Carbon Nanolayers Research Articles

Deposition and characterization of carbon nanotubes on porous silicon by PECVD

Nano porous silicon was achieved by electrochemical etching technique of current density 20 mA/cm 2 , 25% HF and etching time 15min. Carbon Nano layers have been deposited on PSi substrate by PECVD. XRD spectrum show that porous silicon has crystalline phase and becomes very broad after etching time, in addition, XRD spectrum for carbon layers show several peaks between (2θ=28.25-28.75) which belong to carbon nanotube and these peaks intensity increases with increasing of carbon thickness. Raman spectrum illustrates that peak position was at 516.32nm for porous silicon prepared at etching time 15 min.

A Conformal Carbon Nanolayer Coated Fe2 O3 Cocatalyst for the Promoted Activity of Plasma-Sputtered BiVO4 Photoanode.

To simultaneously improve the hole extraction ability of the BiVO4 photoanode and accelerate the surface reaction kinetics, herein, a carbon nanolayer conformally coated Fe2 O3 (C-Fe2 O3 ) as oxygen evolution catalyst (OEC) is loaded on the H2 plasma treated nanoporous BiVO4 (BVO(H2 )) surface by a hydrothermal reaction. It is found that the H2 plasma induced vacancies in BVO remarkably increases the conductivity, and the C-Fe2 O3 enables hole extraction from the bulk to the surface as well as efficient hole injection to the electrolyte. As a result, the C-Fe2 O3 /BVO(H2 ) photoanode achieves a photocurrent density of 4.4 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE) and an ABPE value of 1.5 % at 0.68 V vs. RHE, which are 4.8-fold and 13-fold higher than that of BVO photoanode, respectively.

Precise Characterization of CNF-Coated Microfibers Using Transmission Electron Microscopy

The synthesis and characterization of fibrous materials with a hierarchical structure are of great importance for materials sciences. Among this class of materials, microfibers of different natures coated with carbon nanofibers attract special interest. Such coating modifies the surface of microfibers, makes it rougher, and thus strengthens its interaction with matrices being reinforced by the addition of these microfibers. In the present work, a series of hierarchical materials based on carbon microfibers, basalt microfibers, and fiberglass cloth coated with up to 50 wt% of carbon nanofibers was synthesized via the catalytic chemical vapor deposition technique. The initial items were impregnated with an aqueous solution of nickel nitrate and reduced in a hydrogen flow. Then, the catalytic chemical vapor deposition process using C2H4 or C2H4Cl2 as a carbon source was carried out. A simple and cost-effective technique for the preparation of the samples of hierarchical materials for transmission electron microscopy examination was developed and applied for the first time. The proposed method of sample preparation for sequential TEM visualization implies an ultrasonic treatment of up to four samples simultaneously under the same conditions by using a special sample holder. As was found, the relative strength of carbon nanofibers coating the surface of microfibers decreases in the order of CNF/CMF > CNF/BMF > CNF/FGC. Two effects of the ultrasonic action on the carbon coating were revealed. First, strongly bonded carbon nanofibers undergo significant breakage. Such behavior is typical for carbon and basalt microfibers. Secondly, carbon nanofibers can be completely detached from the microfiber surface, as was observed in the case of fiberglass cloth. In the case of CNF/CMF material, the graphitized surface of carbon microfiber is coherent with the structure of carbon nanofiber fragments grown on it, which explains the highest adhesion strength of the carbon nanolayer coated on carbon microfibers.

Моделирование использования АСМ при исследовании полиуретановых образцов с карбонизированной поверхностью

One of the most important characteristics of polyurethane endoprostheses used in modern medical practice is the quality of their surface. As a rule, such products are coated with a special carbon-ized nanolayer to improve biocompatibility with living tissue. In terms of mechanical properties, these layers are not as flexible as polyurethane and are prone to brittle microdamage. Therefore, a reliable determination of the presence and distribution of microcracks in the nanocarbon layer on the surface of an endoprosthesis is an important factor for assessing the biocompatibility and pos-sible injury to living tissues in the contact zone. The article presents the results of computer simu-lation of an AFM probe contact interaction with polyurethane samples having a carbonized nano-coating. The main goal of the study was to find an answer to the question whether it is possible to determine the presence of microdamages in polyurethane hidden under a carbonized coating using atomic force microscopy, and to classify them. Obviously, their presence can significantly aggra-vate the damaging effect of surface cracks on living biological tissue during the deformation of an endoprosthesis. Three cases of local microdamages that can occur in such samples are considered: a) there is a vertical crack in the carbon nanolayer, no damage in polyurethane; b) a cohesive dam-age of polyurethane (a vertical crack) was added to the vertical crack in the nanolayer; c) an adhe-sive delamination between the layer and polyurethane (a horizontal crack) was added to the verti-cal crack in the nanolayer. Computer modeling has shown that using atomic force microscopy, it is possible to quite accurately determine the presence of microcracks in the surface carbon nanolayer, while microdamages of the polyurethane itself, hidden under it, have a much weaker effect on nanoindentation.

Influence of the type of substrate on the properties of carbon nanotubes layer studied by Raman spectroscopy

The development of nanomaterials technology allows to design a novel medical strategies, and could also be useful in the field of regenerative medicine. The paper presents a study on the functionalized multi-walled carbon nanotubes (MWCNTs-f) layers deposited by electrophoretic method (EPD) on the surfaces of two types of substrates: titanium (Ti) and stainless steel. SEM and EDS analyses confirm that incubation in a simulated body fluid (SBF) caused a formation of hydroxyapatite on the surface of the Ti/MWCNTs-f. Raman micro-spectroscopy was a method of choice to study presented materials. The MWCNTs-f layer on the surface of the titanium plate shows better layer order than the corresponding layer deposited on the stainless steel. The structure and ordering of the nanocarbon layer play a key role in the biological activity of the materials. This was confirmed by the incubation of the plates with deposited layer of carbon nanotubes in SBF. A titanium substrate with a MWCNTs-f layer supports the deposition of some components from the environment, while a stainless steel substrate promotes the formation of a carbon film that inhibits the deposition of certain components from the environment. A two-trace two-dimensional (2T2D) analysis confirmed a different effect of SBF on the MWCNTs-f layer depending on the type of substrate. The MWCNTs-f layer on titanium substrate seems to represent an interesting proposition for novel bioactive strategies.

Role of surface carbon nanolayer on the activation of flash sintering in tungsten carbide

Flash sintering has been recently successfully activated also in conductive ceramics like tungsten carbide (WC). The present work aims at understanding how the WC particles surface chemistry can influence the electrical properties of the material and play a fundamental role in the flash sintering phenomenon. An electrical contact resistance (ECR) model was developed to understand the role of resistive surface layers on the electrical behaviour of WC green compacts under different applied pressures during the initial stages of the processes. It is established that the large resistivity measured on green compacts can be attributed to the sole presence of an ultrathin carbon layer on the particles' surface. A carbon nanolayer with a thickness of about 1–2 nm, as detected by XPS and TEM analyses, is found to be responsible for the high resistance reached at the particles' contact points while evolving during the flash event. Flash sintering conditions can be achieved during the electrical resistance flash sintering (ERFS) process in WC nanoparticles covered by such carbon layer and independently of the presence of W oxides.

Bi@C sandwiched carbon nanolayers enables remarkable cyclability at high current density for lithium-ion batteries

Large designs are devoted to decrease the volume fluctuation and pulverization of bismuth anodes. However, further advances in cycling stability at higher current density remain challenging. Herein, we skillfully designed a unique sandwich structure composed of bismuth nanoparticles coated with carbon nanolamella (Bi@C) and carbon nanolayers (C NL) via a simple pyrolysis method. Benefiting from the synergistic effect of the unique interlayer hybrid structure, the Bi@C composite material has an interconnected electron transportation pathway, which effectively alleviates the volume expansion during alloying/dealloying and reduces the agglomeration of the Bi particles during cycling. In addition, the Bi@C embedded in the double carbon layers structure (Bi@C/C NL) not only serve as highly conductive networks for Li+, but also provide a large surface area for electrolyte penetration and storage, which will enhance the charge transfer reaction kinetics process. As a result, the Bi@C/C NL-700 anode revealed a superior capacity (427.5 mAh g−1 at 500 mA g−1 after 300 cycles), excellent long cycling stability (373 mAh g−1 at 3 A g−1 after 1500 cycles) and improved rate performance, outperforming the most reported Bi-based anode materials for lithium-ion batteries. This work will lay an experimental foundation for the rational design of high-performance anode materials in rechargeable batteries with layered hybrid structures.

Controllable N Doped in Carbon Nanolayers@Mo2C Nanodots as Electrocatalyst Boosts High‐Efficient Hydrogen Production

AbstractMo2C is one of the promising alternatives to the precious metal catalyst for hydrogen evolution reaction (HER). However, it is still challenging to prepare highly dispersed Mo2C and prevent nanoparticles (NPs) from sintering during high‐temperature carbonization. Herein, a strategy is proposed to realize dual purposes that confine the coalescence of Mo2C NPs and redistribute charge density by regulating N‐doped contents. As‐synthesized molybdenum carbide nanodots are well dispersed on the N‐doped carbon nanolayers, and the size of Mo2C is uniform and less than 5 nm. The HER tests reveal that as‐prepared Mo2C nanodots exhibit excellent electrocatalytic activity for HER and long‐term stability. Theory calculation proves that optimizing N doping amount can tune hydrogen adsorption free energies and redistribute charge density. The present study provides insight into the impact of nitrogen doped in C/Mo2C and also a synthetic route to achieve heteroatom doping and size control for the synthesis of nanocatalysts beyond Mo2C.

Carbon-based hole storage engineering toward ultralow onset potential and high photocurrent density of integrated SiC photoanodes

In the present work, we report the exploration of integrated photoanode based on SiC nanohole arrays with a rationally designed amorphous carbon nanolayer. The SiC nanoarrays are fabricated via anodic oxidation, and the carbon outlayers are introduced by chemical vapor deposition (CVD) process, respectively. In such case, the active materials of carbon outlayer coated SiC nanoarrays (SiC@C) and current collector of the unetched SiC wafer are established into a whole structure without interfaces, thus favoring the formation of integrated photoanode. It is verified that the coated carbon nanolayer acts as an efficient hole storage layer, which effectively drives the separation of photogenerated carriers. Consequently, the as-fabricated SiC@C photoanode exhibits excellent photoelectrochemical (PEC) water splitting properties with a high solar-to-hydrogen efficiency of 2.67%. Moreover, it delivers an ultralow onset potential of −0.049 V (vs. RHE) and a high photocurrent density of 5.0 mA/cm2 (1.23 V vs. RHE), superior to those of intrinsic SiC counterparts and most SiC nanostructures ever reported, implying their promising applications in the field of solar energy conversion.

001]-oriented LiMn0.6Fe0.4PO4/C nanorod microspheres contributing high-rate performance to olivine-structured cathode for lithium-ion battery

Recently, cathode materials for Li-ion batteries (LIBs) with high-voltage platforms have become a research hotspot. Olivine-structured LiMnPO4 has the advantage of 4.1 V voltage platform but also has been plagued by poor e-/Li+ conductivity. Here, we report a facile synthetic strategy to fabricate LiMn0.6Fe0.4PO4/C (LMFP) composite. Such composite is composed of [001]-oriented nanorods and assembled into dense microspheres. The [001]-oriented nanorod structure exhibits a shortened Li+ diffusion length resulting from a smaller dimensional size in the [010] direction. Meanwhile, the conductive carbon nanolayer is uniformly coated on the surface of LiMn0.6Fe0.4PO4 nanorods, which greatly improves the e- conductivity of the material. The [001]-oriented structure feature combined with improved e- conductivity contributes to the delivery of extraordinary rate capabilities (141.6 mAh/g at 10C) and remarkable cycling stabilities (97.8% retention rate after 300 cycles at 1C). Such rational-designed nanorod microspheres are good candidates for the next generation of olivine-structured cathode for high-rate, high-energy, and high-safety LIBs.

Flower-like NiCo2O4 nanoflake surface covered on carbon nanolayer for high-performance electro-oxidation of non-enzymatic glucose biosensor

The high porous nickel cobalt oxide flower-like nanoflake (NF) structured materials with (C/NiCo2O4-1 and C/NiCo2O4-2) and without (NiCo2O4) the presence of dopamine as a carbon source were synthesized by a simple hydrothermal method for non-enzymatic glucose sensing. The structural and morphological characteristics of as-synthesized materials were confirmed using transmission electron microscopy, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis. The transmission electron microscopy analysis of C/NiCo2O4-1 NF materials reveals that a flower-like structure of NiCo2O4 NF covered over the surface of carbon in the hybrid composite. The electrochemical properties of as-synthesized material were determined from cyclic voltammetry and chronoamperometry analysis. Among the NiCo2O4 NF, C/NiCo2O4-1 NF, and C/NiCo2O4-2 NF structured materials, the C/NiCo2O4-1 NF exhibits a remarkable electrochemical performance toward glucose oxidation with a high linear range (0.0001–15.28 mM), high-sensitivity (779.35 μA mM−1 cm−2), and ultra-low detection (86 μM). Moreover, the C/NiCo2O4-1 NF electrode indicates excellent recoveries of glucose in human blood serum samples. The obtained results illustrate that the good features of C/NiCo2O4-1 NF electrode materials have the potential to be used as a non-enzymatic glucose sensor.

Double-shell interphase design enabling suppressed side reactions for stable Si battery anode

Silicon (Si)-based anode is promising for the next-generation high-energy lithium-ion batteries due to the high capacity. However, it suffers parasitic side reactions between electrode and electrolyte in the initial cycle, which consumes abundant active lithium and makes it one of the limiting factors for the implementation of Si-based anodes. It is of vital importance to suppress the side reactions at the electrode interphase and improve the electrochemical/chemical stability. Here, we designed an ultrathin double-shell interphase structure (∼15 nm), consisting of an inner VO2 nanoshell and an outer C nanoshell. The inner VO2 nanolayer avoided the direct contact between active Si and electrolyte, and, thus, hindered the side reactions between them. The carbon nanolayer stabilized the VO2 layer mechanically and improved the electronic conductivity of the anode materials. Thus, a thin solid electrolyte interphase was formed on the as-designed Si@VO2@C surface, and high initial Coulombic efficiency (ICE) was realized. Notably, the Si@VO2@C electrode exhibited a high reversible capacity of 2300 mAh g−1 at 0.1 C and high ICE of 90.2%, which was about 18% higher than that of a pristine Si electrode. Also, the electrode displayed stable electrochemical cycling with high capacity retention of 84.8% for 100 cycles at 0.4 C. With 15 wt. % addition into the graphite, the hybrid electrode Si@VO2@C/graphite exhibited a high reversible charge capacity of 596 mAh g−1 and satisfactory cycling performance with high capacity retention of 83.8% at 100 mA g−1 under a high area capacity of 3.46 mAh cm−2, showing promise for the practical application.

Perforated nitrogen-rich graphene-like carbon nanolayers supported Cu-In catalyst for boosting CO2 electroreduction to CO

The combination of a powerful CO2-enriching carrier and robust active component provides a new idea for the construction of efficient catalysts for electrocatalytic CO2 reduction. Herein, novel perforated nitrogen-rich graphene-like carbon nanolayers (PNGC) are prepared from biomass derivatives, which promotes the oriented deposition of In-doped Cu2(OH)3(NO3) nanosheet patches. A robust Cu-In/PNGC composite catalyst is then obtained via simple in-situ electrochemical reduction. Unsurprisingly, Cu-In/PNGC exhibits a CO Faradaic efficiency (FECO) of 91.3% and a remarkable CO partial current density (jCO) of 136.4 mA cm−2 at a moderate overpotential of 0.59 V for electrocatalytic CO2 reduction reaction (CO2RR). DFT calculations and experimental studies indicate that the strong carrier effect of PNGC makes PNGC carried Cu-In nanosheets improved the adsorption capacity of CO2 gas, reconfigured electronic structure, and reduced free energy of key intermediate formation, thereby the CO2 activation and conversion are promoted.

Highly efficient removal of organic contaminants and hydroxylamine hydrochloride enhancement effect based on magnetic iron/nitrogen doped carbon nanolayer

Developing highly effective and environmental friendliness Fe-based catalysts have attracted increasing attention. Herein, novel nitrogen-doped carbon nanolayer with Fe0/Fe3C nano-particles (Fe@NCL-900) were innovatively fabricated by a simple solvent-free strategy, pyrolyzed the mixture of 4,6-dihydroxypyrimidine and ferric chloride hexahydrate under 900 ℃. In the presence of peroxymonosulface (PMS), Fe@NCL-900 could remove almost 100% Carbamazepine in 6 min with an amazing apparent first-order constant (kobs) as high as 0.733 min−1, about 72 and even 88 times higher than that of the commercial zero-valent iron and the traditional Fenton system, respectively, which was mainly ascribed to the synergistic effect of high graphite carbon and excellent reducing ability of Fe0. Moreover, high valent iron species (Fe (IV)) and four types of reactive oxygen species (ROS) including hydroxyl radical (•OH), sulfate radical (SO4•-), singlet oxygen (1O2), superoxide radical (O2•-) were detected to play a key role in Carbamazepine removal by electron paramagnetic resonance (EPR) and the radical quenching experiments. Interestingly, it was observed that the addition of hydroxylamine hydrochloride could effectively improve the production of more ROS and the first-order constant was enhanced by 7.6 times (5.593 min−1), completely different from the previous reports that hydroxylamine hydrochloride in high concentrations would inhibit the removal rate. Moreover, the magnetically separable catalyst possessed a wide pH range (2.0–10.0) and superior reusability. This study provides novel insights for manufacturing a promising Fe-based nitrogen-doped catalyst in practical wastewater treatment.

Improving electron and ion transport by constructing 3D graphene nanosheets sandwiched between porous carbon nanolayers produced from resorcinol-formaldehyde resin for high-performance supercapacitor electrodes

Improving electron and ion transport by constructing 3D graphene nanosheets sandwiched between porous carbon nanolayers produced from resorcinol-formaldehyde resin for high-performance supercapacitor electrodes

Si3N4 nanowires@pyrolytic carbon nanolayers coupled with hydroxyapatite nanosheets as reinforcement for carbon matrix composites with boosting mechanical and friction properties

Extensive attention has been drawn to the development of carbon-matrix composites for application in the aerospace and military industry, where a combination of high mechanical strength and excellent frictional properties are required. Herein, carbon-matrix composites reinforced by Si3N4 nanowires@pyrolytic carbon nanolayers (Si3N4nws@PyCnls) coupled with hydroxyapatite nanosheets is reported. The Si3N4nws@PyCnls (SP) with coaxial structure could increase the surface roughness of Si3N4nws and promote the stress transfer to the carbon matrix, whereas the porous hydroxyapatite nanosheets favor the infiltration of the carbon matrix and promote the interfacial bonding between the SP and carbon matrix. The carbon matrix composites reinforced by SP coupled with hydroxyapatite nanosheets (Si3N4nws@PyCnls-HA-C) exhibit excellent mechanical strength. Compare with the conventional Si3N4nws reinforced carbon composites, Si3N4nws@PyCnls-HA-C (SPHC) have 162% and 249% improvement in flexural strength and elastic modulus, respectively. Moreover, the friction coefficient and wear rate decreased by 53% and 23%, respectively. This study provides a co-reinforcement strategy generated by SP coupled with hydroxyapatite nanosheets for effective improvement of mechanical and frictional properties of carbon matrix composites that are used for aerospace and military industry applications.

Hollow ZnO/Fe3O4@C Nanofibers for Efficient Electromagnetic Wave Absorption

A type of hollow core–shell ZnO/Fe3O4@C fibers were fabricated by a facile combination of electrospinning, calcination, and pyrolytic pyrrole-derived carbon coating. The combination of ZnO/Fe3O4 fibers and carbon nanolayer improved the dielectric loss capability of the nanocomposites and obtained good impedance matching, leading to excellent electromagnetic wave (EMW) absorption performance. The minimum reflection loss of the ZnO/Fe3O4@C nanocomposites reached −74.2 dB at a thickness of merely 2.2 mm, and the effective absorption bandwidth reached 5.5 GHz at a matching thickness of 2.1 mm. Compared with the ZnO- or Fe3O4-based composites ever reported, our ZnO/Fe3O4@C nanocomposites exhibited superior EMW absorption characteristics due to the efficient design of multiple synergistical components and hollow fibrous structures. Combined with the facile, scalable preparation approach, the hollow core–shell ZnO/Fe3O4@C nanocomposite fibers with high EMW absorption performance show great potential for EMW absorption applications.

Carbon nanotubes coated with hybrid nanocarbon layers for electrochemical sensing of psychoactive drug

Heteroatom and transition metal borides-doped carbon nanomaterials provide a simple, yet powerful sensing platform when combined with electrochemical sensing technologies. However, there is a large unmet need for reliable and portable psychoactive drug measurement systems for environmental science or criminal investigation applications. Herein, a highly sensitive portable electrochemical sensing platform was designed for the psychoactive drug. Building on this we combine heteroatom (N) and transition metal borides (WB) in a carbon nanotube to form a high performance sensing for the detection of heroin. Moreover, this creates an electrochemical sensor for heroin that is capable of being run by the flexible screen printing electrode (SPE). Importantly, the experimental results were in excellent agreement with our proposed model, which creates hybrid nanocarbon layers of differing charge densities and abundant active sites on the surface of the carbon nanocomposites. The density and diameter of these zones also affect both the viability and sensitivity of the assay. In a proof-of-concept study, this approach allows the interrogation of the real samples from the natural water environment, and then which highlights the enlightenment and considerations for the future design of electrode materials and construction of sensors.

A Precise BSA Protein Template Developed the C, N, S Co-Doped Fe3O4 Nanolayers as Anodes for Efficient Lithium-Ion Batteries

Protein has abundant and exquisite multidimensional structures and numerous functional groups that can bind metal ions. Taking protein as a template can effectively promote the synthesis of metal oxide nanomaterials and form multidimensional network structures, which has great prospects in preparing high-performance lithium-ion battery (LIB) anode. However, these templates only act as carbon skeletons to support electrode materials. The biodiversity of proteins in precise regulation is not fully realized, limiting the application potential of protein templates. In this work, we selected biomineralized protein BSA as the template for the electrode materials synthesis, successfully regulated the nanocrystal and microstructure, and obtained a high-quality anode material with nanonetwork and ultrathin nanolayer structure. The nanocrystals of synthesized anode materials showed good uniformity and monodispersity, achieved the heteroatom doping, such as N and S elements, and in situ carbon coating. The carbon nanolayer structure formed by BSA protein improved the capacitance and stability of electrode materials, revealing a good application value for the LIB anode. This research can give us a further understanding and expand the idea of protein templates in the preparation of high-performance energy storage nanomaterials.

Confined Mesospace Synthesis of Sulfur‐Doped Graphene Quantum Dots for Direct H2O2 Detection

AbstractGraphene quantum dots (GQDs) have attracted significant interest for the design of fluorescence sensors. Hydrogen peroxide (H2O2) participates in human metabolism and is widely used in chemical and food industries. Therefore, the effective detection of H2O2 is highly desirable. Herein, an effective sensing platform is proposed for the direct detection of H2O2 using sulfur‐doped GQDs (S‐GQDs) as novel fluorescent probes. The S‐GQDs were prepared using a nanospace‐confined strategy, in which sulfur‐doped carbon nanolayers were cut into S‐GQDs using sulfuric and acetic acids in the mesoporous space of silica SBA‐15. Based on the excellent dispersibility, high photostability, and abundant oxygen/sulfur functional groups of S‐GQDs, an effective fluorescence sensor was developed for the direct detection of H2O2 without the aid of a third party. The developed sensor could be used with real samples for H2O2 detection. This paper proposes a novel method of exploiting GQDs for the direct detection of molecules.