Search Results (19)

Carbon nanomaterials that include different forms such as graphene, carbon nanotubes, fullerenes, graphite, nanodiamonds, carbon nanocones, amorphous carbon, as well as porous carbon, are quite distinguished by their unique structural, electrical, and mechanical properties. This plays a major role in making them pivotal in various medical applications. The synthesis methods used for such nanomaterials, including techniques such as chemical vapor deposition (CVD), arc discharge, laser ablation, and plasma-enhanced chemical vapor deposition (PECVD), are able to offer very precise control over material purity, particle size, and scalability, enabling for nanomaterials catered for different specific applications. These materials have been explored in a range of different systems, which include drug-delivery systems, biosensors, tissue engineering, as well as advanced imaging techniques such as MRI and fluorescence imaging. Recent advancements, including green synthesis strategies and novel innovative approaches like ultrasonic cavitation, have improved both the precision as well as the scalability of carbon nanomaterial production. Despite challenges like biocompatibility and environmental concerns, these nanomaterials hold immense promise in revolutionizing personalized medicine, diagnostics, and regenerative therapies. Many of these applications are currently positioned at Technology Readiness Levels (TRLs) 3–4, with some systems advancing toward preclinical validation, highlighting their emerging translational potential in clinical settings. This review is specific in evaluating synthesis techniques of different carbon nanomaterials and establishing their modified properties for use in biomedicine. It focuses on how these techniques establish biocompatibility, scalability, and performance for use in medicines such as drug delivery, imaging, and tissue engineering. The implications of nanostructure behavior in biological environments are further discussed, with emphasis on applications in imaging, drug delivery, and biosensing. Full article

We elaborate a method for determining the 0D–1D nanostructure size by photoluminescence (PL) emission spectrum dependence on the nanostructure dimensions. As observed, the high number of diamond-like carbon nanocones shows a strongly blue-shifted PL spectrum compared to the bulk material, allowing for the calculation of their top dimensions of 2.0 nm. For the second structure model, we used a sharp atomic force microscope (AFM) tip, which showed green emission localized on its top, as determined by confocal microscopy. Using the PL spectrum, the calculation allowed us to determine the tip size of 1.5 nm, which correlated well with the SEM measurements. The time-resolved PL measurements shed light on the recombination process, providing stretched-exponent decay with a τ₀ = 1 ns lifetime, indicating a gradual decrease in exciton lifetime along the height of the cone from the base to the top due to surface and radiative recombination. Therefore, the proposed method provides a simple optical procedure for determining an AFM tip or other nanocone structure sharpness without the need for sample preparation and special expensive equipment. Full article

Freeform carbon fibres were 3D-printed from CH₃OH:H₂O mixtures using hyperbaric-pressure laser chemical vapour deposition (HP-LCVD). The experiment overlapped a region of known diamond growth, with the objective of depositing diamond-like carbon without the use of plasmas or hot filaments. A high-pressure regime was investigated for the first time through the precursor’s critical point. Seventy-two C-fibres were grown from 13 different CH₃OH:H₂O mixtures at total pressures between 7.8 and 180 bar. Maximum steady-state axial growth rates of 14 µm/s were observed. Growth near the critical point was suppressed, ostensibly due to thermal diffusion and selective etching. In addition to nanostructured graphite, various carbon allotropes were synthesised at/within the outer surface of the fibres, including diamond-like carbon, graphite polyhedral crystal, and tubular graphite cones. Several allotropes were oversized compared to structures previously reported. Raman spectral pressure–temperature (P-T) maps and a pictorial P-T phase diagram were compiled over a broad range of process conditions. Trends in the Raman I_D/I_G and I_2D/I_G intensity ratios were observed and regions of optimal growth for specific allotropes were identified. It is intended that this work provide a basis for others in optimising the growth of specific carbon allotropes from methanol using HP-LCVD and similar CVD processes. Full article

In this work, the hydration of calcium aluminate cement (CAC, Al₂O₃ ≥ 70%) paste with nano admixtures (0, 0.05%, 0.1% and 0.2%) of nano-silica (NS) and carbon nano-cones (NC) when W/CAC = 0.35 was investigated. The methods of calorimetry, thermal analysis, X-ray diffraction (XRD), IR spectroscopy, and scanning electron microscopy (SEM) were used. In addition, the physical and mechanical properties of hardened cement pastes were determined after 3 days of hardening. NS was found to shorten the induction period of CAC hydration and accelerate the time of the secondary heat release effect, especially in the specimens with the highest NS content. The incorporation of NC (up to 0.2%) slows down the hydration process. After 3 days of hydration, the formation of hydration products, such as C₂AH₈, CAH₁₀, C₃AH₆ and AH₃ hydrates, was observed in CAC pastes, however, the quantitative compositions were different depending on the kind of nano admixture and its amount. SEM results obtained show differences in the effect of NS and NC on the formation of the structure of cement paste during its hardening. Significant changes in CAC paste microstructure were caused by the addition of NS and NC admixtures. Compressive strength was found to increase with the increase of NS and the optimal NS content was found to be 0.10 wt.%. The modification of the cement paste with an NS admixture results in a higher amount of hydrates, lower total porosity, and a higher amount of the smallest pores in the microstructure of the sample. NS and NC influence the hydration behaviour of CAC in different ways, which causes characteristic changes in the microstructure and properties of hardened samples. Full article

Flexible pressure sensors still face difficulties achieving a constantly adaptable micronanostructure of substrate materials. Interlinked microcone resistive sensors were fabricated by polydimethylsiloxane (PDMS) nanocone array. PDMS nanocone array was achieved by the second transferring tapered polymethyl methacrylate (PMMA) structure. In addition, self-assembly 2D carbon nanotubes (CNTs) networks as a conducting layer were prepared by a low-cost, dependable, and ultrafast Langmuir–Blodgett (LB) process. In addition, the self-assembled two-dimensional carbon nanotubes (CNTs) network as a conductive layer can change the internal resistance due to pressure. The results showed that the interlinked sensor with a nanocone structure can detect the external pressure by the change of resistivity and had a sensitive resistance change in the low pressure (<200 Pa), good stability through 2800 cycles, and a detection limit of 10 kPa. Based on these properties, the electric signals were tested, including swallowing throat, finger bending, finger pressing, and paper folding. The simulation model of the sensors with different structural parameters under external pressure was established. With the advantages of high sensitivity, stability, and wide detection range, this sensor shows great potential for monitoring human motion and can be used in wearable devices. Full article

We use molecular dynamics to compute the free energy of carbon nanoparticles crossing a hydrophobic–hydrophilic interface. The simulations are performed on a biphasic system consisting of immiscible solvents (i.e., cyclohexane and water). We solvate a carbon nanoparticle into the cyclohexane layer and use a pull force to drive the nanoparticle into water, passing over the interface. Next, we accumulate a series of umbrella sampling simulations along the path of the nanoparticle and compute the solvation free energy with respect to the two solvents. We apply the method on three carbon nanoparticles (i.e., a carbon nanocone, a nanotube, and a graphene nanosheet). In addition, we record the water-accessible surface area of the nanoparticles during the umbrella simulations. Although we detect complete wetting of the external surface of the nanoparticles, the internal surface of the nanotube becomes partially wet, whereas that of the nanocone remains dry. This is due to the nanoconfinement of the particular nanoparticles, which shields the hydrophobic interactions encountered inside the pores. We show that cyclohexane molecules remain attached on the concave surface of the nanotube or the nanocone without being disturbed by the water molecules entering the cavity. Full article

The nanocone-shaped carbon nanotubes field-emitter array (NCNA) is a near-ideal field-emitter array that combines the advantages of geometry and material. In contrast to previous methods of field-emitter array, laser ablation is a low-cost and clean method that does not require any photolithography or wet chemistry. However, nanocone shapes are hard to achieve through laser ablation due to the micrometer-scale focusing spot. Here, we develop an ultraviolet (UV) laser beam patterning technique that is capable of reliably realizing NCNA with a cone-tip radius of ≈300 nm, utilizing optimized beam focusing and unique carbon nanotube–light interaction properties. The patterned array provided smaller turn-on fields (reduced from 2.6 to 1.6 V/μm) in emitters and supported a higher (increased from 10 to 140 mA/cm²) and more stable emission than their unpatterned counterparts. The present technique may be widely applied in the fabrication of high-performance CNTs field-emitter arrays. Full article

We report for the first time the chromatographic study of n-alcohols (from methanol to butanol) adsorption on single walled carbon nanohorn (SWCNH). Using measured temperature dependence of adsorption isotherms (373–433 K) the isosteric adsorption enthalpy is calculated and compared with the data reported for a graphite surface. It is concluded that a graphite surface is more homogeneous, and the enthalpy of adsorption on SWCNHs at zero coverage correlates well with molecular diameter and polarizability, suggesting leading role of dispersive interactions, i.e., no heteroatoms presence in the walls of SWCNH structures. Next using modern DFT approach we calculate the energy of n-alcohols interactions with a graphene sheet and with a single nanocone finally proposing a more realistic—double nanocone model. Obtained results suggest alcohols entrapping between SWCNH with OH groups located toward nanocones ends, leading to the conclusions about very promising future applications of SWCNHs in catalytic reactions with participation of n-alcohols. Full article

Here, we consider the free vibration of a tapered beam modeling nonuniform single-walled carbon nanotubes, i.e., nanocones. The beam is clamped at one end and elastically restrained at the other, where a concentrated mass is also located. The equation of motion and relevant boundary conditions are written considering nonlocal effects. To compute the natural frequencies, the differential quadrature method (DQM) is applied. The influence of the small-scale parameter, taper ratio coefficient, and added mass on the first natural frequency is investigated and discussed. Some numerical examples are provided to verify the accuracy and validity of the proposed method, and numerical results are compared to those obtained from exact solution. Since the numerical results are in excellent agreement with the exact solution, we argue that DQM provides a simple and powerful tool that can also be used for the free vibration analysis of carbon nanocones with general boundary conditions for which closed-form solutions are not available in the literature. Full article

α″-Fe₁₆N₂ nanomaterials with a shape anisotropy for high coercivity performance are of interest in potential applications such as rare-earth-free permanent magnets, which are difficult to synthesize in situ anisotropic growth. Here, we develop a new and facile one-pot microemulsion method with Fe(CO)₅ as the iron source and tetraethylenepentamine (TEPA) as the N/C source at low synthesis temperatures to fabricate carbon-coated tetragonal α″-Fe₁₆N₂ nanocones. Magnetocrystalline anisotropy energy is suggested as the driving force for the anisotropic growth of α″-Fe₁₆N₂@C nanocones because the easy magnetization direction of tetragonal α″-Fe₁₆N₂ nanocrystals is along the c axis. The α″-Fe₁₆N₂@C nanocones agglomerate to form a fan-like microstructure, in which the thin ends of nanocones direct to its center, due to the magnetostatic energy. The lengths of α″-Fe₁₆N₂@C nanocones are ~200 nm and the diameters vary from ~10 nm on one end to ~40 nm on the other end. Carbon shells with a thickness of 2–3 nm protect α″-Fe₁₆N₂ nanocones from oxidation in air atmosphere. The α″-Fe₁₆N₂@C nanocones synthesized at 433 K show a room-temperature saturation magnetization of 82.6 emu/g and a coercive force of 320 Oe. Full article

This study aims to provide a computational algorithm which contributes to the understanding and implementation of carbon nanochimneys. The structure resembles a tube ending with an inverted funnel, with a connection region that uses non-hexagonal rings as defects in order to match the boundaries of the two linked nanostructures. They are important for applications such as thermal transport, gas storage, or separation. The algorithm is written in Python 3.7 and provides a .pdb file with the coordinates of all the atoms included in the system. The parameters that can be specified are the carbon nanotube dimensions, for either armchair or zigzag conformations, five levels of disclination for the carbon nanocone along with the base diameter of the latter. Full article

Hydrogen fuel cells rely on the purity of the hydrogen gas for maintaining a high performance. This study investigates a novel nanostructure design for its effectiveness in separating H₂ molecules from a mixture of gases containing H₂, CH₄, CO₂, N₂, CO and H₂O molecules using Molecular Dynamics simulations. Based on an open-ended (28, 0) rotating carbon nanotube with one carbon nanocone at each of its two extremes, this device is predicted through Molecular Dynamics simulations to be able to separate hydrogen from a gas mixture contained within. The nanocones were placed with their tips inside the nanotube and the size of the open channel created between the two was controlled to find a configuration that allows hydrogen to pass while restricting the other gases. Although in need of optimization, we find it capable of high selectivity and highlight captivating gas behavior insights to help advance rational gas separation device development. Full article

To design novel polymer materials with optimal properties relevant to industrial usage, it would seem logical to modify polymers with reportedly good functionality, such as polyimides (PIs). We have created a set of PI-based nanocomposites containing binary blends of CeO₂ with carbon nanoparticles (nanocones/discs or nanofibres), to improve a number of functional characteristics of the PIs. The prime novelty of this study is in a search for a synergistic effect amidst the nanofiller moieties regarding the thermal and the mechanical properties of PIs. In this paper, we report on the structure, thermal, and mechanical characteristics of the PI-based nanocomposites with binary fillers. We have found that, with a certain composition, the functional performance of a material can be substantially improved. For example, a PI containing SO₂-groups in its macrochains not only had its thermal stability enhanced (by ~20 °C, 10% weight loss up to 533 °C) but also had its stiffness increased by more than 10% (Young’s modulus as high as 2.9–3.0 GPa) in comparison with the matrix PI. In the case of a PI with no sulfonic groups, binary fillers increased stiffness of the polymer above its glass transition temperature, thereby widening its working temperature range. The mechanisms of these phenomena are discussed. Thus, this study could contribute to the design of new composite materials with controllable and improved functionality. Full article

We employed molecular dynamics simulations on the water solvation of conically shaped carbon nanoparticles. We explored the hydrophobic behaviour of the nanoparticles and investigated microscopically the cavitation of water in a conical confinement with different angles. We performed additional molecular dynamics simulations in which the carbon structures do not interact with water as if they were in vacuum. We detected a waving on the surface of the cones that resembles the shape agitations of artificial water channels and biological porins. The surface waves were induced by the pentagonal carbon rings (in an otherwise hexagonal network of carbon rings) concentrated near the apex of the cones. The waves were affected by the curvature gradients on the surface. They were almost undetected for the case of an armchair nanotube. Understanding such nanoscale phenomena is the key to better designed molecular models for membrane systems and nanodevices for energy applications and separation. Full article

Molecular dynamics (MD) simulation has been employed to study the wetting transitions of liquid gallium droplet on the graphene surfaces, which are decorated with three types of carbon nanopillars, and to explore the effect of the surface roughness and morphology on the wettability of liquid Ga. The simulation results showed that, at the beginning, the Ga film looks like an upside-down dish on the rough surface, different from that on the smooth graphene surface, and its size is crucial to the final state of liquid. Ga droplets exhibit a Cassie–Baxter (CB) state, a Wenzel state, a Mixed Wetting state, and a dewetting state on the patterned surfaces by changing distribution and the morphology of nanopillars. Top morphology of nanopillars has a direct impact on the wetting transition of liquid Ga. There are three transition states for the two types of carbon nanotube (CNT) substrates and two for the carbon nanocone (CNC) one. Furthermore, we have found that the substrates show high or low adhesion to the Ga droplet with the variation of their roughness and top morphology. With the roughness decreasing, the adhesion energy of the substrate decreases. With the same roughness, the CNC/graphene surface has the lowest adhesion energy, followed by CNT/graphene and capped CNT/graphene surfaces. Our findings provide not only valid support to previous works but also reveal new theories on the wetting model of the metal droplet on the rough substrates. Full article