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Optical and thermal effects in asymmetric supercapacitors, whose active-carbon (AC) electrodes were embedded with nano-Si (n-Si) quantum dots (QD), are reported. We describe two structures: (1) p-n-like, obtained by using a polyethylimine (PEI) binder for the “n” electrode and a polyvinylpyrrolidone (PVP) binder for the “p” electrode; (2) a single component binder—poly(methyl methacrylate) (PMMA). In general, AC appears black to the naked eye and one may assume that it indiscriminately absorbs all light spectra. However, on top of a flat lossy spectrum, AC (from two manufacturers) exhibited two distinct absorption bands: one in the blue (~400 nm) and the other one in the near IR (~840 nm). The n-Si material accentuated the absorption in the blue and bleached the IR absorption. Both bands contributed to capacitance increase: (a) when using aqueous solution and a PMMA binder, the optical-related increased capacitance was 20% for low n-Si concentration and more than 100% for a high-concentration dose; (b) when using ion liquid (IL) electrolyte, the large, thermal capacitance increase (of ca. 40%) was comparable to the optical effect (of ca. 42%) and hence was assigned as an optically induced thermal effect. The experimental data point to an optically induced capacitance increase even in the absence of the n-Si dots. Overall, the experimental data suggest intriguing possibilities for optically controlled supercapacitors. Full article

In an attempt to push the boundary of miniaturization, there has been a rising interest in two-dimensional (2D) semiconductors with superior electronic, mechanical, and thermal properties as alternatives for silicon-based devices. Due to their fascinating properties resulting from lowering dimensionality, hexagonal boron nitride (h-BN) and graphene are considered promising candidates to be used in the next generation of high-performance devices. However, neither h-BN nor graphene is a semiconductor due to a zero bandgap in the one case and a too large bandgap in the other case. Here, we demonstrate from first-principles calculations that a hybrid 2D material formed by cross-linking alternating chains of carbon and boron nitride (HCBN) shows promising characteristics combining the thermal merits of graphene and h-BN while possessing the electronic structure characteristic of a semiconductor. Our calculations demonstrate that the thermal properties of HCBN are comparable to those of h-BN and graphene (parent systems). HCBN is dynamically stable and has a bandgap of 2.43 eV. At low temperatures, it exhibits smaller thermal contraction than the parent systems. However, beyond room temperature, in contrast to the parent systems, it has a positive but finitely small linear-thermal expansion coefficient. The calculated isothermal bulk modulus indicates that at high temperatures, HCBN is less compressible, whereas at low temperatures it is more compressible relative to the parent systems. The results of our study are important for the rational design of a 2D semiconductor with good thermal properties. Full article

Glioblastoma multiforme (GBM) is the most aggressive brain cancer. We previously demonstrated the effect of biocompatible surface functionalized graphene quantum dots (GQDs) on GBM cells as chemotherapy enhancers in combination with the antitumor drug doxorubicin (Dox). However, traditional two-dimensional cultures could not represent a reliable model of tumor behavior. In this work, we investigated the effect of carboxylated (COOH-GQDs), aminated (NH₂-GQDs) and unfunctionalized GQDs on a three-dimensional model of neurospheres. Neurospheres are clusters of GBM cells, which formation is driven by the presence of a stem subpopulation involved in cancer malignancy. Tumor recurrence after surgical resection, chemotherapy and radiotherapy indeed depends on the presence of cancer cells with stem properties. We measured a significant reduction in number and size of neurospheres after two weeks of monitoring in the presence of COOH-GQDs and GQDs. Previous works pointed out how variations of membrane fluidity could affect membrane stability and cell-to-cell interactions, thus influencing cell clustering. Therefore, we measured changes in membrane fluidity after administration of GQDs. We found that COOH-GQDs and GQDs significantly increased membrane fluidity with respect to the treatment with NH₂-GQDs or compared to untreated cells. Shifts in the phase of phospholipid bilayer were in accordance with the negative surface net charge of GQDs. We depicted a strong correlation between negatively charged GQDs-induced increase in membrane fluidity and the downregulation of neurospheres formation. Our results indicate that COOH-GQDs and GQDs significantly modulate tumor malignancy by increasing fluidity of cell membrane, with a consequent inhibition of cell-to-cell interaction. Full article

Different carbon nanostructures have been explored as functional materials for the development of effective nanomaterials in cancer treatment applications. This review mainly aims to discuss the features, either strength or weakness, of carbon nanohorn (CNH), carbon conical horn-shaped nanostructures of sp2 carbon atoms. The interest for these materials arises from their ability to couple the clinically relevant properties of carbon nanomaterials as drug carriers with the negligible toxicity described in vivo. Here, we offer a comprehensive overview of the recent advances in the use of CNH in cancer treatments, underlining the benefits of each functionalization route and approach, as well as the biological performances of either loaded and unloaded materials, while discussing the importance of delivery devices. Full article

Carbon dots (CDs) are highly-emissive nanoparticles obtained through fast and cheap syntheses. The understanding of CDs’ luminescence, however, is still far from being comprehensive. The intense photoluminescence can have different origins: molecular mechanisms, oxidation of polyaromatic graphene-like layers, and core-shell interactions of carbonaceous nanoparticles. The citric acid (CA) is one of the most common precursors for CD preparation because of its high biocompatibility, and this review is mainly focused on CA-based CDs. The different parameters that control the synthesis, such as the temperature, the reaction time, and the choice of solvents, were critically described. Particular attention was devoted to the CDs’ optical properties, such as tunable emission and quantum yields, in light of functional applications. The survey of the literature allowed correlating the preparation methods with the structures and the properties of CA-based CDs. Some basic rules to fabricate highly luminescent nanoparticles were selected by the metanalysis of the current literature in the field. In some cases, these findings can be generalized to other types of CDs prepared via liquid phase. Full article

Molybdenum-doped diamond-like carbon (Mo-DLC) coatings have been deposited on titanium β-21S alloy (Ti–15Mo–3Nb–3Al–0.2Si) using plasma-enhanced chemical vapor deposition (PECVD) equipped with pulsed-DC magnetron sputtering. Mo contents in the deposited coatings have been controlled with an applied sputtering pulse duty cycle. Chemical composition, structure, morphology, and topography have been studied using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM), respectively. XRD pattern of the coating with highest Mo content shows the presence of carbide phase. Smooth features with low roughness values are observed in low Mo content coating, whereas high Mo content coating shows granular characteristics with a high roughness value. Raman spectra reveal the increased graphitic content for the highest metal concentration in the coatings, wherein the nanohardness is also determined to be highest, at about ~18–19 GPa. Furthermore, the ball-on-disk tribometry test on Mo-DLC coating with highest nanohardness shows a low coefficient of friction (COF) of 0.2 with low wear loss compared to that of the substrate (0.62). Full article

Carbonaceous nanomaterials have become important materials with widespread applications in battery systems and supercapacitors. The application of these materials requires precise knowledge of their nanostructure. In particular, the porosity of the materials together with the shape of the pores and the total internal surface must be known accurately. Small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) present the methods of choice for this purpose. Here we review our recent investigations using SAXS and SANS. We first describe the theoretical basis of the analysis of carbonaceous material by small-angle scattering. The evaluation of the small-angle data relies on the powerful concept of the chord length distribution (CLD) which we explain in detail. As an example of such an evaluation, we use recent analysis by SAXS of carbide-derived carbons. Moreover, we present our SAXS analysis on commercially produced activated carbons (ACN, RP-20) and provide a comparison with small-angle neutron scattering data. This comparison demonstrates the wealth of additional information that would not be obtained by the application of either method alone. SANS allows us to change the contrast, and we summarize the main results using different contrast matching agents. The pores of the carbon nanomaterials can be filled gradually by deuterated p-xylene, which leads to a precise analysis of the pore size distribution. The X-ray scattering length density of carbon can be matched by the scattering length density of sulfur, which allows us to see the gradual filling of the nanopores by sulfur in a melt-impregnation procedure. This process is important for the application of carbonaceous materials as cathodes in lithium/sulfur batteries. All studies summarized in this review underscore the great power and precision with which carbon nanomaterials can be analyzed by SAXS and SANS. Full article

Presently, the negative electrodes of lithium-ion batteries (LIBs) are constituted by carbon-based materials, which exhibit a limited specific capacity 372 mAh g⁻¹ associated with the cycle in the composition between C and LiC₆. Therefore, many efforts are currently made towards the technological development of nanostructured graphene materials because of their extraordinary mechanical, electrical, and electrochemical properties. Recent progress on advanced hybrids based on graphene oxide (GO) and reduced graphene oxide (rGO) has demonstrated the synergistic effects between graphene and an electroactive material (silicon, germanium, metal oxides (MO_x)) as electrode for electrochemical devices. In this review, attention is focused on advanced materials based on GO and rGO and their composites used as anode materials for lithium-ion batteries. Full article

Indium tin oxide (ITO)-free optoelectronic devices have been discussed for a number of years in the light of a possible indium shortage as demand rises. In particular, this is due to the largely increased number of flat panel displays and especially liquid crystal displays (LCDs) being produced for home entertainment TV and mobile technologies. While a shortage of primary indium seems far on the horizon, nevertheless, recycling has become an important issue, as has the development of ITO-free electrode materials, especially for flexible liquid crystal devices. The main contenders for new electrode technologies are discussed with an emphasis placed on carbon-based materials for LCDs, including composite approaches. At present, these already fulfil the technical specifications demanded from ITO with respect to transmittance and sheet resistance, albeit not in relation to cost and large-scale production. Advantages and disadvantages of ITO-free technologies are discussed, with application examples given. An outlook into the future suggests no immediate transition to carbon-based electrodes in the area of LCDs, while this may change in the future once flexible displays and environmentally friendly smart window solutions or energy harvesting building coverings become available. Full article

The present work aimed to characterize the free vibrations’ behaviour of nanocomposite plates obtained by incorporating graded distributions of carbon nanotubes (CNTs) in a polymeric matrix, considering the carbon nanotubes’ agglomeration effect. This effect is known to degrade material properties, therefore being important to predict the consequences it may bring to structures’ mechanical performance. To this purpose, the elastic properties’ estimation is performed according to the two-parameter agglomeration model based on the Eshelby–Mori–Tanaka approach for randomly dispersed nano-inclusions. This approach is implemented in association with the finite element method to determine the natural frequencies and corresponding mode shapes. Three main agglomeration cases were considered, namely, agglomeration absence, complete agglomeration, and partial agglomeration. The results show that the agglomeration effect has a negative impact on the natural frequencies of the plates, regardless the CNTs’ distribution considered. For the corresponding vibrations’ mode shapes, the agglomeration effect was shown in most cases not to have a significant impact, except for two of the cases studied: for a square plate and a rectangular plate with symmetrical and unsymmetrical CNTs’ distribution, respectively. Globally, the results confirm that not accounting for the nanotubes’ agglomeration effect may lead to less accurate elastic properties and less structures’ performance predictions. Full article

The catalytic removal of nitrate (NO₃⁻) in water using hydrogen as a reducing agent was studied using palladium-copper bimetallic catalysts in different supports. Commercial carbon nanotubes (CNTs), used as received and with different mechanical (CNT (BM 2h)) and chemical modifications (CNT (BM 4h)-N), titanium dioxide (TiO₂) and composite materials (TiO₂-CNT) were considered as main supports for the metallic phase. Different metal loadings were studied to synthesize an optimized catalyst with high NO₃⁻ conversion rate and considerable selectivity for N₂ formation. Among all the studied support materials, the milled carbon nanotubes (sample CNT (BM 2h) was the support that showed the most promising results using 1%Pd-1%Cu as metallic phases. The most active catalysts were 2.5%Pd-2.5%Cu and 5%Pd-2.5%Cu supported on CNT (BM 2h), achieving total conversion after a 120 min reaction with N₂ selectivity values of 62% and 60%, respectively. Reutilization experiments allowed us to conclude that these catalysts were stable during several reactions, in terms of NO₃⁻ conversion rate. However, the consecutive reuse of the catalyst leads to major changes concerning NH₄⁺ selectivity values. Full article

Escherichia coli bacteria were grown inside the channels of cordierite monoliths previously coated with a very good adhered carbon layer. These monolithic structures were tested at room temperature for the nitrate elimination of water solutions working as a batch monolithic bioreactor and showed very good results, as 100% of the nitrates and nitrites were completely removed in the used experimental conditions. Different rate flows of bacteria growth and nitrate elimination were studied, showing that the higher the flow velocity, the faster the nitrate elimination. Finally, the reproducibility tests confirmed the good performance of the proposed bioreactor. Full article

Impurities in carbon dioxide can affect several aspects of the carbon capture and storage process, including storage capacity, rock erosion, accuracy of flow meters, and toxicity of potential leaks. There is an industry need for guidance on performing purity analysis before carbon dioxide is transported and stored. This paper reviews selected reports that specifically provide threshold amount fraction limits for impurities in carbon dioxide for the purpose of transport and storage, with rationales for these limits. A carbon dioxide purity specification is provided (including threshold amount fractions of impurities) on the basis of the findings, as well as recommendations on further work required to develop a suitable gas metrology infrastructure to support these measurements including primary reference materials, sampling methods, and instruments for performing purity analysis. These recommendations provide important guidance to operators and gas analysis laboratories for performing quality assurance. Full article

In this research, a boron-doped diamond (BDD) electrode has been explored to detect the chloroquine drug. The electrochemical performance of BDD electrode towards the irreversible anodic response of chloroquine was investigated by subjecting this electrode to the cathodic (−0.5 A cm⁻² by 180 s, generating a predominantly hydrogen-terminated surface) and anodic (+0.5 A cm⁻² by 30 s, oxygen-terminated surface) pretreatments. The cathodically pretreated BDD electrode ensured a better-defined anodic peak and higher current intensity. Thus, by applying the cathodically pretreated BDD electrode and square-wave voltammetry (SWV), the analytical curve was linear from 0.01 to 0.25 µmol L⁻¹ (correlation coefficient of 0.994), with sensitivity and limit of detection of 12.2 µA L µmol⁻¹ and 2.0 nmol⁻¹, respectively. This nanomolar limit of detection is the lowest recorded so far with modified and unmodified electrodes. Full article

The efficient removal of pollutants from different environments has been one of the great challenges for scientists in recent years. However, the understanding of the mechanisms underlying this phenomenon is still the subject of passionate debates, mainly due to the lack of experimental tools capable of detecting events at the atomic scale. Herein, a comparative theoretical study was carried out to capture the adsorption of H₂S on metal oxide surfaces such as zinc oxide (ZnO) and beryllium oxide (BeO), as well as graphene and Ni-decorated graphene. A simulation based on density-functional theory (DFT) was carried out by adopting General Gradient Approximation (GGA) under the Perdew–Burke–Ernzerhof (PBE) function. The calculations quantified H₂S adsorption on the considered metal oxide sheets as well as on the non-decorated graphene having a physical nature. In contrast, H₂S adsorbed on Ni-decorated graphene sheet gave an adsorption energy of −1.64 eV due to the interaction of S and Ni atoms through the formation of a covalent bond, proof of chemisorption. It seems that the graphene sheet decorated with Ni atoms is a more suitable adsorbent for H₂S molecules than BeO, ZnO, or non-decorated graphene, providing a theoretical basis for future studies. Full article

Hierarchically porous activated carbon materials from agro-waste, Jackfruit seeds are prepared by a chemical activation method involving the treatment with zinc chloride (ZnCl₂) at different temperatures (600–1000 °C). The electrochemical supercapacitance performances of the prepared materials were studied in an aqueous electrolyte (1 M sulfuric acid, H₂SO₄) in a three-electrode system. Jackfruit seed carbons display nanoporous structures consisting of both micro- and mesopore architectures and they are amorphous in nature and also contain oxygenated surface functional groups, as confirmed by powder X-ray diffraction (pXRD), Raman scattering, and Fourier-transformed infrared (FTIR) spectroscopy, respectively. The surface areas and pore volumes were found to be 1216.0 to 1340.4 m²·g⁻¹ and 0.804 to 1.144 cm³·g⁻¹, respectively, demonstrating the better surface textural properties compared to the commercial activated carbons. Due to the high surface area, large pore volume, and well developed hierarchical micro- and mesoporosity, the optimal sample achieved a high specific capacitance of 292.2 F·g⁻¹ at 5 mV·s⁻¹ and 261.3 F·g⁻¹ at 1 A·g⁻¹ followed by outstanding high rate capability. The electrode sustained 71.6% capacity retention at a high current density of 20 A·g⁻¹. Furthermore, the electrode displayed exceptional cycling stability with small capacitance loss (0.6%) even after 10,000 charging–discharging cycles, suggesting that Jackfruit seed would have potential in low-cost and scalable production of nanoporous carbon materials for supercapacitors applications. Full article

A wideband non-resonant absorber is proposed, and its radar cross section (RCS) reduction is investigated. A discussion on the functional materials available is followed by the design of an absorber on a Plexiglas substrate with polyaniline-graphene nanocomposite as layered square inclusions with thicknesses and conductivities scaled to golden ratio. The measured dielectric properties of polyaniline-graphene nanocomposites are used in the fullwave simulation. The design parameters have been identified and optimized using CST Microwave Studio. As designed structure is fabricated and the reflection is measured. The objective of the work is to demonstrate the use of non-metallic conducting polymer composites devoid of metals for radar absorbing material (RAM) structural designs. The structure is an all-polymer and electrically thin design with a potential to be 3D printed to suit the target object. Full article

This paper reviews the ways in which C₆₀ and other fullerene molecules can be incorporated into polymeric structures. Firstly, polymers in which the fullerenes are incorporated into the structure by covalent or noncovalent bonding are discussed. These include “pearl necklace” structures, “charm bracelet” structures, organometallic polymers, crosslinked polymers, end-capped polymers, star-shaped polymers and supramolecular polymers. Secondly, all-carbon polymers, which are produced by fusing fullerenes together, are covered. The synthesis and properties of each class of fullerene polymer are outlined and the prospects for commercial applications considered. Full article