adsorbent for the removal of anionic dye Direct Red 23 (DR23) from aqueous solution. The effects of various parameters such as initial DR23 concentration (9–54 mg L−1), pH solution (3.7–11.1) and temperature (20–60 °C) were investigated. The adsorbent was characterized with using several methods such as XRD, HRTEM, EDX, FTIR, BET and particle size distribution by laser diffraction. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Freundlich model. Kinetic adsorption data were analysed using the Lagergren pseudo-first-order kinetic model, the pseudo-second-order model and the intraparticle diffusion model. The regression results showed that the adsorption kinetics was more accurately represented by pseudo-second-order model. Thermodynamics parameters, ΔG°, ΔH° and ΔS°, were calculated. All ΔG° values were negative. The values of enthalpy (ΔH°) and entropy (ΔS°) were 12.6 kJ mol−1 and 61.7 J mol−1 K−1, respectively, indicating that adsorption of DR23 onto MMWCNTs-ICN was spontaneous and endothermic in nature.

A novel way for the synthesis of core/shell structures composed of tin oxide nanoparticles confined in mesoporous hollow carbon spheres (SnO 2 @MHCS) is newly reported. The materials which have a uniform size distribution, good structural stability and large surface area show superior cycling performance and are suitable for high-power anodes. Core/shell structured SnO 2 @MHCS takes advantage of the virtues of SnO 2 and porous carbon in lithium-ion battery. This structure provides a rapid lithium transport pathway and boasts a highly reversible capacity. When the SnO 2 /C ratio is 78.6/21.4 (w/w), the surface area of SnO 2 @MHCS is 183 m 2 g −1 and specific capacity value is 450 mAh g −1 at 1/5 C after 50 cycles. The SnO 2 @MHCS materials have large potential in next-generation lithium-ion batteries.

Lithium tantalate (LiTaO{sub 3}) was successfully synthesized thorough an impregnation method of tantalum pentaoxide in the aqueous solution of lithium hydroxide. Next, the sample was divided into eight batches and calcinated in a temperature range of 450-800 Degree-Sign C. The materials produced were then characterized by X-ray diffraction, Raman spectroscopy, Diffuse Reflectance (DR) UV-vis spectroscopy, BET analysis, and high resolution transmission electron microscopy. Moreover, the samples were tested as photocatalysts in a reaction of hydrogen generation. Interestingly, it was found that the sample calcinated at 550 Degree-Sign C exhibits the highest photocatalytic activity. This sample is composed of 85% of LiTaO{sub 3} and 15% of Ta{sub 2}O{sub 5}. - Highlights: Black-Right-Pointing-Pointer LiTaO{sub 3} was synthesized thorough an impregnation of Ta{sub 2}O{sub 5} and LiOH and calcination at the temperature range of 450-800 Degree-Sign C. Black-Right-Pointing-Pointer Each calcinated sample was tested as photocatalyst in the reaction of hydrogen generation. Black-Right-Pointing-Pointer It was found that the key parameter determining their activity is the sample composition. Black-Right-Pointing-Pointer The sample exhibiting the highest activity is composed of LiTaO{sub 3} (85.1%) and unreacted Ta{sub 2}O{sub 5} (14.9%).

In this paper, we present a study on enhanced photocatalytic performance of TiO2 nanospheres deposited on graphene (n-TiO2-G) in a process of coumarin oxidation. The enhancement of the photoactivity has been observed in respect to commercial TiO2 P25. The presented material was prepared in two steps: (i) hydrolysis of titanium (IV) butoxide (TBT) in ethanol solution with simultaneous deposition on graphene oxide (GO) and (ii) calcination of TiO2-GO to form anatase-TiO2 and reduce GO to graphene. The nanomaterial was characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), Fourier-Transformed Infrared spectroscopy and Raman spectroscopy. In the presented photocatalytic process the fluorescence was used to detect •OH formed on a photo-illuminated n-TiO2-G surface using coumarin which readily reacted with •OH to produce highly fluorescent 7-hydroxycoumarin.

Mesoporous hollow carbon spheres have been fabricated from core-shell structured mesoporous silica sphere using chemical vapor deposition (CVD) with ethylene as a carbon feedstock. The hollow carbon spheres have exhibited relatively high graphitization degree along with good mesa-structural order and high specific surface area of 770 m(2)/g. It was also proved that this material is a great candidate as supercapacitors at high current load. (C) 2012 Elsevier B.V. All rights reserved.

The growth of iron filled multiwalled carbon nanotubes (Fe-MWCNT) using chemical vapour deposition (CVD) has been widely studied. Considering the remarkable magnetic and structural properties of Fe-MWCNT, these materials have been applied in numerous areas. In particular their biomedical application has been explored, where Fe-MWCNT can be used in hyperthermia, acting as a local nano-heater at cellular level. Regarding this aim, the reproducible and highly purified ferromagnetically filled samples of carbon nanotubes are still required. There are several parameters during the synthesis process that influence the properties of the nanotubes. The most favourable temperature of the CNT growth is probably one of the most important issues and its optimisation is crucial. In the current study, the Fe-MWCNT were grown at different temperatures ranging from 650 °C to 1050 °C. Additionally, a comparison between two different CVD systems and two carbon sources are also here presented. The Fe-MWCNT were characterised using diverse techniques regarding the evaluation of their morphology, filling ratio, and purity. Observations showed a strong influence of the growth temperature on the morphology and properties of the Fe-MWCNT. The samples characterisation was performed using Raman spectroscopy, thermogravimetric analysis (TGA), X ray diffraction (XRD), and transmission electron microscopy analysis (TEM).

Carbon nanotubes have unique properties, such as thermal and electrical conductance, which could be useful in the fields of aerospace, microelectronics and biotechnology. However, these properties may vary widely depending on the dimensions, uniformity and purity of the nanotube. Nanotube samples typically contain a significant percentage of more allotropes forms of carbon as well as metal particles left over from catalysts used in manufacturing. Purity characterization of double-walled carbon nanotubes (DWCNTs) is an increasingly popular topic in the field of carbon nanotechnology. In this study, DWCNTs were synthesized in a catalytic reaction, using Fe:MgO as catalyst and methane or methane/ethanol as carbon feedstock for chemical vapor deposition (CVD). The addition of ethanol as carbon feedstock allowed to investigate the influence of oxygen on the sample quality. The purification of the as-produced material from the metallic particles and the catalyst support was performed by sonication in an acid solution. The influence of the duration of the acid treatment using ultrasound on the sample purity was investigated, and the optimal value of this parameter was found. Transmission electron microscopy (TEM) images confirmed the removal of impurities and served to elucidate the morphology of the samples. The purity of carbon nanotubes was analyzed using thermal gravimetric analysis (TGA). The Raman spectra of the samples, as a measure of the concentration of defects, were also reported.