Growth Of Carbon Nanostructures Research Articles

Controlling carbon nanostructure synthesis in thermal plasma jet: Correlation of process parameters, plasma characteristics, and product morphology

Thermal plasma has emerged as an effective approach for producing carbon nanostructures without the need for specific catalysts nor substrates. While efforts have focused on the effect of process parameters such as reaction pressure, input power or carbon source, the intricate role and relationship with plasma characteristics like density and temperature are often overlooked due to the complexity of the environment. This study addresses this gap by establishing a correlation between process parameters, plasma characteristics, and product morphology, essential for controlling the growth of carbon nanostructures. We explored the impact of carbon precursor type (CH4 and C2H2), hydrogen, pressure, and flow rate on nanostructure formation. Using in situ optical emission spectroscopy (OES), we mapped the distribution of both temperature and dicarbon molecule (C2) density within the plasma jet. We demonstrate that the growth of low-density nanostructures, such as carbon nanohorns (CNHs), is favoured at dilute C2 local densities and high temperatures, while denser nanostructures, such as onion-like polyhedral graphitic nanocapsules (GNCs), are favoured at higher C2 densities and lower temperatures. The carbon density can be controlled by the flow rate and the pressure, which in turn significantly influence the nanostructure morphology, evolving from graphene nanoflakes (GNFs) to GNCs as either parameter increases. Increasing the H/C ratio from 1 to 8 resulted in a morphological transition from CNHs to GNFs. During the synthesis, the plasma jet temperature surpassed 3000 K, with crystalline growth occurring 50–100 mm below the nozzle.

Investigation of Ni/Ni3C Nanoparticle Synthesis for Application as a Catalyst in Carbon Nanostructure Growth

Investigation of Ni/Ni₃C Nanoparticle Synthesis for Application as a Catalyst in Carbon Nanostructure Growth

Modeling and characterization of the nucleation and growth of carbon nanostructures in physical synthesis

Carbon nanostructures formed through physical synthesis come in a variety of sizes and shapes. With the end goal of rationalizing synthetic pathways of carbon nanostructures as a function of tunable parameters in the synthesis, we investigate how the initial density and quench rate influence the morphology of carbon nanostructures obtained from the cooling of a gas of atomic carbon by molecular dynamics simulations. For the structural analysis, we combine classical order parameters with a data-driven approach based on local density descriptors and kernel similarity measurements. Aided by this complementary set of tools, we describe in detail the formation of carbon nanostructures from the gas phase. Their formation proceeds through the nucleation of small liquid carbon nanoclusters followed by growth into unique objects. We find that ordered structures can only be obtained at certain quenching rates and that among those, fullerene-like particles are favored at intermediate densities while nanotubes-like structures require higher initial densities. © XXXX CEA. Elsevier

Low temperature direct growth of carbon nanostructures on basalt fibers

Among natural fibers, basalt fibers have recently emerged as the main candidate to replace glass fibers in composite materials. Since the fiber/matrix interface strongly influences the final mechanical properties in a fiber reinforced composite, the current aim is to optimize the efficiency of the load transfer between the two different phases in the composite by growing carbon nanostructures (CNS), both nanofibers and nanotubes, on the surface of unsized basalt fibers exploiting less common catalysts compared to transition metals. Carbon nanostructures were grown onto unsized basalt fibers by chemical vapor deposition under different growth temperatures, using three different catalysts: copper, sodium, and iron. Considering the negative influence that high temperature has on the mechanical properties of basalt fibers, by lowering the synthesis temperature, we preserved the intrinsic properties of the basalt fibers, losing only 5% of the tensile strength at 300 °C growth temperature with a copper-based catalyst, while obtaining dense and uniform CNS growth. The different morphologies of the CNS obtained on the surface of the fibers were investigated by morphological and spectroscopic analyzes, while fiber/matrix adhesion was characterized by single fiber pull out tests, showing increases of 30% and 60% in interfacial shear strength and total pull out work, respectively. These less common catalysts provide an expanded design strategy for obtaining composites with improved interfacial bonding and multifunctional properties.

Aerogels containing ionomers and microwave assisted growth of carbon nanostructures on carbon urchins for multifunctional electromagnetic interference shielding

Hierarchal 3D porous carbon materials show huge potential for EMI shielding because of their adjustable pore structure, tunable morphology and high electrical conductivity. However, poor graphitic nature and improper contact between materials lead to reduce the inherent conductivity, which supress the EMI shielding performance. In this work, we designed a hierarchical Carbon–Carbon nanostructure, which resembles a ‘sea-urchin’, exhibiting high shielding performance. A facile strategy of microwave assisted growth of carbon nanofiber (CNF) on the ‘self-assembled’ carbon urchin (CU) holds the rank of hierarchy, which enhance the electrical contact between the urchins. In order to obtain a 3D construct, a classical Ionomers pair-PEDOT:PSS was chosen as the matrix and CNF@CU was infused and subjected to freeze-drying to design ultra-light aerogel. The morphological assessment reveals that CNF@CU in the aerogel offers trapping centers by providing multiple interfaces. The aerogels exhibited two orders of jump in electrical conductivity and showed excellent thermal stability. The high limiting oxygen index value begins to suggest that these aerogels can extend their utility to flame retardant materials. The EMI shielding properties of the construct were studied in the X-band (8.2–12.4 GHz). The aerogel with 1.7 wt% of CNF@CU exhibited −50.8 dB of shielding efficiency (representing 99.999% blocking). The excellent EMI performance achieved here is mainly due to the conductive losses, dipole polarization, interface polarization, and wave trappers. These wave trappers are extremely beneficial for shielding EM radiations through multiple scattering. The utility of these materials were further evaluated using a Bluetooth module, wherein the aerogel potentially blocked all the transmitting Bluetooth signals confirming the quick shielding quality of the proposed aerogel. Taken together, this work provides a facile approach for designing and developing lightweight aerogel based EMI shielding materials.

Interface Interaction Dependent Growth of Carbon Nanostructures: An In Situ Study (Adv. Mater. Interfaces 19/2022)

Controllable Growth of Carbon Nanostructures In article number 2200334, Xiaofang Zhang, Rongming Wang, and co-workers demonstrate controllable growth of graphite shells (GSs) and bamboo carbon nanotubes (CNTs) by adjusting the interface interaction between catalyst and substrate via temperature, i.e., high temperature favores tip-growth of bamboo CNTs with larger catalyst nanoparticles, and low temperature favores base-growth of GSs with smaller nanoparticles, which is revealed via in-situ pyrolysis of Co phthalocyanine in an aberration-corrected ETEM.

Facile Synthesis of Catalyst Free Carbon Nanoparticles From the Soot of Natural Oils

The growth of carbon nanostructures from vegetable oils using a modified conventional approach is a simple and environmentally friendly technology with controllable features. The goal of this study is to develop a simple and environmentally friendly process for making carbon nanoparticles using commercially available, low-cost vegetable oils. The technique involves the controlled burning of “Mustard”, “Olive”, and “Linseed” oils using the traditional clay lamps and collecting the carbon soot on a ceramic plate. The prepared carbon nanoparticles were purified through sonication and subjected to characterization using powder X-ray diffraction, SEM, Fourier transformed infrared, Thermogravimetric and differential scanning calorimetric analyses. The average particle size of carbon nanoparticles as investigated by powder X-Ray Diffraction analyses was found to be 18, 24, and 57 nm for mustard, olive and linseed oils respectively. SEM analyses revealed the surface morphology of these carbon nanostructures as spherical particles. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) providing knowledge about the thermal stability of these carbon nanoparticles. The synthesized carbon nanoparticles were screened for antibacterial activities against different species (e.g., Pseudomonas aeruginosa, Streptococcus haemolyticus, Proteus refrigere and Staphylococcus aureus) and fruitful results have been obtained.

Interface Interaction Dependent Growth of Carbon Nanostructures: An In Situ Study

AbstractControllable synthesis of carbon nanostructures is expected to achieve high electrical, optical, and mechanical performance for various applications. Despite great progress in this field, controllable synthesis of carbon nanostructures, i.e., graphite shells (GSs) and carbon nanotubes (CNTs), is still demanded to be deeply revealed. Here, a strategy is demonstrated to achieve GSs and bamboo CNTs by regulating the interface interaction via in situ pyrolysis of Co phthalocyanine (CoPc) in an environmental transmission electron microscopy (ETEM) at atomic resolution. The results indicate that the catalyst involves the nucleation, combination, and reconstruction of Co/Co3C, the growth modes of the carbon, i.e., base‐growth or tip‐growth, and nanostructures are dependent on the interface interaction between catalyst and substrate controlled by temperature. High temperature favors tip‐growth of bamboo CNTs with larger catalyst nanoparticles (NPs) (≈20 nm), while low temperature favors the base‐growth of GSs with smaller NPs (≈10 nm). The average growth rate of 131.3 nm s−1 at 850 °C is about 60 times compared with that at 750 °C. The work provides a comprehensive understanding of distinct growth mode of GSs and CNTs at different temperatures, which would be valuable for the controllable growth of carbon nanostructures by catalyst design and engineering.

Modeling and Characterization of the Nucleation and Growth of Carbon Nanostructures in Physical Synthesis

Modeling and Characterization of the Nucleation and Growth of Carbon Nanostructures in Physical Synthesis

Numerical modelling of non-premixed biogas and LPG combustion to study carbon nanostructures formation in flame

This work presents the numerical simulation of biogas and LPG fuelled diffusion flames in an axisymmetric chamber to study in-depth, the formation mechanism of soot and carbon nanostructures in these flames. The simulation is formulated on the set of transport equations that involve the equations for conservation of mass (the continuity equation), momentum (Navier-Stokes equation), energy, and chemical species. The governing equations are solved using ANSYS FLUENT, which is centered on the finite volume method. To predict the soot formation, one step soot model has been incorporated. The solution of these equations permits the estimation of temperature field and species concentrations inside the flame. Simulation is conducted at fixed fuel flow rate and varied oxygen flow rates. The results reveal that the formation of soot and carbon nanostructures is strongly dependent on peak flame temperature and concentration of precursor species formed in the flame. Since two fuels produce an exclusive chemical environment in the flame, the flame temperature and CO concentration that is conducive to the growth of carbon nanostructures is higher for LPG fuel as compared to that for biogas. Hence, the nucleation process of carbon nanostructures is faster for LPG than biogas. Moreover, the reactions taking place inside the flame at different locations can also be predicted from flame temperature and species concentration at that location. Pyrolysis of fuel occur near the burner exit, followed by the nucleation and surface growth of carbon nanostructures in the nearby region and oxidation of formed carbon nanostructures near the flame tip.

Carbon nanostructure growth: new application of magnetron discharge

Purpose: The application of a common magnetron discharge to the growth of carbon nanostructures is studied. The simplicity of the proposed technique can be beneficial for the development of new plasma reactors for large-scale production of carbon nanostructures. Design/methodology/approach: Graphite cathode was treated by carbon-containing powder accelerated by use of nozzle, and then aged in hydrogen. Superposition of glow and arc discharges was obtained, when putting the cathode under the negative biasing with respect to the walls of a vacuum chamber. The pulsed discharge was preserved through the whole time of treatment. This process was explained in terms of interaction of glow discharge plasma with a surface of the cathode made of non-melting material. Findings: The plasma treatment resulted in generation of the diverse nanostructures confirmed by SEM and TEM images. Spruce-like nanostructures and nanofibers are observed near the cathode edge where the plasma was less dense; a grass-like structure was grown in the area of “race-track”; net-like nanostructures are found among the nanofibers. These findings allow concluding about the possible implementation of the proposed method in industry. Research limitations/implications: The main limitation is conditioned by an explosive nature of nanostructure generation in arcs; thus, more elaborate design of the setup should be developed in order to collect the nanospecies in the following study. Practical implications: High-productivity plasma process of nanosynthesis was confirmed in this research. It can be used for possible manufacturing of field emitters, gas sensors, and supercapacitors. Originality/value: Synthesis of carbon nanostructures is conducted by use of a simple and well-known technique of magnetron sputtering deposition where a preliminary surface treatment is added to expand the production yield and diversity of the obtained nanostructures.

Electrochemical Capture and Conversion of Carbon Dioxide into All-Carbon Nanostructures

To address the rising levels of atmospheric carbon, recent efforts have considered the capture of CO2 from release points, such as power plants, and conversion into chemicals including formic acid, methanol, CO, and ethylene. In this technique, CO2 acts as the chemical feedstock for the manufacturing of useful chemicals and provides the potential for a viable secondary market for otherwise pollutant gases, which are normally expensive to sequester. However, these routes for CO2 conversion are bottlenecked by the cost of operation versus the perceived economic benefit to society, and these low-value materials produced at low efficiencies, often from expensive catalyst materials, undermine the rationale of this approach. These issues can be resolved with the development of techniques that capture and convert atmospheric CO2 into more valuable materials that can be developed into high-value products.In contrast to the hydrogenation of CO2 into hydrocarbons and alcohols, liquid-phase electrochemical splitting of CO2 into its individual elemental constituents has been investigated beginning with aqueous electrolytes. However, low solubility of CO2 in aqueous solution and similar reaction potentials for water splitting were problematic. CO2 splitting in room temperature ionic liquids (RTILs) has been studied for their attractive electrochemical window and high solubility of CO2, but the high cost and toxicity of RTILs makes their commercial adoption impractical. In contrast to these methods, molten carbonates boast low cost and high ionic conductivity with a low vapor pressure, and have been proven as viable electrolytes for the capture and electrochemical splitting of CO2 dating back now seven decades. This method relies on the decomposition of dissolved CO2 between two biased electrodes, where elemental carbon is captured at the cathode, and the resulting structures of the deposited carbons are largely dependent on process parameters including electrolyte, current density, and electrode materials.The last 25 years have been lauded as perhaps the most exciting for carbon researchers due to the emergence of nanostructured carbon materials with extraordinary mechanical, thermal, and electronic properties that cannot be replicated in other known materials. The most mature family of carbon nanomaterials in the literature and industrial applications is carbon nanotubes, which are typically grown in a gas-phase chemical vapor deposition method. In contrast to this mature field, the growth of carbon nanostructures from the liquid-phase electrochemical reduction of CO2 remains only a new field of research, with the most recent work demonstrating growth of large-diameter (>100 nm) CNTs and few-layer graphene flakes from CO2 conversion. These initial works demonstrate the capability to leverage CO2 as a precursor in carbon nanostructure growth, even though forward-looking efforts to achieve high quality, precisely tuned materials such as small diameter CNTs or single-layered graphene at high yields will require control of the process beyond the systems-level approaches reported so far. This presents an exciting frontier that exists at the intersection of these two communities – those who have studied the mechanistic details of catalytic processes relating to nucleation and growth of nanostructures, and those who are focused on systems-level directions to develop platforms which can address important global issues.SkyNano has developed technologies to capture and convert CO2 into all-carbon nanostructures such as small diameter CNTs mediated by molten salt electrolysis. This talk will focus on our work thus far, including the engineering of inert anodes with thin film deposition of materials to activate catalytic activity at the cathode as the basis for CNT growth, the utilization of pre-deposited catalyst onto cathode architectures and mechanistic understand of dynamic catalyst processes that take place over time, such as Ostwald ripening. We will also discuss our efforts to utilize flue-gas sourced CO2 in collaboration with the Tennessee Valley Authority, in an effort to transition from the laboratory to industrial scale. Finally, this talk will address challenges we see for the field of CO2-to-carbon conversion, and the pathways we believe exist for those interested in scaling from the laboratory to the marketplace. Figure 1

Formation of metal catalytic centers from atomic flows of matter for the growth of carbon nanostructures using PECVD method

Consider formation of nickel catalytic centers from atomic flows obtained by the method of vacuum resistive evaporation. A model of formation kinetics of catalytic centers of nickel from atomic flows has been constructed. A complete model of theoretical studies of the formation of catalytic centers of nickel on a silicon surface is shown. A dependence of cluster concentration on normalized formation time is obtained. According to the results of theoretical studies, it was learned that flux of nickel atoms to substrate is F = 1.296 * 1018, residence time of nickel atom on substrate in adsorbed state is tg = 5.135 * 10−7, and concentration of adsorbed atoms as a function of time is N = 6.657 * 1011.

Mechanisms of selective nanocarbon synthesis inside carbon nanotubes

The possibility of confinement effects inside a carbon nanotube provides new application opportunities, e.g., growth of novel carbon nanostructures. However, the understanding the precise role of catalyst-feedstock in the nanostructure synthesis is still elusive. In our simulation-based study, we investigate the Ni-catalyzed growth mechanism of encapsulated carbon nanostructures, viz. double-wall carbon nanotube and graphene nanoribbon, from carbon and hydrocarbon growth precursors, respectively. Specifically, we find that the tube and ribbon growth is determined by a catalyst-vs-feedstock competition effect. We compare our results, i.e., growth mechanism and structure morphology with all available theoretical and experimental data. Our calculations show that all encapsulated nanostructures contain metal (catalyst) atoms and such structures are less stable than their pure counterparts. Therefore, we study the purification mechanism of these structures. In general, this study opens a possible route to the controllable synthesis of tubular and planar carbon nanostructures for today’s nanotechnology.

Oriented Carbon Nanostructures from Plasma Reformed Resorcinol-Formaldehyde Polymer Gels for Gas Sensor Applications.

Oriented carbon nanostructures (OCNs) with dominant graphitic characteristics have attracted research interest for various applications due to the excellent electrical and optical properties owing to their vertical orientation, interconnected structures, electronic properties, and large surface area. Plasma enhanced chemical vapor deposition (PECVD) is considered as a promising method for the large-scale synthesis of OCNs. Alternatively, structural reformation of natural carbon precursor or phenol-based polymers using plasma-assisted surface treatment is also considered for the fabrication of OCNs. In this work, we have demonstrated a fast technique for the synthesis of OCNs by plasma-assisted structure reformation of resorcinol-formaldehyde (RF) polymer gels using radio-frequency inductively coupled plasma (rf-ICP). A thin layer of RF polymer gel cast on a glass substrate was used as the carbon source and treated with rf plasma under different plasma discharge conditions. Argon and hydrogen gases were used in surface treatment, and the growth of carbon nanostructures at different discharge parameters was systematically examined. This study explored the influence of the gas flow rate, the plasma power, and the treatment time on the structural reformation of polymer gel to produce OCNs. Moreover, the gas-sensing properties of as-prepared OCNs towards ethanol at atmospheric conditions were also investigated.

Catalytic growth of CNTs and carbon onions by chemical vapor deposition on nickel-silica nanocomposite and its electrochemical catalytic study towards OER

Novel carbon nanostructures are desired to develop alternative to noble metals like Iridium or Ruthenium based electrocatalysts as an anode material in alkaline water electrolyser. In this work first nickel-silica nanocomposite with a particles size of about 20 nm has been formed by alcogel electrolysis and then employed for catalytic growth of carbon nanostructures by CVD at 650–750 °C using alcohol precursor diluted by argon followed by electrocatalytic study towards oxygen evolution reaction (OER) in 1 M KOH solution. The carbon nanotubes of two different diameters, i.e. 10–30 nm and about 100–300 nm are seen at synthesis temperature of 650 °C. The larger tubes are replaced by irregular structures and carbon onions at 750 °C, with almost negligible nanotubes at the latter temperature. The diameter distribution of onion like carbon is found to be in the range 50–700 nm. Shift from thicker nanotubes to onions may be partly attributable to higher diffusion rates of carbon that result in complete coverage of larger nanoparticles without allowing an open end to continue the growth of a nanotubes. The small radius of curvature and extra-ordinary distortion required for carbon onions has not allowed them to grow on small nanoparticles. Moreover, our synthesized CNTs exhibited overpotentials of 354 mV at current density of 10 mA/cm2 which was 24 mV lower than revealed for carbon onions under similar conditions.

Catalytic Synthesis and Study of Carbon–Graphene Structures

The optimum conditions of production, structure, and features of the formation of carbon–graphene composites on nickel–graphene catalysts are determined. A mechanism is proposed for the formation of nickel–carbon–graphene composites that consists of several stages: reduction of graphite oxide and nickel ions; the formation and growth of Ni clusters on reduced graphite oxide; catalytic pyrolysis of ethylene on Ni single crystals attached to a graphene-like support; and the formation and growth of carbon nanostructures on the surface of graphene-like material.

Catalytic Growth of MWCNTs & Carbon Onions By Chemical Vapor Deposition on Nickel-Silica Nanocomposite Prepared Via Alcogel Electrolysis and Electrochemical Catalytic Study Towards OER

Novel carbon nanostructures are desired for development of alternative to noble metal based electrocatalyst for sustainable energy technologies like production of hydrogen. In this work first nickel-silica nanocomposite with a particles size of about 20 nm has been formed by alcogel electrolysis and employed for catalytic growth of carbon nanostructures by CVD at 650-750°C using alcohol precursor diluted by argon followed by electrocatalytic study towards oxygen evolution reaction (OER) in 1M KOH solution has been carried. The carbon nanotubes of two different diameters, i.e. 10-30 nm and about 100-300 nm are seen at synthesis temperature of 650°C. The larger tubes are replaced by irregular structures and carbon onions at 750°C, with almost negligible nanotubes at the latter temperature. The diameter distribution of onion like carbon is found to be in the range 50-700nm. Shift from thicker nanotubes to onions may be partly attributable to higher diffusion rates of carbon that result in complete coverage of larger nanoparticles without allowing an open end to continue the growth of a nanotubes. Small radius of curvature and extra-ordinary distortion required for carbon onions has not allowed them to grow on small nanoparticles.Key words: Nickel-silica Nanocomposite, Carbon Nanotubes (CNTs), Carbon onions, Chemical Vapor Deposition (CVD), OER

Hydrogen production by catalytic decomposition of methane over Fe based bi-metallic catalysts supported on CeO2–ZrO2

Methane decomposition to produce hydrogen was studied over iron based bimetallic catalysts supported on cerium-zirconium oxide in a continuous flow fixed bed reactor at 700 °C. 15 wt% Fe/CeZrO2 was prepared by wetness impregnation and the promoted Fe catalysts (15 Fe-5 Co/CeZrO2 and 15 Fe-5 Mo/CeZrO2) were prepared by co-impregnation technique. Mo promoted Fe catalyst exhibited the maximum surface area of 24.08 m2/g. X-ray diffraction studies revealed that Fe2O3, Co3O4 and MoO3 were the phases present in freshly calcined catalysts, while the reduced catalysts consisted of phases including elemental Fe, Mo and Fe–Co alloys. Both X-ray diffraction and temperature programmed reduction studies confirmed the complete reduction of metal oxide species under H2 at 700 °C. The catalytic activity of Fe/CeZrO2 was enhanced upon addition of Co and Mo as promoters. The initial hydrogen yield on 15 Fe-5 Mo/CeZrO2 was ~90% and it decreased with increase in time on stream (TOS), and finally stabilized around ~50% after 125 min of TOS. The Co promoted catalyst exhibited similar activity while the initial hydrogen yield on 15 Fe/CeZrO2 was ~83% and dropped to ~33% after 125 min of TOS. Graphitic carbon, Fe3C and Mo2C phases were observed in the XRD patterns of spent catalysts along with elemental Fe and Fe–Co alloy. It was evident from temperature programmed oxidation results that coke formation which deactivates the catalyst was dominant in 15 Fe/CeZrO2 when compared to the promoted (Co and Mo) Fe catalysts where carbon nanostructures were dominant. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the formation of carbon nanostructures on the surface of spent catalysts. The Fe based catalysts supported both tip and base-growth mechanisms for the growth of carbon nanostructures.

Study on the synthesis and properties of hierarchically structured electrospun/vapour-grown carbon nanofibres nanocomposites

Herein, we present an extensive analysis of the effect of the initial concentration of iron acetylacetonate(III) (Fe(Acac)3), serving as the catalyst for the growth of carbon nanostructures from the gas phase, on the properties and processes occurring during the synthesis of hierarchically structured electrospun/vapour-grown carbon nanofibres nanocomposites. The examined materials contained from 0 to 4.5% of Fe(Acac)3 and were analysed at various stages of the synthesis. The conducted study revealed empirical formulas correlating the Fe(Acac)3 content with the viscosity of the precursor solutions and the resulting diameters of electrospun carbon nanofibres (eCNF). The concentration of the catalyst exerted a strong impact on the morphology and density of nanoprotrusions on the surface of eCNF. The presence of the grown nanostructures caused an increase in the degree of structural ordering of the nanocomposites. Obtained results suggest also the catalytic effect of Fe(Acac)3 on the cyclisation/oxidation of polyacrylonitrile and proved the hypothesis that the presence of this compound significantly affects the course of the thermal conversion of polyacrylonitrile into the carbon. Evaluation of the wettability revealed the superhydrophobic-superoleophilic character of the nanocomposites and showed that contact angles can be easily controlled by the appropriate selection of initial concentration of Fe(Acac)3.