Carbon Trends最新文献

Floating catalyst chemical vapor deposition (FCCVD) enables ultrafast synthesis of CNTs and other 1D nanoparticles and their direct assembly as macroscopic solids. The chalcogen growth promotor in FCCVD produces high aspect ratio CNTs that can aggregate in the gas phase and form an aerogel which can be continuously spun as macroscopic fibres or sheets. We study the role of sulphur in controlling CNT morphology and aggregation by synthesising CNTs under a wide range of S/C ratios (0.001 to 5 wt.%) and determining their diameter and length distributions, number concentration and form of aggregation. Increasing S/C ratio in this range increases mean number of CNT walls from 1 to 8, decreases mean length from 34 to 6 µm, but CNT number concentration remains approximately constant at 8 × 10⁸#/cm³. Assuming growth within the first 3 cm of the reactor, longitudinal growth rate spans 1.5- 6.5 µm/s for the different CNT morphologies, but with similar mass throughput of 700 attogram/catalyst. This indicates the amount of carbon reaching the catalyst and solidifying as CNT remains constant regardless of the sulphur available in the catalyst, suggesting the rate limiting process is not at the catalyst/promoter interface but instead in the transport of carbonaceous active precursors to the catalyst, either due to their diffusion in the gas phase or decomposition kinetics. The CNTs produced range from polymer-like, which readily bundle and form aerogels, to rod-like that do not. We include aerogelation “phase diagrams” for different CNT concentrations, aspect ratios and CNT bending stiffness.

A very simple electrochemical top-down procedure was employed to obtain pure graphene quantum dots (GQDs) in water and using only graphite as carbonaceous precursor. The graphitic structure of the GQDs has been clearly observed by high-resolution transmission electronic microscopy (HRTEM). Then, the synthesis of N-doped GQDs was allowed by the addition of ammonia in the solution. The nitrogen doping was plainly evidenced by X-ray photoelectron (XPS) and Raman spectroscopies. The role of the electrolytic solution employed during the synthesis has been also discussed. Finally, these N-doped and non-doped GQDs were further used to prepare hybrids by grafting them onto ZnO semi-conductors, and their photocatalytic properties towards water-splitting were investigated. Interestingly, a very important enhancement of the amount of dihydrogen produced was observed with N-doped GQDs, compared to ZnO alone or to hybrids prepared with non-doped GQDs.

Carbon nanoparticles are well-characterized as nanotubes, nano diamonds, graphene and carbon dots. Their unique properties present promising applications in nanomedicine, including drug delivery systems. However, the cell-damaging effect of carbon-based nanoparticles remains elusive. Studies on carbon-caused cell deaths are contradictory, which makes it challenging to claim their precise nature, mechanisms, and harmful dosage. Moreover, previous findings showed that immune cells are the most susceptible cells to carbon nanoparticle treatment, where cell viability differs depending on cell culture and treatment specificities. Considering the shortage of topic-specific summarized data and rising interest in carbon nanomaterials, the present review article focuses on the cytotoxicity of carbon, in terms of cell viability, and types of cell deaths induced by carbon nanoparticles.

In this study, six bimetallic rare earth (RE = La, Ce, Pr, Nd, Sm, Eu) cobalt nitrogen doped carbon nanotubes (RECo-NCNTs) were synthesized with g-C₃N₄ derivative method. These RECo-NCNTs were characterized by SEM, BET, XPS, XRD and Raman. In addition, their catalytic performances for oxygen reduction reaction (ORR) had also been tested. The introduction of rare earths did not destroy the structure of nanotubes but apparently change their ORR performances. The PrCo-NCNTs showed the significant improvement in catalytic ability for ORR (onset potential of 0.95 V and half-wave potential of 0.79 V), which is very close to that of commercial 20 % Pt/C. Moreover, PrCo-NCNTs exhibits an excellent catalytic stability (no activity decay after 10000st cycles) and an outstanding methanol toxic tolerance. Assembled in metal–air batteries (Zn-air, Al-air and Mg-air), the PrCo-NCNTs electrode also presents high power densities and discharge voltages.

A high mobility of charge carriers and a low sheet resistance in graphene are the key indicators of its quality and applicability in electronic devices. In turn, the mobility of charge carriers in graphene is determined by graphene film smoothness. The electron scattering on structure defects of graphene film (wrinkles and grain boundaries) strongly affects the charge carrier mobility. In this work a simple and ultrafast approach for synthesis of graphene monolayer with the controllable smoothness and wrinkle density onto a resistively heated copper foil is presented. The method is a cold-wall chemical vapor deposition from methane. The fast synthesis of graphene with a full process cycle of 3 min is demonstrated. The structural defect density of polycrystalline graphene is optimized by appropriate combinations of methane concentration in the chamber and duration of synthesis process. Under the lower concentration of methane with the longer synthesis time the lower defect density in graphene appeared. The increase of process time from 30 s up to 10 min (under the decrease of methane concentration from 4.5 % to 0.36 %, respectively) leads to increase of average distance between wrinkles in graphene film from 6 µm to 35 µm. А charge carrier mobility as high as 2170 cm²V⁻¹s⁻¹ and a sheet resistance as low as 318 Ohm/□ under the lowest wrinkle density are measured for graphene polycrystalline monolayer deposited onto SiO₂ substrate.

This study presents a sustainable and versatile approach to synthesize graphene-like structures from bamboo waste for application in photoelectrochemical (PEC) devices. Due to its high cellulose content, bamboo, a locally available and renewable resource, is a perfect precursor for producing graphene-like materials. The synthesis process involves bamboo waste pyrolysis, followed by treatments with different solvents: ultrapure water (UPW), NaOH, and green tea extract. Characterization techniques confirmed the successful transformation of bamboo waste into carbon-rich, graphene-like materials with varying surface properties. The electrochemical characterization showed that the graphene-like materials could transfer electrons very well with a high current response compared to charcoal as a precursor. PEC evaluations revealed their potential as photoanodes, exhibiting efficient light absorption and charge carrier separation. This research emphasizes the significance of bamboo waste as a valuable precursor for eco-friendly graphene-like materials, offering a sustainable pathway for developing efficient PEC devices and green energy technologies.

In-situ transmission electron microscopy has evolved to be a unique technique to study process dynamics down to the atomic scale. Here, we show that in-situ Joule heating of carbon nanofilms facilitates the investigation of the nucleation, annealing, diffusion and evaporation of PtSi nanoparticles in a controlled way. The nanoparticles form from Pt-based hydrocarbon molecules and silicon oxide present on the amorphous carbon nanofilm. The in-situ transmission electron microscopy approach permits shedding light on the interaction between the nanoparticles and the carbon support, crucial information when aiming for stable catalytic applications. The method is versatile, allows reaching very high temperatures and could be applied to study many different combinations of bimetallic and even multimetallic high-entropy alloy nanoparticles.

Under this study, a straightforward method for producing clay-modified silico-graphitic carbon (CGSGC) was developed and applied to create CGSGC/epoxy coatings for carbon steel (CS). The CGSGC was synthesized using a mixture of 25 % pond clay, and 75 % remnant agricultural biomass by mass via pyrolysis route. The aim was to evaluate the barrier and anti-corrosion properties of these coatings. The results demonstrated that adding 0.1 wt.% of CGSGC in the epoxy (EP) matrix enhanced its anti-corrosion inhibition capabilities by 99.8 % when compared with standard EP coating. The 0.1 wt.% CGSGC/EP mixed coating also exhibited robust hydrophobicity with WCA of 142.2° and thermal stability up to 250 °C with 2–3 % coating weight reduction. The microhardness of the optimized sample shows a 59.18 % improvement compared to standard EP coating. SEM images revealed improved EP compactness and reduction in microstructural defects (holes and cracks), with the incorporation of 0.1 wt.% CGSGC. 3D profilometry showed a smoother surface for the 0.1 wt.% CGSGC/EP coating. Similar such materials, while being abundantrly and renewably available, can be a safer alternative to conventional hazardous chemicals for protecting carbon steel from corrosion; not to mention the carbon credit benefits they entail.

The recent observation of possible granular superconductivity in highly oriented pyrolytic graphite (HOPG) has attracted significant research interest. Here we report a novel investigation on the structural-properties of exfoliated-HOPG. We investigated two types of exfoliation methods, involving either a full (method-1) or partial (method-2) contact between adhesive tape and the main HOPG. Structural characterization was obtained by employing X-ray diffraction (XRD), Raman spectroscopy and electron microscopy (SEM). In particular, Raman point and mapping spectroscopy revealed significant structural-transitions from ABA (Bernal) to ABC (rhombohedral) stacking (stacking-faults), in those samples obtained with the method-2. Interestingly, strained regions exhibiting structural-deformations with a ridge-like morphology were reproducibly identified. The acquired Raman-spectra revealed a local enhancement of the D and D’ bands-intensity together with contributions arising from Electronic Raman Scattering (ERS) across the band-gap of rhombohedral-graphite, at middle (∼1870 cm⁻¹) and high (∼ 2680 cm⁻¹) frequency. HRTEM of the samples produced with the method-2 allowed also for the identification of local-coexistence of ripplocation-like defects with moiré superlattices, an indicator of non-uniform c-axis configuration.

In the realm of advancing energy storage technologies, the efficacy of natural biomass sources in mitigating environmental constraints has gained prominence. This study delves into the evolving landscape of energy storage devices, specifically batteries, super-capacitors, and the nascent domain of zinc-ion hybrid super-capacitors (ZIHSC). The focus centers on biomass-derived highly activated carbon, a burgeoning field of research esteemed for its diversity, environmental compatibility, distinctive structural attributes, and unique surface characteristics. This investigation presents a comparative analysis of activated carbons derived from ground nutshell (GS) in the context of ZIHSC applications. Emphasis is placed on the significance of a straightforward biochar synthesis process and subsequent chemical activation. The activated biochar, denoted as GS-H₃PO₄ and synthesized using H₃PO₄, exhibits a discernibly higher Brunauer Emmett Teller (B.E.T.) surface area when juxtaposed with pre-carbonized ground nutshell (GS-Biochar).The ZIHSC cell incorporating GS-H₃PO₄ manifests noteworthy energy density metrics, registering at 50.28 Wh Kg⁻¹ (100 W Kg⁻¹) and 11 Wh Kg⁻¹ (2 kW Kg⁻¹). Additionally, it demonstrates a specific capacitance of 199 F g⁻¹ (2 mV s⁻¹). These findings underscore the promising potential of H₃PO₄-derived activated carbon in optimizing cathode performance for Zinc-ion hybrid super-capacitors. This study contributes to the growing understanding of biomass-derived materials, offering insights into the nuanced interplay between synthesis methods and electrochemical properties, crucial for advancing sustainable energy storage solutions.