Regulation pore size distribution for facilitating malachite green removal on carbon foam.

Malachite green (MG) is widely used as a textile dye and an aquacultural biocide, and become a serious pollution of drink water, but effectually isolating and removing it from wastewater are still a challenge. Here we report a new strategy to prepare a carbon foam with tunable pore size distribution by a one-pot lava foam process. We find that uniform micropore size is beneficial to the formation of C-OH coordination on the pore surface, increasing MG adsorption rates via H+ ionization. As a result, carbon foam with uniform pore size distribution demonstrates an optimum MG removal efficiency of 1812 mg g-1 and a higher partition coefficient of 3.02 mg g-1 µM-1, which is twice that of carbon foams with irregular pore size distribution. The adsorption of MG onto these adsorbents was found to be an endothermic monolayer chemical adsorption process, and the Gibbs free energy of adsorption process was decreased obviously by regulating micropore size distribution. The experiment results are in good agreement with pseudo-second-order kinetic and Langmuir isotherm models. Revealed the pore size distribution was the critical factor of MG removal by carbon foam. It should be and inspiration for the design and development of highly efficiency adsorbents for dyes removal.

Microscopic origin of graphene nanosheets derived from coal-tar pitch by treating Al4C3 as the intermediate.

The development of environmentally friendly, simple process and low cost synthesis methods for preparing graphene nanosheets (GNs) has attracted global interest. In this work, a simple and efficient method to synthesize GNs deriving from coal-tar pitch has been proposed from both experimental and theoretical point of views. The XRD, TEM and Raman results demonstrate that precursor Al4C3 could provide a growth environment for the final product of GNs. Innovatively, we have unraveled the microscopic origin for the decomposition of Al4C3 based on density functional theory calculations. It is highlighted that the surface energies and the analysis of elastic constants indicate the fact that the chemical etching process in Al4C3 can happen, which is similar to the exfoliation of well-known transition metal carbides MXenes. Furthermore, different bond breaking mechanisms have been found in Al4C3 at applied tensile and shear strains from the electron localization functions and stress-strain results. Our study not only offers an efficient method to synthesize GNs, but also to unravel the microscopic mechanism of fabrication by theoretical calculations.

Facile preparation of robust dual MgO-loaded carbon foam as an efficient adsorbent for malachite green removal.

This study developed a facile approach for the fabrication of dual MgO-loaded carbon foam (DMCF) via carbonization of a cured MgO/cyanate ester resin mixture, which underwent self-foaming of the resin followed by the carbothermal reduction of MgO. The features of the prepared DMCF prepared were characterized by FESEM, TEM, XRD, FTIR, XPS and so on, and the effects of adsorption conditions, adsorption isotherms, kinetics, and thermodynamics on malachite green (MG) removal using the DMCF as adsorbents were investigated through batch adsorption experiments. Results demonstrate that the DMCF possesses a unique dual loading of MgO particles which are not only loaded onto its foam walls but also filled within the walls with a graphene-wrapped core-shell structure. The experimental maximum adsorption capacity of MG reaches up to 1874.18 mg/g with a partition coefficient of 10.87 mg/g/µM. The adsorption process can be better described with Langmuir, pseudo-second-order, and intraparticle diffusion models. Moreover, the DMCF exhibits a removal percentage of 84.85% after five reuses, indicating that it is an efficient and promising adsorbent for MG adsorption.

A stiff ZnO/carbon foam composite with second-level macroporous structure filled ZnO particles for heavy metal ions removal.

A stiff zinc oxide/carbon foam (ZnO/CF) composite as a desirable adsorbent for heavy metal ions was innovatively designed and fabricated by loading ZnO particles into a carbon foam with capsule-like second-level macropores. The features of the resulting composite were characterized by FESEM, XRD, BET, FTIR, and XPS. The effects of adsorption parameters on the Pb(II), Cr(III), and Cu(II) ions removal were studied through batch experiments. Results show that the ZnO/CF composite possesses a second-level macroporous structure filled ZnO particles, which has both mesoporous structure and Zn-O-C bond with the strongly synergistic effect. And meanwhile, it has a relatively high compression strength of 2.18 MPa at a density of 0.18 g cm-3. The experimental maximum adsorption capacities for Pb(II), Cr(III), and Cu(II) ions reach 170.85 mg g-1, 168.74 mg g-1, and 104.61 mg g-1 with relatively high partition coefficients of 5.803 mg g-1 µM-1, 1.169 mg g-1 µM-1, and 0.648 mg g-1 µM-1, respectively. The experimental data are in accordance with Langmuir isotherm and pseudo-second-order kinetic model. Moreover, the composite still exhibits a good adsorption performance even after five cycles.

A novel hierarchical stiff carbon foam with graphene-like nanosheet surface as the desired adsorbent for malachite green removal from wastewater.

A novel hierarchical stiff carbon foam (HSCF) was successfully prepared via a carbothermal reduction between the carbon foam with two-level pore structure and the Al2O3 from aluminum sulfate, and used as a bulk adsorbent for removing malachite green (MG) dye. The structures of the HSCF were characterized using SEM, XRD, FTIR, BET, and XPS, and the effects of adsorption condition on the MG removal were studied through batch adsorption experiments. Results show that large-sized and complex-shaped HSCF can be easily fabricated with a high compression strength of 1.58 MPa at a low bulk density (0.10 g cm-3). The HSCF possesses a fluffy graphene-like nanosheet surface with a mesoporous structure and meanwhile exhibits good hydrophilicity loaded with aluminum hydroxide. The experimental maximum adsorption capacity for MG reaches 425.2 mg g-1 with a relatively high partition coefficient of 9.38 mg g-1 µM-1 at the optimal condition. The experimental data are in good agreement with Langmuir isotherm and pseudo-second-order kinetic model, and meanwhile, the adsorption of MG onto the HSCF is a spontaneous and endothermic process. Also, the HSCF still exhibits good adsorption ability and stability after seven regeneration cycles.

Self-assembled poly(N-methylaniline)-lignosulfonate spheres: from silver-ion adsorbent to antimicrobial material.

Self-assembled poly(N-methylaniline)-lignosulfonate (PNMA-LS) composite spheres with reactive silver-ion adsorbability were prepared from N-methylaniline by using lignosulfonate (LS) as a dispersant. The results show that the PNMA-LS composite consisted of spheres with good size distribution and an average diameter of 1.03-1.27 µm, and the spheres were assembled by their final nanofibers with an average diameter of 19-34 nm. The PNMA-LS composite spheres exhibit excellent silver-ion adsorption; the maximum adsorption capacity of silver ions is up to 2.16 g g(-1) at an adsorption temperature of 308 K. TEM and wide-angle X-ray results of the PNMA-LS composite spheres after absorption of silver ions show that silver ions are reduced to silver nanoparticles with a mean diameter of about 11.2 nm through a redox reaction between the PNMA-LS composite and the silver ions. The main adsorption mechanism between the PNMA-LS composite and the silver ions is chelation and redox adsorption. In particular, a ternary PNMA-LS-Ag composite achieved by using the reducing reaction between PNMA-LS composite spheres and silver ions can be used as an antibacterial material with high bactericidal rate of 99.95 and 99.99% for Escherichia coli and Staphylococcus aureus cells, respectively.

Continuous Dual-Scale Interpenetrating Network Carbon Foam-Stearic Acid Composite as a Shape-Stabilized Phase Change Material with a Desirable Synergistic Effect.

For enhancing the heat storage and encapsulation performances of organic phase change materials (PCMs), a carbon foam (CF) with a continuous dual-scale pore structure (DCF) was developed. Employing the as-prepared DCF as a stearic acid (SA) support, a novel shape-stabilized SA-CF composite PCM with a continuous dual-scale interpenetrating network structure was achieved through the impregnation of SA into the DCF. DCF-900, prepared at an activation temperature of 900 °C, possesses a high loading capacity of 89.54 wt % for melted SA without leakage. The resulting SA/DCF-900 composite with a continuous dual-scale interpenetrating network structure exhibits excellent comprehensive performances with a good synergistic effect. The composite presents a thermal conductivity of 1.298 W/m·K and an encouraging compressive strength of 9.03 MPa, which increase by 2.25-fold and 3.56-fold compared with those of DCF-900, respectively. Furthermore, its melting and freezing enthalpies reach 192.8 and 192.7 J/g with a storage efficiency of about 100%, respectively; meanwhile, it displays excellent thermal cycle stability and reversibility after 600 thermal cycles with a high melting/freezing enthalpy retention rate of up to 96%. More importantly, its light-to-thermal conversion efficiency reaches 91.8% under a light intensity of 100 mW/cm2. Consequently, the SA/DCF-900 composite is a promising candidate for high-performance PCMs.

Influence of Al-O and Al-C Clusters on Defects in Graphene Nanosheets Derived from Coal-Tar Pitch via Al4C3 Precursor.

By treating Al4C3 as the precursor and growth environment, graphene nanosheets (GNs) can efficiently be derived from coal-tar pitch, which has the advantages of simple preparation process, high product quality, green environmental protection, low equipment requirements and low preparation cost. However, the defects in the prepared GNs have not been well understood. In order to optimize the preparation process, based on density functional theory calculations, the influence mechanism of Al-O and Al-C clusters on defects in GNs derived from coal-tar pitch via Al4C3 precursor has been systematically investigated. With minute quantities of oxygen-containing defects, Al-O and Al-C clusters have been realized in the prepared GNs from X-ray photoelectron spectroscopy analysis. Therefore, the influences of Al-O and Al-C clusters on graphene with vacancy defects and oxygen-containing defects are systematically explored from theoretical energy, electron localization function and charge transfer analysis. It is noted that the remaining Al-O and Al-C clusters in GNs are inevitably from the thermodynamics point of view. On the other hand, the existence of defects is beneficial for the further adsorption of Al-O and Al-C clusters in GNs.

Exceptional Mechanical Properties and Heat Resistance of Photocurable Bismaleimide Ink for 3D Printing.

Photosensitive resins used in three-dimensional (3D) printing are characterized by high forming precision and fast processing speed; however, they often possess poor mechanical properties and heat resistance. In this study, we report a photocurable bismaleimide ink with excellent comprehensive performance for stereolithography (SLA) 3D printing. First, the main chain of bismaleimide with an amino group (BDM) was synthesized, and then, the glycidyl methacrylate was grafted to the amino group to obtain the bismaleimide oligomer with an unsaturated double bond. The oligomers were combined with reaction diluents and photo-initiators to form photocurable inks that can be used for SLA 3D printing. The viscosity and curing behavior of the inks were studied, and the mechanical properties and heat resistance were tested. The tensile strength of 3D-printed samples based on BDM inks could reach 72.6 MPa (166% of that of commercial inks), glass transition temperature could reach 155 °C (205% of that of commercial inks), and energy storage modulus was 3625 MPa at 35 °C (327% of that of commercial inks). The maximum values of T-5%, T-50%, and Tmax of the 3D samples printed by BDM inks reached 351.5, 449.6, and 451.9 °C, respectively. These photocured BDM inks can be used to produce complex structural components and models with excellent mechanical and thermal properties, such as car parts, building models, and pipes.

The interlayer coupling modulation of a g-C3N4/WTe2 heterostructure for solar cell applications.

Constructing van der Waals (vdW) heterostructures has been proved to be an excellent strategy to design or modulate the physical and chemical properties of 2D materials. Here, we investigated the electronic structures and solar cell performances of the g-C3N4/WTe2 heterostructure via first-principles calculations. It is highlighted that the g-C3N4/WTe2 heterostructure presents a type-II band edge alignment with a band gap of 1.24 eV and a corresponding visible light absorption coefficient of ∼106 cm-1 scale. Interestingly, the band gap of the g-C3N4/WTe2 heterostructure could increase to 1.44 eV by enlarging the vdW gap to harvest more visible light energy. It is worth noting that the decreased band alignment difference resulting from tuning the vdW gap, leads to a promotion of the power conversion efficiency up to 17.68%. This work may provide theoretical insights into g-C3N4/WTe2 heterostructure-based next-generation solar cells, as well as a guide for tuning properties of vdW heterostructures.

Preparation of discrete cage-like oxidized hollow carbon spheres with vertically aligned graphene-like nanosheet surface for high performance Pb2+ absorption.

A novel oxidized hollow carbon sphere (OHCS) as absorbent for the removal of Pb2+ was fabricated from the mixture of coal-tar pitch and aluminum isopropoxide followed by nitric acid oxidation. The as-prepared OHCSs were characterized by FESEM, TEM, BET, TG, FTIR and XPS, and meanwhile the effects of adsorption conditions on the Pb2+ removal were investigated by batch experiments. Results show that the OHCSs prepared possess discrete cage-like structures and well-defined inner/outer surface features, exhibiting vertically aligned graphene-like nanosheets on their surfaces with mesoporous nature and high hydrophobicity. The maximum absorption capacity for Pb2+ of the OHCSs can reach 280.79 mg g-1 at the optimum condition. The adsorption kinetic of Pb2+ onto the OHCSs was found to be well modeled by pseudo-second-order kinetic model, and the experimental equilibrium data were represented well by Langmuir isotherm model. Moreover, the OHCSs still exhibit excellent adsorption ability and stability after recycling 5 times, indicating its excellent reusability performance. Overall, the OHCS is a promising adsorbent for Pb2+ removal.

Preparation and application of porous nitrogen-doped graphene obtained by co-pyrolysis of lignosulfonate and graphene oxide.

Nitrogen-doped graphene with in-plane porous structure was fabricated by simple co-pyrolysis of lignosulfonate and graphene oxide in the presence of urea. Lignosulfonate first performs as a dispersant adsorbed on the surface of graphene oxide to prevent the aggregation of graphene oxide sheets for preparing homogeneous nitrogen-containing precursor, and then acts as a porogen to render graphene sheets with nanopores in the pyrolysis process of the nitrogen-containing precursor. Urea was used as a nitrogen source to incorporate nitrogen atoms into graphene basal plane. The special nanoporous structure combined with nitrogen content of 7.41at.% endows the nitrogen-doped graphene electrode material with super capacitance up to 170Fg(-1), high rate performance, and excellent cycling stability.

Fabrication, characterization and application of nitrogen-containing carbon nanospheres obtained by pyrolysis of lignosulfonate/poly(2-ethylaniline).

Lignosulfonate/poly(2-ethylaniline) (LS-PEA) composite nanospheres were prepared via in situ polymerization of 2-ethylaniline (EA) with lignosulfonate (LS) as a dispersant. LS-PEA nanospheres with an average diameter of 155 nm were obtained at an optimal LS concentration of 20 wt.%. Subsequently, nitrogen-containing carbon nanospheres were fabricated via direct pyrolysis of the LS-PEA composite nanospheres at 600-800 °C. The carbon nanospheres prepared by pyrolysis were used as anodes of lithium-ion batteries. The first charge and discharge capacity of carbon nanospheres prepared at 700 °C at current densities of 60 and 100 mA g(-1) were 980 and 432 mAh g(-1), and 764 and 342 mAh g(-1), respectively. The batteries still owned a high capacity of 353 and 296 mAh g(-1) after 20 cycles. The results indicated that these nitrogen-containing carbon nanospheres could be used as a promising candidate for electrode materials of lithium-ion batteries.

Fabrication of poly(N-ethylaniline)/lignosulfonate composites and their carbon microspheres.

Novel poly(N-ethylaniline)/lignosulfonate (PNA-LS) composites were prepared via an in situ polymerization of N-ethylaniline (NA) with lignosulfonate (LS) as a dispersant. Nitrogen-containing carbon materials were obtained by direct pyrolysis of the PNA-LS composites at the pyrolytic temperatures ranging from 300°C to 1200°C. The as-prepared PNA-LS composites and their carbon materials were investigated by TGA, SEM, TEM, FTIR and UV-vis spectra, XRD and elemental analysis. The results showed that the morphology, structure and properties of the PNA-LS composites were depended on the LS:NA mass ratio. PNA-LS microspheres with an average diameter of 1300 nm could be fabricated when the LS:NA mass ratio was 2.5:97.5, while regular hexagon sheets of PNA-LS composite were obtained with the LS:NA mass ratio above 5:95. Furthermore, nitrogen-containing carbon nanospheres with an average diameter of 820 nm were achieved at the carbonization temperature of 800°C.