Negatively Charged Hydrophobic Carbon Nano-Onion Interfacial Layer Enabling High-Rate and Ultralong-Life Zn-Based Energy Storage.

Zn-based electrochemical energy storage (EES) systems are attracting more attention, whereas their large-scale application is restricted by the dendrite and parasitic reaction-caused unstable Zn anodes. Herein, a negatively charged hydrophobic carbon nano-onion (CNO) interfacial layer is proposed to realize ultrastable and high-rate Zn anodes, enabling high-performance Zn-based EES. For the CNO interfacial layer, its hydrophobicity not only blocks active water but also reduces the Zn2+ desolvation barrier, and meanwhile, the negatively-charged CNO nanoparticles adsorb Zn2+ and repel SO4 2- to homogenize Zn2+ flux, accelerate Zn2+ desolvation and suppress the self-corrosion of Zn anodes. Besides, the conductive CNO interfacial layer increases the surface area for the Zn deposition to reduce local current density. Consequently, under the modulation of the CNO interfacial layer, Zn plating/stripping exhibits impressive reversibility with an average Coulombic efficiency of 99.4% over 800 cycles, and Zn anodes present significantly enhanced electrochemical stability and rate performance, whose operation lifetime exceeds 2000 h at 1 mA cm-2 and 350 h even at 10 mA cm-2 . Moreover, high-rate and ultralong-life Zn-ion hybrid supercapacitors are achieved with the CNO interfacial layer-modulated Zn anode and activated CNO cathode. This work provides new thinking in regulating the Zn deposition interface to realize high-performance Zn-based EES.

An Ultra-Low-Temperature Alternating Current Filter.

Traditional alternating current filter based on aluminum electrolytic capacitors (AECs) suffer from abrupt drop of filtering capability at ultra-low temperatures (≤-30 °C), which greatly hinders the reliable working of electronics at extremely cold conditions. Herein, an ultra-low-temperature alternating current (AC) filter for the first time enabled by high-frequency supercapacitor based on covalently bonded hollow carbon onion-graphene hybrid structure is reported. It is found that the covalent bonding junctions enable high electronic conductivity and efficient ion adsorption/desorption behavior in the hybrid structure. Moreover, the hybrid structure owns positive curvature and shallows pores for fast ion diffusion kinetics. Consequently, the supercapacitor exhibits a record short resistor-capacitor time constant (τRC ) of 0.098 ms at 120 Hz at room temperature. Combining with low-melting-point electrolyte, the supercapacitor possesses excellent filtering capability and can output stable direct current signal with low fluctuation coefficients in a temperature range of -50 to 0 °C. More interestingly, the filter presents high negative phase angle, low dissipation factor, short τRC , and high capacitance retention below -30 °C, whereas AEC cannot work properly owing to its phase angle<45°. This work realizes the fabrication of an ultra-low-temperature AC filter, which presents a critical step forward for promoting the development of ultra-low-temperature electronics.

A modified quick-easy-cheap-effective-rugged-and-safe method involving carbon nano-onions-based dispersive solid-phase extraction and dispersive liquid-liquid microextraction for pesticides from grapes.

A combination of modified quick easy cheap effective rugged and safe extraction approach with carbon nano-onions-based dispersive solid-phase extraction and dispersive liquid-liquid microextraction was developed for the extraction of several pesticides (diazinon, chlorpyrifos, tebuconazole, deltamethrin, permethrin, haloxyfop-methyl, penconazole, and cyhalothrin) from grape before their analysis by gas chromatography-flame ionization detection. In the extraction approach, an aliquot of grape sample is chopped and after separating its juice, the pesticides that remained in the refuse are extracted by the quick, easy, cheap, effective, rugged, and safe extraction method. The obtained acetonitrile phase is mixed with juice and the analytes are extracted by the carbon nano-onions-based dispersive solid-phase extraction. The analytes are concentrated using the microextraction procedure to obtain high enrichment factors. The results showed low limits of detection (0.5-1.6 ng/g) and quantification (1.8-5.4 ng/g) with satisfactory linearity of the calibration curves (determination coefficient, r2 ≥ 0.994). The precision of the developed method expressed as relative standard deviations was good (≤7.2%). The method provided high enrichment factors (350-410) and extraction recoveries (70-82%). Finally, seven grape samples were analyzed successfully.

Electrochemical Properties of Screen-Printed Carbon Nano-Onion Electrodes.

The properties of carbon nano-onions (CNOs) make them attractive electrode materials/additives for the development of low-cost, simple to use and highly sensitive Screen Printed Electrodes (SPEs). Here, we report the development of the first CNO-based ink for the fabrication of low-cost and disposable electrodes, leading to high-performance sensors. Achieving a true dispersion of CNOs is intrinsically challenging and a key aspect of the ink formulation. The screen-printing ink formulation is achieved by carefully selecting and optimising the conductive materials (graphite (GRT) and CNOs), the polymer binder, the organic solvent and the plasticiser. Our CNO/GRT-based screen-printed electrodes consist of an interconnected network of conducting carbon particles with a uniform distribution. Electrochemical studies show a heterogeneous electron transfer rate constant of 1.3 ± 0.7 × 10-3 cm·s-1 and a higher current density than the ferrocene/ferrocenium coupled to a commercial graphite SPEs. In addition, the CNO/GRT SPE can detect dopamine in the concentration range of 10.0-99.9 µM with a limit of detection of 0.92 µM (N = 3). They exhibit a higher analytical sensitivity than the commercial graphite-based SPE, with a 4-fold improvement observed. These results open up the possibility of using high-performing CNO-based SPEs for electrochemical applications including sensors, battery electrodes and electrocatalysis.

Water-Dispersible Candle Soot-Derived Carbon Nano-Onion Clusters for Imaging-Guided Photothermal Cancer Therapy.

Herein, water-dispersible carbon nano-onion clusters (CNOCs) with an average hydrodynamic size of ≈90 nm are prepared by simply sonicating candle soot in a mixture of oxidizing acid. The obtained CNOCs have high photothermal conversion efficiency (57.5%), excellent aqueous dispersibility (stable in water for more than a year without precipitation), and benign biocompatibility. After polyethylenimine (PEI) and poly(ethylene glycol) (PEG) modification, the resultant CNOCs-PEI-PEG have a high photothermal conversion efficiency (56.5%), and can realize after-wash photothermal cancer cell ablation due to their ultrahigh cellular uptake (21.3 pg/cell), which is highly beneficial for the selective ablation of cancer cells via light-triggered intracellular heat generation. More interestingly, the cellular uptake of CNOCs-PEI-PEG is so high that the internalized nanoagents can be directly observed under a microscope without fluorescent labeling. Besides, in vivo experiments reveal that CNOCs-PEI-PEG can be used for photothermal/photoacoustic dual-modal imaging-guided photothermal therapy after intravenous administration. Furthermore, CNOCs-PEI-PEG can be efficiently cleared from the mouse body within a week, ensuring their excellent long-term biosafety. To the best of the authors' knowledge, the first example of using candle soot as raw material to prepare water-dispersible onion-like carbon nanomaterials for cancer theranostics is represented herein.

Boron-Doped Polygonal Carbon Nano-Onions: Synthesis and Applications in Electrochemical Energy Storage.

Doping of carbon nanostructures with heteroatoms, such as boron or nitrogen, is one of the most effective ways to change their properties to make them suitable for various applications. Carbon nano-onions (CNOs) doped with boron (B-CNOs) were prepared by annealing (1650 °C) nanodiamond particles (NDs) under an inert He atmosphere in the presence of B. Their physicochemical properties were measured using transmission (TEM) and scanning (SEM) electron microscopy, X-ray photoelectron spectroscopy (XPS), 10 B and 11 B solid-state magic-angle spinning (MAS) NMR spectroscopy, X-ray powder diffraction (XRD), Raman spectroscopy, porosimetry, and differential-thermogravimetric analyses (TGA-DTG). These properties were systematically discussed for the undoped and B-doped CNO samples. The amount of substitutional B in the CNO samples varied from 0.76 to 3.21 at. %. The TEM, XRD, and Raman analyses revealed that the increased amount of B doping resulted in decreased interlayer spacing and polygonization of the structures, which in turn led to their unusual physicochemical properties. All synthesized materials were tested as electrodes for electrochemical capacitors. The B-CNOs with low concentration of doping agent exhibited higher reversible capacitances, mainly owing to the formation of hydrophilic polygonal nanostructures and higher porosity.

Prediction of frequency band gaps in one-dimensional endohedral fullerene and carbon nano-onion chains.

CONTEXT: Acoustics have always played a central role in contemporary engineering, especially in the fields of communication, sensing, and even in more extraordinary applications such as non-invasive high-intensity focused ultrasound surgery. The rapid development of nano-scale-based technologies makes imperative the need for novel acoustic devices that take advantage of nanomaterials as well as their extraordinary physical properties. The successful design of such acoustic components requires the implementation of efficient nanostructures accompanied by fast and accurate modeling. Here, endohedral fullerene and carbon nano-onion one-dimensional nano-chains are explored as possible candidate nanodevices that generate unique frequency band gaps. METHODS: The wave propagation in chains of fullerene-based molecules is predicted by representing them as infinite one-dimensional mass-in-mass chains properly assembled by the use of springs whose coefficients are expressed according to the van der Walls (vdW) atomistic interactions. Based on Bloch's theorem, interesting elastic wave dispersion curves are obtained and illustrated, characterized by distinctive frequency ranges that waves cannot propagate, revealing the unique vibroacoustic behavior of the proposed nano-systems.

Preparation of a Highly Sensitive Electrochemical Aptasensor for Measuring Epirubicin Based on a Gold Electrode Boosted with Carbon Nano-Onions and MB.

Epirubicin is prescribed as an essential drug for treating breast, prostate, uterine, and gastrointestinal cancers. It has many side effects, such as heart failure, mouth inflammation, abdominal pain, fever, and shortness of breath. Its measurement is necessary by straightforward and cheap methods. The application of aptamer-based electrochemical sensors is accounted as a selective option for measuring different compounds. In this work, a thiol-modified aptamer was self-assembled on the surface of the gold electrode (AuE) boosted with carbon nano-onions (CNOs), and coupled with methylene blue (MB) as an electroactive tracker to achieve a sensitive and selective aptasensor. In the absence of the epirubicin, CNOs binds to the aptamer through a π-π interaction enhancing the MB electrochemical signal. When epirubicin binds to the aptamer, the adsorption of CNOs and MB to the aptamer is not well established, so the electrochemical signal is reduced, consequently, the epirubicin value can be measured. The prepared aptasensor demonstrated an excellent sensitivity with a curve slope of 0.36 µI/nM, and 3 nM limit of detection in the linear concentration range of 1-75 nM. The prepared aptasensor was accurately capable of measuring epirubicin in blood serum samples.

Insights into tribofilm formation on Ti-6V-4Al in a bioactive environment: Correlation between surface modification and micro-mechanical properties.

Ti-6Al-4V has been used as a surgical implant material for a long time because of its combination of strength, corrosion resistance and biocompatibility. However, there remains much that is not understood about how the surface reacts with the environment under tribocorrosion conditions. In particular, the conditions under which tribofilms form and their role on friction and wear are not clear. To evaluate the complicated nature of the dynamic surface microstructural changes on the wear track, high resolution transmission electron microscopy (TEM), scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) have been used to characterise the structure and chemical composition of the tribofilm. Detailed analysis of the formation and structure of the tribofilm and the metal surface deformation behaviour were studied as a function of applied potential and the role of proteins in the lubricant. For the first time, graphitic and onion-like carbon structures from wear debris were found in the testing solution. The presence of carbon nanostructures in the tribocorrosion process and the formation of the tribofilm leads to an improved tribocorrosion behaviour of the system, in particular a reduction in wear and friction. A detailed, quantitative, analysis of surface deformation was undertaken, in particular, the geometrically necessary dislocation (GND) density was quantified using precession electron diffraction (PET). A clear correlation between applied potential, tribofilm formation and the surface strain was established. STATEMENT OF SIGNIFICANCE: The formation of tribofilm and microstructure modification of the Ti-6Al-4V surface during tribocorrosion in a physiological environment is not fully understood. In particular, the correlation between microstructural changes and electrochemical conditions is not clear. This study presents a detailed investigation of the structure and chemical composition of tribofilms at the nanoscale during tribocorrosion tests in simulated body fluid and gives a detailed and quantitative description of the evolved surface structure. A clear correlation between applied potential, tribofilm formation and the surface strain was established. Moreover, particular attention is paid to the wear debris particles captured from the lubricating solution, including nanocarbon onion structures. The implications for tribocorrosion of the alloy in its performance as an implant are discussed.

Carbon/iron by-product from catalytic methane decomposition as recyclable Fenton catalyst for pollutant degradation.

Direct catalytic decomposition of methane (CDM) has been studied as a possible emission-free hydrogen production route for over 100 years. However, the high cost of catalyst regeneration limits its practical applications. Here, we demonstrate that the solid by-product from CDM using Fe ore catalysts comprising carbon nano onions encapsulated with magnetic Fe cores (Fe@C) can serve as efficient and recyclable Fenton catalysts for pollutant degradation. Fe@C/H2O2 has better performance than FeSO4/H2O2 at similar Fe concentrations and can be used to decompose various pollutants. Mechanistic studies reveal that graphitic carbon layers and encapsulated Fe0 contribute to their high catalytic activity. Further, Fe@C can be easily recovered from an aqueous solution and reused due to the encapsulated magnetic Fe particles. Over three reused cycles, Fe@C/H2O2 only yields 1/8 of Fe sludges compared to FeSO4/H2O2, significantly reducing Fe sludge treatment costs. Overall, Fe@C demonstrates excellent application potentials in water and wastewater treatment, making H2 production via CDM economically more viable.

In Vitro and In Vivo Biocompatibility of Boron/Nitrogen Co-Doped Carbon Nano-Onions.

Boron/nitrogen, co-doped, carbon nano-onions (BN-CNOs) have recently shown great promise as catalysts for the oxygen reduction reaction, due to the improved electronic properties imparted by the dopant atoms; however, the interactions of BN-CNOs with biological systems have not yet been explored. In this study, we examined the toxicological profiles of BN-CNOs and oxidized BN-CNOs (oxi-BN-CNOs) in vitro in both healthy and cancer cell lines, as well as on the embryonic stages of zebrafish (Danio rerio) in vivo. The cell viabilities of both cell lines cells were not affected after treatment with different concentrations of both doped CNO derivatives. On the other hand, the analysis of BN-CNOs and oxidized BN-CNO interactions with zebrafish embryos did not report any kind of perturbations, in agreement with the in vitro results. Our results show that both doped CNO derivatives possess a high biocompatibility and biosafety in cells and more complex systems.

Linking the Defective Structure of Boron-Doped Carbon Nano-Onions with Their Catalytic Properties: Experimental and Theoretical Studies.

Defects are widely present in nanomaterials, and they are recognized as the active sites that tune surface properties in the local region for catalysis. Recently, the theory linking defect structures and catalytic properties of nanocatalysts has been most commonly described. In this study, we prepared boron-doped carbon nano-onions (B-CNOs) by applying an annealing treatment of ultradispersed nanodiamond particles and amorphous boron. These experimental conditions guarantee doping of CNOs with boron atoms in the entire carbon nanostructure, thereby ensuring structural homogeneity. In our research, we discuss the correlations between defective structures of B-CNOs with their catalytic properties toward SO2 and tert-butanol dehydration. We show that there is a close relationship between the catalytic properties of the B-CNOs and the experimental conditions for their formation. It is not only the mass of the substrates used for the formation of B-CNOs that is crucial, that is, the mass ratio of NDs to amorphous B, but also the process, including temperature and gas atmosphere. As it was expected, all B-CNOs demonstrated significant catalytic activity in HSO3- oxidation. However, the subsequent annealing in an air atmosphere diminished their catalytic activity. Unfortunately, no direct relationship between the catalytic activity and the presence of heteroatoms on the B-CNO surface was observed. There was a linear dependence between catalytic activity and Raman reactivity factors for each of the B-CNO materials. In contrast to SO2 oxidation, the B-CNO-a samples showed higher catalytic activity in tert-butanol dehydration due to the presence of Brønsted and Lewis acid sites. The occurence of three types of boron-Lewis sites differing in electron donor properties was confirmed using quantitative infrared spectroscopic measurements of pyridine adsorption.

Laser-Induced Modification of Hydrogenated Detonation Nanodiamonds in Ethanol.

Apart from the frequently used high-temperature annealing of detonation nanodiamonds (DNDs) in an inert environment, laser irradiation of DNDs in a liquid can be effectively used for onion-like carbon (OLC) formation. Here, we used fully de-aggregated hydrogenated DNDs (H-DNDs) dispersed in ethanol, which were irradiated for up to 60 min using a 532 nm NdYAG laser with an energy of 150 mJ in a pulse (5 J/cm2) at a pulse duration of 10 ns and a repetition rate of 10 Hz. We investigated the DND surface chemistry, zeta potential, and structure as a function of laser irradiation time. Infrared spectroscopy revealed a monotonical decrease in the C-Hx band intensities and an increase of the C-O and C=O features. Transmission electron microscopy (TEM) revealed the formation of OLC, as well as a gradual loss of nanoparticle character, with increasing irradiation time. Surprisingly, for samples irradiated up to 40 min, the typical and unchanged DND Raman spectrum was recovered after their annealing in air at 450 °C for 300 min. This finding indicates the inhomogeneous sp3 to sp2 carbon transformation during laser irradiation, as well as the insensitivity of DND Raman spectra to surface chemistry, size, and transient structural changes.

Evaluation of the Covalent Functionalization of Carbon Nano-Onions with Pyrene Moieties for Supercapacitor Applications.

Herein, we report the surface functionalization of carbon nano-onions (CNOs) through an amidation reaction that occurs between the oxidized CNOs and 4-(pyren-4-yl)butanehydrazide. Raman and Fourier transform infrared spectroscopy methods were used to confirm the covalent functionalization. The percentage or number of groups in the outer shell was estimated with thermal gravimetric analysis. Finally, the potential applications of the functionalized CNOs as electrode materials in supercapacitors were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. Functionalization increased the specific capacitance by approximately 138% in comparison to that of the pristine CNOs, while acid-mediated oxidation reduced the specific capacitance of the nanomaterial by 24%.

In Situ Oxygenic Nanopods Targeting Tumor Adaption to Hypoxia Potentiate Image-Guided Photothermal Therapy.

Tumor adaption to hypoxic stress not only plays a crucial role in tumor malignancy but also can protect cancer cells from therapeutic interventions. Hence, therapeutic strategies attenuating tumor hypoxia in conjunction with conventional therapies may be an ideal approach. Here, we report the application of in situ oxygenic carbon nano-onion (CNO)/manganese oxide nanopods (iOCOMs) as novel theranostic photothermal transducers to neutralize the oncogenic influence of the hypoxic tumor microenvironment (TME). The developed onion-ring-shaped carbon nanoparticles or carbon nano-onions (CNOs) and iOCOM nanopods (CNO embedded in MnO2 nanosheets) were biologically stable and nontoxic and showed photothermal activity under near-infrared laser irradiation (808 nm). In addition, iOCOM assisted in the dismutation of hydrogen peroxide (H2O2), a potentially toxic reactive oxygen species that is secreted excessively by cancer cells in the hypoxic TME, resulting in in situ oxygenation and repolarization of the hypoxic TME to normoxia. The manganese ions released from iOCOM during the catalysis of H2O2 assisted in TME-responsive T1 magnetic resonance imaging (MRI). The in situ oxygenation by iOCOM in the hypoxic TME downregulated the secretion of hypoxia-inducible factor 1-α, which subsequently interfered with the cancer cell proliferation, favored tumor angiogenesis, and most importantly prevented metastatic epithelial-to-mesenchymal transition of tumor cells. Collectively, this work presents a new paradigm for antitumor strategies by targeting the tumor adaption to hypoxia in combination with photothermal therapy.

Carbon Nano-onions: A Valuable Class of Carbon Nanomaterials in Biomedicine.

The development of nanoscale materials is an important area of research as it provides access to materials with unique properties that can be applied to improve quality of life. Multi-layer fullerenes, also known as carbon nano-onions (CNOs) are an exciting class of nanostructures which show great versatility and applicability. They find applications in several fields of technology and biomedicine. This review highlights the potential advantages of CNOs for biomedical applications, which include but are not limited to bioimaging and sensing. Their good biocompatibility renders them promising platforms for the development of novel healthcare devices.

Sulfur Doping: Unique Strategy To Improve the Supercapacitive Performance of Carbon Nano-onions.

Recently, enhancement of the energy density of a supercapacitor is restricted by the inferior capacitance of negative electrodes, which impedes the commercial development of high-performance symmetric and asymmetric supercapacitors. This article introduces the in situ bulk-quantity synthesis of hydrophilic, porous, graphitic sulfur-doped carbon nano-onions (S-CNO) using a facile flame-pyrolysis technique and evaluated its potential applications as a high-performance supercapacitor electrode in a symmetric device configuration. The high-surface wettability in the as-prepared state enables the formation of highly suspended active conducting material S-CNO ink, which eliminates the routine use of binders for the electrode preparation. The as-prepared S-CNO displayed encouraging features for electrochemical energy storage applications with a high specific surface area (950 m2 g-1), ordered mesoporous structure (∼3.9 nm), high S-content (∼3.6 at. %), and substantial electronic conductivity, as indicated by the ∼80% sp2 graphitic carbon content. The in situ sulfur incorporation into the carbon framework of the CNO resulted in a high-polarized surface with well-distributed reversible pseudosites, increasing the electrode-electrolyte interaction and improving the overall conductivity. The S-CNOs showed a specific capacitance of 305 F g-1, an energy density of 10.6 W h kg-1, and a power density of 1004 W kg-1 at an applied current density of 2 A g-1 in a symmetrical two-electrode cell configuration, which is approximately three times higher than that of the pristine CNO-based device in a similar electrochemical testing environment. Even at 11 A g-1, the S-CNO||S-CNO device rendered an energy density (6.1 W h kg-1) at a deliverable power density of 5.5 kW kg-1, indicating a very good rate capability and power management during peak power delivery applications. Furthermore, it showed a high degree of electrochemical reversibility with excellent cycling stability, retaining ∼95% of its initial capacitance after more than 10 000 repetitive charge-discharge cycles at an applied current density of 5 A g-1.

Nanoforest: Polyaniline Nanotubes Modified with Carbon Nano-Onions as a Nanocomposite Material for Easy-to-Miniaturize High-Performance Solid-State Supercapacitors.

This article describes a facile low-cost synthesis of polyaniline nanotube (PANINT)⁻carbon nano-onion (CNO) composites for solid-state supercapacitors. Scanning electron microscopic (SEM) analyses indicate a uniform and ordered composition for the conducting polymer nanotubes immobilized on a thin gold film. The obtained nanocomposites exhibit a brush-like architecture with a specific capacitance of 946 F g-1 at a scan rate of 1 mV s-1. In addition, the nanocomposites offer high conductivity and a porous and well-developed surface area. The PANINT⁻CNO nanocomposites were tested as electrodes with high potential and long-term stability for use in easy-to-miniaturize high-performance supercapacitor devices.

A Review of Carbon Nanomaterials' Synthesis via the Chemical Vapor Deposition (CVD) Method.

Carbon nanomaterials have been extensively used in many applications owing to their unique thermal, electrical and mechanical properties. One of the prime challenges is the production of these nanomaterials on a large scale. This review paper summarizes the synthesis of various carbon nanomaterials via the chemical vapor deposition (CVD) method. These carbon nanomaterials include fullerenes, carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene, carbide-derived carbon (CDC), carbon nano-onion (CNO) and MXenes. Furthermore, current challenges in the synthesis and application of these nanomaterials are highlighted with suggested areas for future research.

Curvature-Induced Metal-Support Interaction of an Islands-by-Islands Composite of Platinum Catalyst and Carbon Nano-onion for Durable Oxygen Reduction.

Geometry of carbon supports significantly affected electrochemical durability of Pt/C (platinum electrocatalyst supported by carbon) for oxygen reduction reaction (ORR). Carbon nano-onion (CNO) was used as the support, which is characterized by its nanosize (similar to Pt size) and high curvature. Superior ORR durability was guaranteed by Pt/CNO due to (1) its islands-by-islands configuration to isolate each Pt nanoparticle from its neighbors by CNO particles; (2) highly tortuous void structure of the configuration to suppress Ostwald ripening; and (3) the curvature-induced strong interaction between CNO and Pt. The finding that highly curved carbon surface encourages electron donation to catalysts was first reported.