Carbon Nanostructures Research Articles

Redirecting On-surface Cycloaddition Reactions in a Self-assembled Ordered Molecular Array on Graphite.

The synthesis of atomically precise carbon nanostructures in ultra-high vacuum has seen extensive progress on metal surfaces. However, this remains challenging on chemically inert surfaces. It is because the thermally activated C-C coupling encounters a severe "desorption problem" on weakly interacting substrates. In this study, we report an extraordinary [2+2]+[2+2] cycloaddition triggered by mild annealing (~210°C) in a highly ordered π-conjugated molecular array on graphite using scanning tunneling microscopy. In contrast to irregular dendritic fragments typically obtained on metal substrates, large supramolecular islands are observed here with cycloaddition products and other polymers over 30%, which are embedded as defective individuals or chains (grain boundaries). First-principles calculations reveal that the energy barriers of the multiple dehalogenation, dehydrogenation, and cycloaddition reactions are reduced by catalytic Fe atoms but remain energetically unfavorable. A distinct driving mechanism is proposed for redirecting the reactions on inert surfaces, where additional intermolecular coupling, steric hindrance, and/or interfacial interactions play significant roles. This study introduces a new paradigm for understanding on-surface synthesis on non-metal substrates.

Redirecting On‐surface Cycloaddition Reactions in a Self‐assembled Ordered Molecular Array on Graphite

The synthesis of atomically precise carbon nanostructures in ultra‐high vacuum has seen extensive progress on metal surfaces. However, this remains challenging on chemically inert surfaces. It is because the thermally activated C‐C coupling encounters a severe “desorption problem” on weakly interacting substrates. In this study, we report an extraordinary [2+2]+[2+2] cycloaddition triggered by mild annealing (~210°C) in a highly ordered π‐conjugated molecular array on graphite using scanning tunneling microscopy. In contrast to irregular dendritic fragments typically obtained on metal substrates, large supramolecular islands are observed here with cycloaddition products and other polymers over 30%, which are embedded as defective individuals or chains (grain boundaries). First‐principles calculations reveal that the energy barriers of the multiple dehalogenation, dehydrogenation, and cycloaddition reactions are reduced by catalytic Fe atoms but remain energetically unfavorable. A distinct driving mechanism is proposed for redirecting the reactions on inert surfaces, where additional intermolecular coupling, steric hindrance, and/or interfacial interactions play significant roles. This study introduces a new paradigm for understanding on‐surface synthesis on non‐metal substrates.

Multilevel Nitrogen-Doped Carbon Nanostructures through CoFe Alloy Integration for Trifunctional Electrocatalysis

Multilevel Nitrogen-Doped Carbon Nanostructures through CoFe Alloy Integration for Trifunctional Electrocatalysis

Influence of polypyrrole-derived nitrogen-doped carbon nanostructure morphology on the microbial composition of anodic biofilms and microbial fuel cell performance

Influence of polypyrrole-derived nitrogen-doped carbon nanostructure morphology on the microbial composition of anodic biofilms and microbial fuel cell performance

Molecularly engineered carbon nanostructures derived from Parthenium hysterophorus for ultralow detection of lead(ii) ions

Parthenium hysterophorus-derived molecularly engineered carbon nanostructures demonstrating high sensitivity and selectivity in the electrochemical sensing of lead(ii) ions.

Effect of electrochemical bromide doping on the performance of nitrogen-doped carbon nanostructures for oxygen reduction reaction

Effect of electrochemical bromide doping on the performance of nitrogen-doped carbon nanostructures for oxygen reduction reaction

Effect of carbon nanostructures on low carbon magnesia-carbon refractories manufactured using slip-casting as an alternative method

Effect of carbon nanostructures on low carbon magnesia-carbon refractories manufactured using slip-casting as an alternative method

The Role of Carbon in Lead-Acid Batteries: Applications, Challenges, and Future Opportunities

The incorporation of various forms of elemental carbon into lead-acid batteries has the potential to significantly enhance battery performance. Carbon materials are commonly used as additives to the negative active material, particularly to improve cycle life and charge acceptance under high-rate partial state-of-charge (HRPSoC) conditions, which are prevalent in hybrid and electric vehicles. Carbon nanostructures and composite materials may also offer similar benefits. However, the impact of carbon on the positive active material is generally more limited compared to its influence on the negative side. Additionally, carbon can serve as a mesh current collector for both negative and positive plates. This advanced technology boosts energy storage efficiency by increasing the battery’s specific energy and optimizing active mass utilization. Such batteries, featuring a more robust active mass structure, promise extended cycle life. Recently, another important application of carbon in secondary batteries is its use in supercapacitor electrodes, which can either replace the negative plate or be connected in parallel with the lead plate. These innovative approaches enhance overall battery efficiency by improving specific power and HRPSoC performance. Furthermore, integrating carbon-based technologies into the production of lead-acid batteries can significantly enhance their performance, giving them a competitive advantage over other battery systems. These advancements also hold substantial potential for delivering more environmentally friendly and cost-effective energy storage solutions.

Моделирование износа при трении качения с проскальзыванием

The paper views mathematical and numerical models of wear of elastomeric materials developed by the authors in dead rolling with sliding movement. When developing a mathematical model, classical ideas about the kinematic characteristics of a massive elastomeric tire rolling along the abrasive surface of the disc were used. To describe the intensity of wear, the model uses the concepts of wear formulated by D. Archard and modified in relation to the studied objects - rubber-based resin elastics SRI-3 and SRS-30–ARKM-15 rubbers reinforced with carbon nanostructures. The numerical implementation of the mathematical model is performed in the Matlab software package. In order to simplify the numerical calculation, it was decided to switch the rolling slip model to the pure sliding model. The choice of the integration step in time allowed to stabilize the instability of the solution. Thus, the numerical model examined sliding of an elastomeric cylinder along the abrasive surface of the disk at a speed equal to the sliding speed and varying the normal load. The finite element method (FEM) was used as a numerical calculation method. At a fixed depth of indentation, the verification of the developed model was carried out. According to the simulation results, the dependences of the wear intensity of an elastomeric material on the magnitude of specific pressures are obtained. A comparative analysis of the simulation results and the data obtained experimentally make it possible to determine the difference at the level of 20 percent, which may be due to the limitations of the model when thermal characteristics of the materials are not taken into consideration. Thus, the developed model has demonstrated its viability and will be further refined upon taking into account the identified limitations.

Carbon Nanostructures Derived from In Situ Grown ZIF Nanocages within Bacterial Cellulose for AC-Filtering Electrochemical Capacitors.

Electrochemical capacitors (ECs) offer superior specific capacitance for energy storage compared to traditional electrolytic capacitors but face limitations in alternating current (AC) filtering due to the need for balancing fast response and high capacitance. This study addresses these challenges by developing a freestanding nanostructured carbon electrode, derived from the rapid carbonization of bacterial cellulose (BC) embedded with zeolitic imidazolate framework 8 (ZIF-8) and in situ formed carbon nanotubes (CNTs). The electrode exhibits an exceptionally low area resistance of 9.8 mΩ cm2 and a high specific capacitance of 2.1 mF cm-2 at 120Hz, maintaining performance even at high frequencies. Stacking these electrodes enhances the capacitance to 5.3 mF cm-2, with the phase angle degrading to -74.4° at 120Hz; however, they retain a phase angle below -45° up to ≈50kHz, demonstrating excellent high-frequency performance. Furthermore, connecting three aqueous units in series as an integrated cell or utilizing organic electrolytes extends the voltage window to 2.4V, enhancing their suitability for high-voltage applications. Ripple voltage analysis under various loads and frequencies indicates effective filtering capabilities, highlighting the potential of these nanostructured ECs for next-generation electronic applications.

Mesoporous Carbon Composites Containing Carbon Nanostructures: Recent Advances in Synthesis and Applications in Electrochemistry.

Carbon nanostructures (CNs) are various low-dimensional allotropes of carbon that have attracted much scientific attention due to their interesting physicochemical properties. It was quickly discovered that the properties of CNs can be significantly improved by modifying their surface or synthesizing composites containing CNs. Composites combine two or more materials to create a final material with enhanced properties compared with their initial components. In this review, we focused on one group of carbon materials-composites containing CNs (carbon/CN composites), characterized by high mesoporosity. Particular attention was paid to the type of synthesis used, divided into hard- and soft-templating methods, the type of polymer matrix precursors and their preparation method, heteroatom doping, pore formation methods, and correlations between the applied experimental conditions of synthesis and the structural properties of the composite materials obtained. In the last part, we present an updated summary of the applications of mesoporous composites in energy storage systems, supercapacitors, electrocatalysis, etc. The correlations among porous structures of materials, heteroatom doping, and electrochemical or catalytic efficiency, including activity, selectivity, and stability, were also emphasized. To our knowledge, a single review has never summarized pyrolyzed mesoporous composites of polymer-CNs, their properties and applications in electrochemistry.

Tip-Induced 3D Printing on the Nanoscale with Field Emission Scanning Probes.

3D printing down to the nanoscale remains a significant challenge. In this paper, the study explores the use of scanning probes that emit low-energy electrons (<100eV) coupled with the localized injection and electron-induced decomposition of precursor molecules, for the precise localized deposition of 3D nanostructures. The experiments are performed inside the chamber of a scanning electron microscope (SEM), enabling the use of the in-built gas injector system (GIS) with gaseous naphthalene precursor for carbon deposition, as well as immediate inspection of the deposits by SEM. Substrate materials are planar fused silica with thin conductive coatings and non-planar copper wedges. After investigation of the deposition process parameters, various 2D and 3D carbon deposits are grown. Vertical nanowires several microns in length with a diameter <100nm are achieved and 3D deposits with a high degree of nanoscale branching are also obtained, presumably due to a charging effect. High aspect ratio carbon nanostructures such as those demonstrated here can be employed as miniaturized electrodes or field emitters. The tip-based approach presented thus paves the way toward 3D nanoscale printing of various materials and functional nanostructures.

Forecasting the Mass Activity of Platinum Anode Catalysts on Various Carbon Nanostructures in Direct Methanol Fuel Cells Using Machine Learning

Abstract Anode catalyst loading in direct methanol fuel cells (DMFC) is extremely high at around 4.5 mgPtRu/cm2, which increases cost and inhibits commercialization. Several carbon nanostructures, such as carbon nanotubes, graphene, mesoporous carbon, and carbon quantum dots, are used to support platinum as well as platinum with other metals and metal oxides to reduce the platinum content of catalysts. Optimizing the catalyst composition for DMFC requires extensive trial and error experiments due to the complex electrochemical and thermodynamic processes, which demands considerable time. We present here machine learning-aided models that correlate the composition of platinum-based catalysts on different carbon nanostructures with the mass activity of DMFC. Various machine learning techniques are employed to predict the mass activity of platinum-based catalysts using data from published literature. These models demonstrate a good level of predictive accuracy (R2&gt;0.85) with the available datasets and show that even basic models can provide reliable forecasts. The SHapley Additive Explanations (SHAP) summary plot reveals that graphene's weight fraction is the most significant feature among all carbon nanostructures, followed by the weight fractions of cobalt and platinum. Hence, machine learning has demonstrated significant effectiveness in predicting platinum's mass activity based on catalyst composition and process parameters.

Tuning Electronic Relaxation of Nanorings Through Their Interlocking.

Electronic and vibrational relaxation processes can be optimized and tuned by introducing alternative pathways that channel excess energy more efficiently. An ensemble of interacting molecular systems can help overcome the bottlenecks caused by large energy gaps between intermediate excited states involved in the relaxation process. By employing this strategy, catenanes composed of mechanically interlocked carbon nanostructures show great promise as new materials for achieving higher efficiencies in electronic devices. Herein, we perform nonadiabatic excited state molecular dynamics on different all-benzene catenanes. We observe that catenanes experience faster relaxations than individual units. Coupled catenanes present overlapping energy manifolds that include several electronic excited states spatially localized on the different moieties, increasing the density of states that ultimately improve the efficiency in the energy relaxation. This result suggests the use of catenanes as a viable strategy for tuning the internal conversion rates in a quest for their utilization for new optoelectronic applications.

Nanotechnology-Enhanced Controlled Release Systems in Topical Therapeutics

Topical and transdermal drug delivery are alternative routes for medications facing challenges like solubility, stability, and first-pass metabolism. However, conventional immediate-release dosage forms delivered topically have drawbacks, including poor penetration and high side ef-fects. Controlled-release nanoparticles offer a promising solution, improving drug permeation and providing controlled release. This review examines recent advances, challenges, and pro-spects of controlled-release nanoparticles for topical drug delivery. Various types of nanoparti-cles, including lipid nanoparticles, Nanoemulsions, nanoemulgels, cubosome liposomes, poly-meric nanoparticles, solid-lipid nanoparticles, lipid-polymer hybrid nanoparticles, and nanostructured lipid carriers, carbon nanotubes, nanocomposites, and protein nanoparticles have been explored for their ability to encapsulate drugs, prolong drug release, and enhance skin permeation as well as improve therapeutic outcomes. Studies have demonstrated the effective-ness of these nanoparticles in improving sustained and controlled-release topical delivery of a wide range of drugs, including poorly soluble, low degree of skin penetration, low stability, and drugs with low bioavailability and biological products. Despite their potential benefits, challeng-es such as scalability, reproducibility, and safety concerns remain. Future research should ad-dress these challenges and explore novel strategies to improve efficacy and safety by converging with microneedles and 3D nanoparticles. Ultimately, controlled-release nanoparticles have the potential to revolutionize dermatological and transdermal drug delivery, leading to improved therapeutic outcomes and patient care.

Enhanced oxygen evolution reaction via CuO@N-doped carbon nanostructures: a facile synthesis and electrocatalytic investigation

Enhanced oxygen evolution reaction via CuO@N-doped carbon nanostructures: a facile synthesis and electrocatalytic investigation

Preparation of N-rich Porous Carbon Nanomaterial

Abstract The incorporation of heteroatoms, such as N, B, P, and O can enhance the electrical, mechanical, and semiconducting properties of carbon materials. Recent studies suggest that doping with these heteroatoms can play a vital role in enhancing the performance of carbon materials for advanced technological applications. In this work, N-doped porous carbon nanomaterial has been developed from low-cost glucose and conducting polymer using hydrothermal carbonization and oxidative polymerization methods. A diamine polymer poly (para-phenylenediamine) has been chosen as the N-rich precursor during the synthesis of the material. FESEM image of the material reveals a coating of poly (para-phenylenediamine) onto the carbon nanostructure. EDS analysis shows a high N (17 wt.%) content of the material sample.

Robust quantum engineering of current flow in carbon nanostructures at room temperature

Robust quantum engineering of current flow in carbon nanostructures at room temperature

N, F Co-Doped Carbon Derived from Spent Bleaching Earth Waste as Oxygen Electrocatalyst Support.

Affordable nitrogen and fluorine co-doped carbon nanostructure was prepared from the hazardous industrial waste of edible oil refinery, spent bleaching earth (SBE), and used as raw material for obtaining high-performance non-noble metal bifunctional oxygen electrocatalysts. Waste SBE contains 35 % residue non-saturated oil as a carbon source and the assistance of montmorillonite (MMT) as the template. This study converts waste SBE into a fluorine-doped carbon nanostructure through a pyrolysis process followed by removing the aluminosilicate layers of the MMT by HF etching. Furthermore, the impregnation of the support with Co and Fe nitrates readily gives rise to N, F co-doped carbon (NFC) electrocatalysts, as confirmed by XPS analysis. Electrochemical results evidenced that the Co-NFC catalyst proved to be a valuable bifunctional competitor for oxygen reduction reaction and oxygen evolution reaction in alkaline media, showing activity in both reactions and superior stability compared with the Fe-NFC catalyst in accelerated tests. This work offers a straightforward, economical, and eco-friendly strategy for designing N, F co-doped carbon-based electrocatalysts for oxygen reactions in electrochemical devices.

Influence of expansion ratio and multilayered gradient structure on the electromagnetic interference shielding performance of lightweight poly (lactic acid)/carbon nanostructures composite foams

Influence of expansion ratio and multilayered gradient structure on the electromagnetic interference shielding performance of lightweight poly (lactic acid)/carbon nanostructures composite foams