In the past, sodium alanate, NaAlH4, has been widely investigated for its capability to store hydrogen, and its potential for improving storage properties through nanoconfinement in carbon scaffolds ...has been extensively studied. NaAlH4 has recently been considered for Li-ion storage as a conversion-type anode in Li-ion batteries. Here, NaAlH4 nanoconfined in carbon scaffolds as an anode material for Li-ion batteries is reported for the first time. Nanoconfined NaAlH4 was prepared by melt infiltration into mesoporous carbon scaffolds. In the first cycle, the electrochemical reversibility of nanoconfined NaAlH4 was improved from around 30 to 70% compared to that of nonconfined NaAlH4. Cyclic voltammetry revealed that nanoconfinement alters the conversion pathway, and operando powder X-ray diffraction showed that the conversion from NaAlH4 into Na3AlH6 is favored over the formation of LiNa2AlH6. The electrochemical reactivity of the carbon scaffolds has also been investigated to study their contribution to the overall capacity of the electrodes.
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•Polyaniline-derived activated carbon was studied for H2 storage and supercapacitors.•A known commercial activated carbon with larger pore sizes was used as a reference.•Strong ...interaction with H2 and reversible H2 uptake of ~5.5 wt% at 77 K and ~60 bar.•Excellent electrochemical energy storage behavior using an aqueous CsCl electrolyte.•Smaller pore sizes are responsible for the enhanced performance in both applications.
The development and in-depth characterization of multifunctional materials with versatile use in energy and environmental applications has been a topic of on-going investigations. In this work, a nanoporous polymer-/polyaniline-derived activated carbon (PDAC), with large surface area (~2200 m2/g) and large pore volume (~1 cm3/g), was thoroughly studied towards its applicability for H2 storage and supercapacitor energy storage. The PDAC demonstrated a superior H2 adsorption performance under cryogenic conditions, reaching a high and fully reversible excess gravimetric H2 uptake of ~5.5 wt% at 77 K and ~60 bar, along with a ~8.3 kJ/mol heat of adsorption at zero coverage. Furthermore, thin PDAC electrodes with an aqueous CsCl electrolyte were combined in a supercapacitor cell that exhibited a gravimetric capacitance of ~130 F/g for a 0.5 mV/s scanning rate along with a 99% coulombic efficiency and a 100% capacitance retention after 2500 charge/discharge cycles. The PDAC material showed substantially improved H2 and electrochemical energy storage performance compared to a well-established commercial activated carbon, which is attributed to the overall smaller pore sizes of the PDAC structure.
In this work, the effect of two different types of bioactive coatings on the properties of 3D printed poly(lactic acid)/montmorillonite (PLA/MMT) nanocomposite scaffolds was examined. To improve ...their suitability for bone tissue engineering applications, the PLA nanocomposite scaffolds were coated with (i) ordered mesoporous Strontium bioglass (SrBG) and (ii) SrBG and nanohydroxyapatite (nHA) using a simple dip coating procedure. The effect of the coatings on the morphology, chemical structure, wettability and nanomechanical properties of the scaffolds was examined. The hydrophilicity of PLA nanocomposite scaffolds increased after the SrBG coating and increased even more with the SrBG/nHA coating. Moreover, in the case of PLA/MMT/SrBG/nHA 3D printed scaffolds, the elastic modulus increased by ~ 80% and the hardness increased from 156.9 ± 6.4 to 293.6 ± 11.3 MPa in comparison with PLA. Finally, the in vitro biocompatibility and osteogenic potential were evaluated using bone marrow-derived stem cells. The coating process was found to be a fast, economical and effective way to improve the biomineralization and promote the differentiation of the stem cells toward osteoblasts, in comparison with the neat PLA and the PLA/MMT nanocomposite scaffold.
In this work, the effect of two different types of bioactive coatings on the properties of 3D printed poly(lactic acid)/montmorillonite (PLA/MMT) nanocomposite scaffolds was examined. To improve ...their suitability for bone tissue engineering applications, the PLA nanocomposite scaffolds were coated with (i) ordered mesoporous Strontium bioglass (SrBG) and (ii) SrBG and nanohydroxyapatite (nHA) using a simple dip coating procedure. The effect of the coatings on the morphology, chemical structure, wettability and nanomechanical properties of the scaffolds was examined. The hydrophilicity of PLA nanocomposite scaffolds increased after the SrBG coating and increased even more with the SrBG/nHA coating. Moreover, in the case of PLA/MMT/SrBG/nHA 3D printed scaffolds, the elastic modulus increased by ~ 80% and the hardness increased from 156.9 ± 6.4 to 293.6 ± 11.3 MPa in comparison with PLA. Finally, the in vitro biocompatibility and osteogenic potential were evaluated using bone marrow-derived stem cells. The coating process was found to be a fast, economical and effective way to improve the biomineralization and promote the differentiation of the stem cells toward osteoblasts, in comparison with the neat PLA and the PLA/MMT nanocomposite scaffold.
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Metal-carbon composites have shown considerable hydrogen storage potential at room temperature. In the present work the behaviour of two different Pd amalgam doped carbon substrates, namely a ...carbogenic foam and a mildly oxidised ordered mesoporous carbon, are compared on the basis of their hydrogen sorption properties at 77 and 298 K and low pressures, aiming to investigate the effect of surface on the storage capacity. In both cases, the introduction of alloy nanoparticles leads to an improvement of the hydrogen uptake with respect to pure carbons. This effect is significant for the carbogenic foam however small for the ordered carbon.
The critical effect of confinement on the interaction of hydrogen isotopes (H2 and D2) with carbon surfaces was investigated through a combined low temperature adsorption/thermal desorption ...spectroscopy (TDS) study on three carbon molecular sieves (CMS) possessing nanopores with nominal sizes between 0.3 and 0.5nm. The porous structure and the sorption properties of all three adsorbents were characterized by N2 (77K) and CO2 (273K), as well as H2 and D2 (77K) low pressure (up to 1bar) adsorption measurements. The interaction of the carbons with hydrogen, deuterium, and an isotopic H2/D2 gas mixture was further studied by means of TDS measurements, extended to temperatures down to 20K. The differences in the H2/D2 adsorption/desorption profiles of the three CMS samples are correlated with the respective micropore size distributions. The presence of very narrow micropores, with size close to the kinetic diameter of the hydrogen molecule, resulted in enhanced hydrogen (both for H2 and D2) interactions, giving rise to a TDS maximum centered on 122K, the highest desorption temperature ever measured for the desorption of physisorbed hydrogen. Furthermore, the quantum effects on hydrogen/deuterium adsorption on CMS adsorbents have been addressed for the first time using the TDS technique.
In this work, two types of mesoporous carbon particles with different morphology, size, and pore structure have been functionalized with a self-immolative polymer sensitive to changes in pH and ...tested as drug nanocarriers. It is shown that their textural properties allow significantly higher loading capacity compared to typical mesoporous silica nanoparticles. In vial release experiments of a model Ru dye at pH 7.4 and 5 confirm the pH-responsiveness of the hybrid systems, showing that only small amounts of the cargo are released at physiological pH, whereas at slightly acidic pH (e.g., that of lysosomes), self-immolation takes place and a significant amount of the cargo is released. Cytotoxicity studies using human osteosarcoma cells show that the hybrid nanocarriers are not cytotoxic by themselves but induce significant cell growth inhibition when loaded with a chemotherapeutic drug such as doxorubicin. In preparation of an in vivo application, in vial responsiveness of the hybrid system to short-term pH-triggering is confirmed. The consecutive in vivo study shows no substantial cargo release over a period of 96 h under physiological pH conditions. Short-term exposure to acidic pH releases an experimental fluorescent cargo during and continuously after the triggering period over 72 h.
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