Carbon Nanoparticle Films Research Articles

Tailoring the temperature coefficient of resistance of flame-formed carbon nanoparticle thin films by electric field-assisted deposition

The electric-field assisted deposition is successfully proposed as a method for the manufacturing of carbon nanostructured films with tunable properties, benefiting from the superimposition of electric fields on the thermophoretic deposition. Morphology, optical, and thermo-resistive properties of the carbon nanoparticle (CNP) films have been studied by UV–vis Absorption Spectroscopy, Scanning Electron Microscopy, Atomic Force Microscopy, and Current-Voltage analysis. In comparison to thermophoresis alone, the introduction of an electric field results in a six-fold increase in the deposition rate characterized by a non-linear film growth influenced by a three-fold augmentation in surface roughness and polarization effects. Notably, the surface morphology of the CNP films undergoes modification, exhibiting larger grains and a reduced optical band gap energy. Moreover, while maintaining a non-ohmic behaviour, the electric field plays a crucial role in increasing by about two orders of magnitude the electrical conductance of CNP films at ambient temperature. This effect is accompanied by a decrease in temperature sensitivity, attributed to the low and nearly temperature-independent activation energy for the tunneling of electrons in the percolative network. In summary, electric-field assisted deposition is a promising approach to tailor the thermal response of CNP films, which could be beneficial for the development of next-generation sensors.

Modelling the electrophoretically-enhanced in-flame deposition of carbon nanoparticles

Flame synthesis of Carbon NanoParticle (CNP) films is gaining strong interest for novel industrial applications because of the easy tuning of the operating conditions that enables accurate control of the chemical and physical properties of the produced CNPs. This work proposes a novelty in the synthesis of CNP films, namely the possibility of applying electric fields in flame to trigger electrophoretic deposition phenomena. In this way, it is possible to add another degree of freedom to the harvesting process and potentially modify the properties of the CNP films, without changing the operating flame conditions. To investigate the physical mechanisms governing the thermo-electrophoretic deposition of CNPs, a numerical model to simulate the particle dynamics close to the collecting substrate has been developed, and experiments have been carried out to provide highly controlled test conditions that can be used to support model validation. The experimental results consist of Atomic Force Microscopy (AFM) measurements to determine the number of particles deposited after a controlled harvesting condition as a function of the applied electrophoretic force, imposed on the substrate by means of a DC voltage varied from 0 to -3kV. The AFM shows that the amount of deposited material increases up to six times when passing from an uncharged to the -3kV charged case. The model predictions are highly consistent with the AFM measurements and pointed out that the electric field in flame significantly alters the CNP deposition velocities and impact angles, which are likely to affect the properties of the film.

Synthesis of smooth low friction graphitic nanoparticle film by vacuum arc deposition

Formation of smooth low friction carbon onion nanoparticle film was carried out using vacuum arc deposition. Carbon onions were synthesized by the arc discharge of carbon rod as a cathode and deposited directly onto the substrate in a vacuum. The process of carbon onion synthesis and nanoparticle film growth was investigated using transmission electron microscopy (TEM), atomic force microscopy (AFM), and quadrupole mass spectrometer (QMS). It was observed that isolated carbon onions were successfully synthesized by pulsed arc discharge of the carbon rod as a cathode under relatively low pressure of 10−7 Pa. The synthesized isolated carbon onions around the cathode were in flight in vacuum and deposited onto the substrate. A smooth carbon onion nanoparticle film with surface roughness (Ra) of 0.37 nm was gradually formed on a graphite substrate by 100 pulse shots of the arc discharge. A smooth nanoparticle film was achieved due to the mixture of the deposition of carbon onions and amorphous carbon in this process, where amorphous carbons were filled between carbon onions interparticle. AFM friction measurements in the vacuum revealed that the synthesized nanoparticle film possessed lower friction coefficient than graphite, which was attributed to the low adhesive force and smooth surface roughness of the carbon onion nanoparticle film.

Single‐stage plasma‐chemical synthesis and characterization of carbon nanoparticle‐polymer suspensions

AbstractA thin‐film styrene polymer–carbon nanoparticle composite was obtained in a single‐stage alternating current dielectric barrier discharge plasma‐chemical process. The allotropic forms of the carbon nanoparticle filler were traced by transmission electron microscopy (TEM). TEM revealed an extraordinary adhesive encapsulation of the carbon nanoparticles by the polymer. It was found that the corona discharge regime provides an onion‐like carbon filler that enhances the mechanical strength and chemical resistance of the synthesized polymer–carbon nanoparticle film. Measurements of the electrical properties of the films implicitly confirmed the uniformity of the carbon filler distribution.

Highly robust nanostructured carbon films by thermal reconfiguration of ionomer binding

A dramatic improvement in the mechanical robustness of fragile carbon nanoparticle films formed by a network of ionomer binders.

A Self-Powered Nanogenerator for the Electrical Protection of Integrated Circuits from Trace Amounts of Liquid

HighlightsA power generator based on carbon nanoparticles and TiO2 nanowires was fabricated by sequential electrophoretic deposition.Benefit from the special structure of the carbon nanoparticle films, the generator exhibited an fast and reliable response to liquids.A possible system for printed circuit board protection using an array of power generators was proposed.

Impurity assisted hopping conduction and persistent photoconductivity in disordered carbon nanoparticle film

We report the temperature-dependent electrical transport and photoconductivity in carbon nanoparticle films. The electrical transport is dominated by thermally activated conduction at higher temperatures in the range of ∼350–285 K, whereas at lower temperatures <280 K, the conduction is mostly due to the hopping mechanism. A film of an n-type semiconductor with a carrier concentration of ∼1016 cm−3 is prepared by pulsed laser ablation in the scanning technique. The photoconductivity shows a persistent behavior that lasts for several hundreds of seconds on sub-bandgap laser excitations. A broad green luminescence spectrum suggests the presence of a large number of oxygenated-impurity states in the nanoparticles. An unusual behavior in the temperature-dependent photoluminescence is observed in which the photoluminescence intensity first increases up to ∼100 K with the increasing temperature followed by a continuous decrease at higher temperatures. The observed persistent nature of the photocurrent and anomalous temperature dependence in photoluminescence is attributed to the presence of a large number of trap states in the nanoparticles. Due to the ability to trap and retain charges within the disordered carbon nanoparticle films, it can be utilized in the memory applications.

Application of combustion flames for generation of third harmonic and super-hydrophobic coating of glasses by deposited carbon nanoparticle films

We analyzed the third harmonic generation (THG) of 1064 nm, 28 ps radiation in the candle and ethanol flames. The formation of soot nanoparticles in the candle flame led to the increase of third harmonic yield compared to the ethanol flame. 12- and 24-fold enhancement of the third harmonic yield in candle and ethanol flames compared to the THG in air was achieved. The influence of the nonlinear refraction in air and combustion flames on the phase-matching conditions of THG was found responsible for deviation from the cubic I3ω (Iω) dependence. THG conversion efficiencies of Nd:YAG laser radiation were found to be 1 × 10−5, 1.2 × 10−4 and 2.4 × 10−4 in the cases of air, carbon flame and ethanol flame media, respectively. Furthermore, the super-hydrophobic properties of the deposited carbon species from the candle flame were demonstrated.

Surface functional modification boosts the output of an evaporation-driven water flow nanogenerator

Harvesting environmental thermal energy from a natural evaporation process is a promising method for acquiring renewable and sustainable energy. Here, we present an evaporation-driven water flow nanogenerator based on a piece of flexible carbon nanoparticle film. The open-circuit voltage of one single-piece device can be tuned from − 3 to 3 V by manipulating the surface functional groups on the carbon nanoparticles. The effects of different modification molecules and solution concentrations were also investigated. By combining the modified carbon films with opposite surface charges, we enhanced the output of the generator to a maximum open-circuit voltage of 5 V and a short-circuit current of 1.5 μA with a film size of 5 cm × 5 cm. Furthermore, the device can be easily integrated with carbon nanotube-based supercapacitors (CNT-SCs) to assemble the energy-storing and energy-harvesting devices into a self-sustaining power system. The electrical output of the device can directly power a liquid crystal display in an ambient environment and a blue LED with help of self-charged built-in SCs. This eco-friendly device, with its low cost and simple fabrication, shows great potential for future clean energy utilization and for extending the field of portable electronics.

Fabrication and photovoltaic performance of counter electrode of 3D porous carbon composite

Dye-sensitized solar cell (DSSC) has been widely investigated due to its low cost, simple fabrication process, and excellent photoelectric conversion efficiency. Generally, the DSSC is composed of photoanode, electrolyte and counter electrode. At present, platinum (Pt) film delivers the highest photoelectric conversion efficiency in the available counter electrode materials. However, Pt film is very expensive and prepared by relatively complicated and high-cost magnetron sputtering, which seriously hinders the large-scale applications in DSSC. Therefore, it is of highly academic and engineering significance to develop novel counter electrode materials with low cost and high photoelectric conversion efficiency to replace expensive Pt counter electrode. Previous research shows that carbon-based nanomaterials such as graphene and carbon nanotubes ard promising to be used as highly efficient counter electrode materials. However, the high-cost and complicated fabrication process restrict their practical applications in DSSC. To address such issues, here in this work, we present and fabricate a highly efficient and low-cost three-dimensional porous carbon composite, which is constructed by the relatively dense and conductive graphite film as bottom layer (PC layer), and the porous carbon nanoparticle film as top layer (CC layer). Our fabricated DSSC consists of commercial TiO<sub>2</sub> photoanode (m 4 mm×4 mm), and PC, CC, CC/PC composite, or Pt counter electrode with a size of m 8 mm×8 mm. The results show that under illumination (100 mW/cm<sup>2</sup>) provided by a solar simulator, the short circuit current densities (open circuit voltages) of DSSCs with PC, CC, CC/PC, and Pt counter electrodes are 11.45 mA/cm<sup>2</sup> (0.72 V), 11.88 mA/cm<sup>2</sup> (0.73 V), 12.00 mA/cm<sup>2</sup> (0.75 V), and 13.46 mA/cm<sup>2</sup> (0.74 V), respectively. The filling factors of DSSCs with PC, CC, and CC/PC are 56.09%, 59.80%, 65.28%, and 62.69%, respectively; the photoelectric conversion efficiencies of DSSCs with PC, CC, and CC/PC are 4.61%, 5.20%, 5.90%, and 6.26%, respectively. It is noted that compared with CC layer or PC layer counter electrode, the CC/PC counter electrode delivers better photovoltaic performance. Particularly, the filling factor of DSSC with CC/PC (65.28%) is even 4.10% higher than that of DSSC with commercial Pt (62.69%), and the photoelectric conversion efficiency of the CC/PC-based DSSC is as large as 5.90%, which reaches 94.2% of the Pt-based DSSC (6.26%). The excellent performance of DSSC with CC/PC counter electrode is attributed to the unique three-dimensional porous structure, which can not only facilitate the transfer of electrons and ions, but also provide abundant catalytic sites; these synergistic effects greatly enhance the photovoltaic conversion performance of CC/PC-based DSSC.

Enhanced Supercapacitor Performance Using Electropolymerization of Self-Doped Polyaniline on Carbon Film.

In this work, we electrochemically deposited self-doped polyanilines (SPANI) on the surface of carbon-nanoparticle (CNP) film, enhancing the superficial faradic reactions in supercapacitors and thus improving their performance. SPANI was electrodeposited on the CNP-film employing electropolymerization of aniline (AN) and o-aminobenzene sulfonic acid (SAN) comonomers in solution. Here, SAN acts in dual roles of a self-doped monomer while it also provides an acidic environment which is suitable for electropolymerization. The performance of SPANI−CNP-based supercapacitors significantly depends upon the mole ratio of AN/SAN. Supercapacitor performance was investigated by using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD), and electrochemical impedance spectroscopy (EIS). The optimal performance of SPANI−CNP-based supercapacitor exists at AN/SAN ratio of 1.0, having the specific capacitance of 273.3 Fg−1 at the charging current density of 0.5 Ag−1.

Thermal Evaporation of Sb2Se3 as Novel Counter Electrode for Dye‐Sensitized Solar Cells

AbstractSb2Se3 was fabricated with a facile atmospheric pressure thermal evaporation procedure as counter electrode (CE) for dye‐sensitized solar cells (DSSCs). The introduction of a carbon nanoparticle (CNP) film as substrate was proved to facilitate Sb2Se3 deposition, resulting in the formation of a Sb2Se3 layer on the surface of carbon nanoparticles (denoted as CNP‐Sb2Se3). Electrochemical characterizations demonstrate the intrinsic catalytic ability of Sb2Se3 and better electrocatalytic activity and stability of Sb2Se3 deposited on CNP film in catalyzing I3‐ reduction. Evaporation temperature was found to affect the electrocatalytic activity of CNP‐Sb2Se3 and a lower temperature of 400oC was proved to be better in our case. As a result, the best performing DSSC with CNP‐Sb2Se3 CE yields a power conversion efficiency of 6.26%, which is comparable to that based on Pt CE (6.47%).

In-situ growth of antimony sulfide in carbon nanoparticle matrix: Enhanced electrocatalytic activity as counter electrode in dye-sensitized solar cells

Considering the undesirable electrocatalytic activity toward I−/I3− redox system of prinstine antimony sulfide (Sb2S3) fabricated with the existing conditions, a mesoporous carbon nanoparticle film (CNP) is introduced here for in-situ growth of Sb2S3 to construct a Sb2S3@CNP hybrid catalyst. Based on a Sb-thiourea precursor solution, in-situ growth of Sb2S3 can be achieved via solution deposition (denoted as Sb2S3@CNP-S) as well as atmospheric pressure thermal evaporation (denoted as Sb2S3@CNP-T) in CNP matrix. Structural characterizations indicate that Sb2S3 particles have well dispersed in the pores of CNP matrix. Because of the introduction of porous and conductive CNP matrix to support Sb2S3, the hybrid catalyst exhibits lower charge transfer resistance at the catalyst/electrolyte interface and higher electrocatalytic activity. When used as counter electrode (CE) for dye-sensitized solar cells (DSSCs), devices using Sb2S3@CNP hybrid catalyst as CE produce fill factor of 67.6% and 66.3%, which is significantly higher than that using pristine Sb2S3 fabricated in our previous work (52.8%). Finally, the corresponding power conversion efficiencies reach 6.69% (Sb2S3@CNP-S) and 6.24% (Sb2S3@CNP-T), respectively, which are comparable to that using Pt CE measured under the same conditions (6.74%).

Electrodeposition of Copper Oxide Nanoparticles on Precasted Carbon Nanoparticles Film for Electrochemical Investigation of anti‐HIV Drug Nevirapine

AbstractThis work describes the development of a novel electrochemical sensor based on electrodeposition of copper oxide nanoparticles onto carbon nanoparticle (CNP) film modified electrode for the analysis of the anti‐HIV drug, nevirapine (NEV). The electrochemical experiments were performed using linear sweep and cyclic voltammetry. Atomic force microscopy was applied for surface characterization of the deposited modifier film (CuO‐CNP) on glassy carbon electrode (GCE). No oxidation peak was observed for NEV on the bare GCE, but both CNP‐GCE and CuO‐CNP‐GCE showed a distinctive anodic response towards NEV with considerable enhancement (276‐fold and 350‐fold, respectively) compared to CuO‐GCE. The mechanism of the electrocatalytic process on the modified electrode surface was investigated by cyclic and linear sweep voltammetry at various potential sweep rates and pHs of the buffer solutions. The modified electrode exhibited linear dynamic range in three concentration intervals (0.1–0.8, 1–10 and 10–100 µM) with a detection limit of 66 nM. The stability, reproducibility, and repetitive usability exhibited by the proposed modified electrode are good enough to make it a suitable sensor for the determination of NEV in real samples with complex matrices such as human blood serum.

Synthesis and characterization of carbon nanoparticle films prepared by plasma‐based ion implantation

Carbon nanoparticles (CNPs) were synthesized by the plasma‐based ion implantation method, and structural variations and the synthesis mechanism of CNPs were investigated. CNPs were grown by implanting carbon ions from methane gas into thin silver films. To obtain pure CNPs from the silver matrix, the silver films were evaporated by a thermal process under high vacuum. XPS depth analysis revealed that initially silver atoms were preferably sputtered during implantation, then CNPs gradually started to appear on the silver and carbon atoms concentrated near the surface. Stacked carbons on the surface may prevent silver films from being sputtered and carbon ions from penetrating into the silver matrix. The CNPs grew up to 20 nm, but their size did not increase after the implantation for 2 h. Instead, a membrane cluster among the CNPs was observed after the implantation for 3 h. Thermal process at 750 °C for removing silver to obtain only CNPs did not affect CNP growth. Raman spectra indicated that spherical CNPs consist of graphitic structure and long‐time implantation yielded amorphous membranes as well as the CNPs. Copyright © 2014 John Wiley & Sons, Ltd.

Investigations on high enthalpy shock wave exposed graphitic carbon nanoparticles

The impact of high enthalpy shock wave on graphitic carbon nanoparticle (GCNP) films has been investigated and discussed in view of space and chemical engineering applications. The GCNP films were developed by using spray method and exposed to high enthalpy shock wave under an inert atmosphere. Upon shock wave treatment, two typical amendments such as weight loss in the deposited material and growth of second order nanostructures (SONs) have been observed. While increasing test gas pressure, the loss of material and density of SONs are gradually increased. Most of the shock wave induced SONs are highly crystalline and belong to the cubic diamond structure. Upon shock treatment as well as with increase of test gas pressure, a considerable improvement in the quality of GCNP films has been observed. Further, ablation of GCNPs exclusively on the top surface of the coatings and formation of hierarchical NPs (diamond NPs on GCNPs) has been observed.

6PM1-C-4 プラズマ利用イオン注入法を用いたカーボンナノ粒子膜の合成およびその摩擦・摩耗特性(6PM1-C OS6 マイクロナノトライボロジー(2))

6PM1-C-4 プラズマ利用イオン注入法を用いたカーボンナノ粒子膜の合成およびその摩擦・摩耗特性(6PM1-C OS6 マイクロナノトライボロジー(2))

Hydrothermal core–shell carbon nanoparticle films: thinning the shell leads to dramatic pH response

Carbon nanoparticles with phenylsulfonate negative surface functionality (Emperor 2000, Cabot Corp.) are coated with positive chitosan followed by hydrothermal carbonization to give highly pH-responsive core-shell nanocarbon composite materials. With optimised core-shell ratio (resulting in an average shell thickness of ca. 4 nm, estimated from SANS data) modified electrodes exhibit highly pH-sensitive resistance, capacitance, and Faradaic electron transfer responses (solution based, covalently bound, or hydrothermally embedded). A shell "double layer exclusion" mechanism is discussed to explain the observed pH switching effects. Based on this mechanism, a broader range of future applications of responsive core-shell nanoparticles are envisaged.

Comparison of dye solar cell counter electrodes based on different carbon nanostructures

Three characteristically different carbon nanomaterials were compared and analyzed as platinum-free counter electrodes for dye solar cells: 1) single-walled carbon nanotube (SWCNT) random network films on glass, 2) aligned multi-walled carbon nanotube (MWCNT) forest films on Inconel steel and quartz, and 3) pressed carbon nanoparticle composite films on indium tin oxide-polyethylene terephtalate plastic. Results from electrochemical impedance spectroscopy and electron microscopy were discussed in terms of the catalytic activity, conductivity, thickness, transparency and flexibility of the electrode films. The SWCNT films showed reasonable catalytic performance at similar series resistance compared to platinized fluorine doped tin oxide-coated glass. The MWCNTs had similar catalytic activity, but the electrochemical performance of the films was limited by their high porosity. Carbon nanoparticle films had the lowest charge transfer resistance resulting from a combination of high catalytic activity and dense packing of the material.

Made-to-order nanocarbons through deterministic plasma nanotechnology

Through a combinatorial approach involving experimental measurement and plasma modelling, it is shown that a high degree of control over diamond-like nanocarbon film sp3/sp2 ratio (and hence film properties) may be exercised, starting at the level of electrons (through modification of the plasma electron energy distribution function). Hydrogenated amorphous carbon nanoparticle films with high percentages of diamond-like bonds are grown using a middle-frequency (2 MHz) inductively coupled Ar+CH4 plasma. The sp3 fractions measured by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy in the thin films are explained qualitatively using sp3/sp2 ratios 1) derived from calculated sp3 and sp2 hybridized precursor species densities in a global plasma discharge model and 2) measured experimentally. It is shown that at high discharge power and lower CH4 concentrations, the sp3/sp2 fraction is higher. Our results suggest that a combination of predictive modeling and experimental studies is instrumental to achieve deterministically grown made-to-order diamond-like nanocarbons suitable for a variety of applications spanning from nano-magnetic resonance imaging to spin-flip quantum information devices. This deterministic approach can be extended to graphene, carbon nanotips, nanodiamond and other nanocarbon materials for a variety of applications.