Morphology Of Nanomaterials Research Articles

Surface Enhanced Raman Scattering (SERS) Effects of 4-Aminothiophenol on Au Nanoparticles with Different Shapes.

Au nanoparticles with different shapes (nanosphere, nanoplate and nanorod) have been synthesized and were characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction and UV-vis absorption spectroscopy. We investigated the catalytic activity of Au nanoparticles with different morphologies as surface-enhanced Raman scattering substrates for the conversion of p-aminothiophenol to p,p'-dimercaptoazobenzene. The experimental results indicated that the order of catalytic activity is nanorod> nanoplate> nanosphere under 633 and 785 nm excitation. The current research provides some reliable insights and important references for exploration new catalysts and their catalytic activities from the perspectives of different sizes, morphology and crystal composition of nanomaterials.

Surface-enhanced Raman spectroscopy for chemical and biological sensing using nanoplasmonics: The relevance of interparticle spacing and surface morphology

In this review, the weightiest decadal developments of surface-enhanced Raman scattering (SERS) and nanoplasmonic materials in sensing applications are discussed. Today, there are several well-established research directions where plasmonic detection is employed extensively, namely, food and water quality monitoring, viruses, pathogenic bacteria and hazardous toxin investigations for theranostic applications, and explosive substance detection for military and civil protection purposes. A combination of vibrational spectroscopy and surface nanoengineering has gained a reputation as a powerful weapon for rapid and accurate determination of submolecular quantities of nanoanalytes. Signal enhancement achieved by employing various metallic nanoparticles and nanostructures can be amplified significantly due to the electromagnetic field confinement effect. Localized surface plasmon waves, which are responsible for the phenomenon, promote light absorption at nanovolume, generating ‘hot spots’ with an incredibly intense and confined electromagnetic field close to the nanosculptured metallic surface. However, the formation of the hot spot network is heavily dependent on morphology, size, and spatial arrangement of plasmonic nanomaterials. Under optimal excitation conditions, the interaction between the optically induced electromagnetic field in the hot spot region and a probing analyte attached to the nanosculptured metallic substrate enlarges photon scattering cross section, increasing signal intensity by 106–1010. As a result, fast single-molecule vibrational fingerprint recording is possible. This focused review collects recent state-of-the-art developments in nanoplasmonic SERS sensing, highlighting the most efficient surface morphology designs that hold the most promise for future developments.

Carbon Nanosheets Synthesis in a Gliding Arc Reactor: On the Reaction Routes and Process Parameters

Non-thermal plasma is a promising technology for high purity nanomaterial synthesis in a fast, flexible and controllable process. Gliding arc discharge, as one of the most efficient non-thermal plasmas, has been widely used in gas treatment but rarely studied for the nanomaterial synthesis. In this study, a comparison study for carbon nanosheets synthesis including toluene dissociation and graphite exfoliation was investigated in a 2D gliding arc reactor at atmospheric pressure. The effects of gas flow rate, precursor concentration and power input on the structures of carbon nanosheets produced through the two synthesis routes were explored and compared. Amorphous carbon nanosheets were produced in both approaches with a few crystalline structures formation in the case of toluene dissociation. The thickness of carbon nanosheets synthesized from graphite exfoliation was less than 3 nm, which was thinner and more uniform than that from toluene dissociation. The flow rate of carrier gas has direct influence on the morphology of carbon nanomaterials in the case of toluene dissociation. Carbon spheres were also produced along with nanosheets when the flow rate decreased from 2 to 0.5 L/min. However, in the case of graphite exfoliation, only carbon nanosheets were observed regardless of the change in flow rate of the carrier gas. The generated chemical species and plasma gas temperatures were measured and estimated for the mechanism study, respectively.

In-situ growth of core-shell NiCo2O4@Ni-Co layered double hydroxides for all-solid-state flexible hybrid supercapacitor

In recent years, the core-shell heterostructure has been considered as one of the most promising candidates for the next generation of electrode materials, which can not only shorten the ion diffusion distance, but also increase the contact area between the electrode and the electrolyte. Herein, two different morphologies of NiCo2O4 nanomaterials were prepared by hydrothermal-calcination method, and then the hybrid structure consisting of needle-like NiCo2O4 core and Ni-Co layered double hydroxide (Ni-Co LDH) shell is composited on carbon fiber cloth (CFC) by constant current electrodeposition as electrode materials. The resultant NiCo2O4@Ni-Co LDH core-shell hybrid arrays exhibits the specific capacitance of 4901.8 m F cm−2 at the current density of 2 mA cm−2, which is much higher than that of needle NiCo2O4 and flake Ni-Co LDH. At the same time, the obtained NiCo2O4@Ni-Co LDH as the positive electrode while the activated (AC) serves as the negative electrode, which is used to assemble the all-solid flexible asymmetric supercapacitor. It delivers an energy density of 0.859 mW h cm-3 at the power density of 2 mA cm−2, as well as an excellent cycling performance with capacitance retention of 92.3 % after 5000 cycles at 16 mA cm−2. These results suggest that this core-shell structured material could be a promising electrode for supercapacitors.

Morphologically controlled cobalt oxide nanoparticles for efficient oxygen evolution reaction

Electrochemical water oxidation is one of the thrust areas of research today in solving energy and environmental issues. The morphological control in the synthesis of nanomaterials plays a crucial role in designing efficient electrocatalyst. In general, various synthetic parameters can direct the morphology of nanomaterials and often this is the main driving force for the electrocatalyst in tuning the rate of the oxygen evolution reaction (OER) for the electrochemical water-splitting. Here, a facile and cost-effective synthesis of spinel cobalt oxides (Co3O4) via a one-pot hydrothermal pathway with tunable morphology has been demonstrated. Different kinds of morphologies have been obtained by systematically varying the reaction time i.e. nanospheres, hexagon and nanocubes. Their catalytic activity has been explored towards OER in 1.0 M alkaline KOH solution. The catalyst Co3O4-24 h nanoparticles synthesized in 24 h reaction time shows the lowest overpotential (η) value of 296 mV at 10 mA cm−2 current density, in comparison to that of other as-prepared catalysts i.e. Co3O4-pH9 (311 mV), Co3O4-12 h (337 mV), and Co3O4-6 h (342 mV) with reference to commercially available IrO2 (415 mV). Moreover, Co3O4-24 h sample shows the outstanding electrochemical stability up to 25 h time.

Controlled Synthesis of Hydroxyapatite Nanomaterials Regulated by Different Phosphorus Sources

The morphology, nanostructures, and crystallinity of hydroxyapatite (HA) materials have significant effects on their physicochemical properties and biomedical applications. However, the controllable synthesis of HA nanomaterials with various size and morphology using the same synthesis system, though desirable, has remained a challenge. In this work, we successfully synthesized HA nanomaterials with different morphologies via a one-step solvothermal route in the same reaction system. By using (NaPO3)3, Na3PO4·12H2O and NaH2PO4·2H2O as phosphorus sources, the growth of HA crystals was regulated, resulting in the transformation of HA nanomaterials morphology from nanorods to nanowires. Different concentrations of PO43− and OH− ions in the reaction environments regulated by different phosphates lead to different nanostructures of HA crystals. Our work provides an instructive way to controllably fabricate HA nanomaterials with various morphologies and will widen the biomedical applications of HA materials.

Preparation and Photocatalytic Water Splitting Hydrogen Production of Titanium Dioxide Nanosheets

Improving the efficiency of photocatalytic water splitting to produce hydrogen is currently a hot topic in research. TiO2 nanosheets are a good carrier of photocatalytic materials and have become attractive materials in the new century because of their high active surface exposure characteristics and special morphology. Considering the advantages and disadvantages of conventional chemical and physical methods that are used for preparing TiO2 nanosheets, an optimized scheme for the preparation of TiO2 nanosheets via hydrothermal calcination was proposed. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and UV-visible diffuse reflection absorption spectra (DRS) were used to characterize the structure and morphology of the TiO2 nanosheets, and differences in the photocatalytic water splitting hydrogen production activity of the different calcination temperatures were compared. The suitable calcination temperature of the TiO2 nanosheets was 400°C, and the hydrogen production rate was 270 μmol/h, which indicated that the sheet structure was beneficial for improving the photocatalytic water splitting hydrogen production performance of the material. It is hoped that this work will support the regulation of the surface morphology and surface modification of nanomaterials.

Direct fabrication of electrospun branched nanofibers with tiny diameters for oil absorption

The surface morphology of nanomaterials has been attracting the attention of researchers in order to determine their advantages—related properties. In this work, polyvinylidene fluoride (PVDF) branched nanofibers are directly electrospun with a diameter of less than 35 nm at low relative humidity. The surface morphology and branched structure of as-prepared PVDF webs are characterized. Furthermore, the wettability properties of electrospun fiber webs are demonstrated. The results show that PVDF branched nanofibers have tiny diameters, excellent water contact angle, outstanding specific surface area, and high oil absorption capacity, which exhibit a bright future in the field of oil absorption. We believe this study can be served as a good reference for the preparation, characterization, and application of the branched structure for oil-water separation.

Structure-tunable Mn3O4-Fe3O4@C hybrids for high-performance supercapacitor

Controlling the morphology and structure of nanomaterials is of great importance for enhancing the electrochemical properties. In the paper, Mn3O4-Fe3O4@C hybrids with different architectures were synthesized by incubation of electrospun FeOx-containing carbon fiber (Fe-CNF) in KMnO4 solution followed by annealing. The presence of FeOx on the CNF plays a vital role in determining the morphology and structure of the final hybrids, and the Mn3O4-Fe3O4@C hybrids with half-tube, tube and oolite-filled fibers are formed conveniently by tuning Fe content in the carbon fiber precursor. The good conductivity of fiber and various redox states of Mn and Fe afford the facile charge transfer and excellent reversible redox properties, thus enhancing the capacitor performance. The oolite-filled Mn3O4-Fe3O4@C with tubular structure exhibited a high specific capacitance of 178 F g−1 at a discharge rate of 1 A g−1. This capacitor electrode has an excellent cyclic stability with 95% capacitance retention after 1000 cycles at 3 A g−1. This work provides a very simple strategy to tune the unique nanostructures of metal oxide on Fe-CNF for high-performance supercapacitor application in the future.

Oxidized Black Phosphorus Nanosheets as an Inorganic Antiresorptive Agent

Black phosphorus (BP) is a newly discovered two-dimensional material that has promising applications from bioelectronics to biomedicine. However, facile oxidation of BP leads to changes in surface ...

Remarkable Thermal Conductivity Enhancement in Carbon-Based Ionanofluids: Effect of Nanoparticle Morphology.

Transfer of the excellent intrinsic properties of individual carbon nanoparticles into real-life applications of the corresponding heat transfer fluids remains challenging. This process requires identification and quantification of the nanoparticle–liquid interface. Here, for the first time, we have determined geometry and properties of this interface by applying transmission electron cryomicroscopy (cryo-TEM). We have systematically investigated how the particle morphology of carbon-based nanomaterials affected the thermal conductivity, specific isobaric heat capacity, thermal diffusivity, density, and viscosity of ionanofluids and/or bucky gels, using a wide range of fillers, especially single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs), both with extreme values of aspect ratio (length to diameter ratio) from 150 to 11 000. Accordingly, hybrid systems composed of various carbon nanomaterials and ionic liquid, namely 1-ethyl-3-methylimidazolium thiocyanate [EMIM][SCN], were prepared and characterized. Most of the analyzed nanodispersions exhibited long-term stability even without any surfactant. Our study revealed that the thermal conductivity could be remarkably improved to the maximum values of 43.9% and 67.8% for ionanofluid and bucky gel (at 1 wt % loadings of MWCNTs and SWCNTs), respectively, compared to the pristine ionic liquid. As a result, the model proposed by Murshed and co-workers has been improved for realistic description of the concentration-dependent thermal conductivity of such hybrid systems. The obtained results undoubtedly indicate the potential of ionanofluids and bucky gels for energy management.

One-Pot Hydrothermal Preparation of Fe3O4 Decorated Graphene for Microwave Absorption.

Fe3O4 decorated graphene was synthesized for electromagnetic wave absorption via a facile one-pot hydrothermal approach. The structure and morphology of the as-prepared nanomaterials were systematically investigated. The graphene oxide (GO) was reduced and Fe3O4 nanoparticles were evenly decorated on the surface of reduced graphene oxide (rGO) nanosheets. The average particle size of Fe3O4 nanoparticles is about 15.3 nm. The as-prepared rGO-Fe3O4 nanocomposites exhibited a good microwave absorption performance because of the combination of graphene and magnetic Fe3O4. When the thicknesses are 1.6 mm and 6.5 mm, the reflection loss (RL) values are up to −34.4 dB and −37.5 dB, respectively. The effective bandwidths are 3.8 and 1.9 GHz.

Hierarchical Nanorods of MoS2 /MoP Heterojunction for Efficient Electrocatalytic Hydrogen Evolution Reaction.

Hierarchical nanostructures with tailored component and architectures are attractive for energy-related applications. Here, the delicate design and construction of hierarchical MoS2 /MoP (H-MoS2 /MoP) nanorods for the hydrogen evolution reaction (HER) are demonstrated. This multiscale design rationally combines the compositional and structural advantages of MoS2 /MoP heterojunction into a hierarchical architecture, which can modulate electronic structure of S, remarkably facilitating the electrocatalytic HER. Benefitting from their unique architecture and electronic structure, the H-MoS2 /MoP nanorods exhibit excellent performance for HER with ultralow overpotential of 92mV at current density of 10mA cm-2 in 1 m KOH and high stability. This work not only provides an efficient approach to constructing hierarchical heterojunctions, but also a multiscale strategy for all-round regulation of the electronic structure and hierarchical morphology of nanomaterials for energy-related applications.

Tailoring morphology and structure of manganese oxide nanomaterials to enhance oxygen reduction in microbial fuel cells

In this study, 1D structures based on α-MnO2 nanowires and β-MnO2 nanorods were fabricated by a single-step hydrothermal synthesis and evaluated as cathode components for microbial fuel cells (MFCs). The role of crystallinity and morphology on electrocatalytic activity was investigated by combining X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy with an electrochemical analysis of oxygen reduction reaction at the surface of MnO2-based structures. Among the synthesized composites, β-MnO2 nanorods showed higher ORR activity thanks to the synergy between the rod-like morphology and the nitrogen presence in/on the carbon support which provides a more accessible surface for oxygen adsorption and consequent reduction. MFCs assembled with β-MnO2 nanorod cathode allowed achieving a maximum power density of 524 ± 3 mW m−2 and superior cycling stability as compared to α-MnO2 nanowires and control Pt/C.

Au@Rh core-shell nanowires for hydrazine electrooxidation

Optimizing morphology, structure, and composition of noble metal bimetallic nanomaterials not only enhances their electroactivity and stability but also expands their scope of application. In this work, ultrafine bimetallic Au@Rh core-shell nanowires (Au@Rh ultra-NWs) are synthesized by simple wet chemical strategy using ultrafine Au nanowires (Au ultra-NWs) with 5.50 nm diameter as substrate and explore their potential application for hydrazine electro-oxidation reaction (HeOR) in an alkaline solution. Experimental and calculational results demonstrate that bimetallic Au@Rh ultra-NWs with optimal component reveal 13.6-fold Rh-mass activity enhancement for HeOR at 0.4 V potential relative to commercial Rh nanocrystals (Rh c-NCs), which can be ascribed to the ultrathin Rh shell thickness and the electronic effect caused by the interaction between Au core and Rh shell. Under light irradiation conditions, bimetallic Au@Rh ultra-NWs further show plasmon-promoted HeOR activity, which originates from photoelectric and photothermal effects caused by localized surface plasmon resonance of Au ultra-NWs core.

Co-PRECIPITATION SYNTHESIS, CHARACTERIZATION OF CoFE2O4 NANOMATERIAL AND EVALUATION OF ITS TOXICITY BEHAVIOR ON HUMAN LEUKEMIA CANCER K562 CELL LINE

In this study, cobalt ferrite nanomaterial with inverse spinel structure was synthesized via a co-precipitation method using Co(NO3)3.6H2O and Fe(NO3)3.9H2O. A 15% NH4OH solution was used as an alkaline agent for pH adjustment. Oleic acid was used as a coating agent on the surface of the synthesized cobalt ferrite nanoparticles. PXRD analysis confirmed that the obtained material had a main CoFe2O4 cubic crystal structure with space group Fd-3m and lattice parameters a=b=c= 8.40 A (JCPDS standard card no = 01-077-0426). According to the SEM analysis, the pseudo-spherical particles size distribution and morphology of the as-synthesized nanomaterial were homogeneous. The magnetic behavior of the obtained material was analyzed by vibrating-sample magnetometer (VSM). Besides, anti-cancer effect of the as-synthesized cobalt ferrite nanoparticles was examined on an experimental model of acute myeloid leukemia (CML) K562 cell line for the first time. Inhibition of cell growth and cytotoxicity (apoptosis) that are characteristics features of cobalt ferrite nanoparticles are tested on K562 cell line. The results showed growth and viability inhibition and induction of apoptosis in K562 cells treated with the nanoparticles.

Effects of hydrogen/carbon molar ratio on graphene nano-flakes synthesis by a non-thermal plasma process

Few-layer graphene nano-flakes (GNFs) are successfully prepared via hydrocarbon pyrolysis using a non-thermal plasma process based on a magnetically stabilized gliding arc discharge (MSGAD) at atmospheric pressure. The effects of feedstock gas type and hydrogen flow rate on the morphology of carbon nanomaterials are investigated. When the hydrogen/carbon (H/C) molar ratio is 4, the synthesized GNFs consist of 10 layers per stack with dimensions between 100 and 300 nm in a 4.57.2% yield. The energy cost is 0.1–0.2 kWh/g, which makes this process feasible for large-scale GNFs production. The results show that appropriately increasing the H/C molar ratio promotes the morphological transformation of carbon nanomaterials from spherical carbon nanoparticles (SCNs) to GNFs, improve the quality of GNFs and reduce the stacking of graphite layers. However, increasing the H/C ratio reduces the yields of carbon nanomaterials, so as to increase the energy cost. Analysis suggests that increasing the H/C ratio reduces the concentration of polycyclic aromatic hydrocarbon (PAH) and generates more H atoms, which helps form a two-dimensional nucleation and promotes planar growth. However, an excessive H/C ratio may introduce some defects due to an etching effect.

DL-Valine assisted fabrication of quercetin loaded CuO nanoleaves through microwave irradiation method: Augmentation in its catalytic and antimicrobial efficiencies

The DL-valine stabilized CuONL’s were prepared by a facile greener microwave method and characterized by UV–vis absorption spectroscopy, IR, XRD, TEM and TGA analysis. The morphology of CuO nanomaterial was controlled by varying the microwave irradiation time and using two stabilizers DL-valine and sodium dodecyl sulphate. FESEM and EDX techniques were used for the purity analysis of CuONL’s. The BET surface area and porosity of nanomaterial was investigated by BET analysis. The catalyst exhibited excellent catalytic efficiency for the photocatalytic degradation of toxic dyes malachite green and methyl violet. The percentage degradation of malachite green and methyl violet was found to be 94.4 % and 92.4 % respectively. The catalyst also exhibited enhanced activity for the reduction of aromatic nitro compounds. Anticancer and antimicrobial activities of the CuO NL’s were evaluated after loading them with quercetin. The quercetin loading efficiency confirmed with TGA and was found to be 20.71 %. The time kill experiment showed that quercetin loaded NL’s have stronger antimicrobial potential as compared to pure CuO NL’s. Also, the material was found to be effective against A549, MCF7 and K-562 cancer cell lines.

Influence of metallic species for efficient photocatalytic water disinfection: bactericidal mechanism of in vitro results using docking simulation.

TiO2-based heterogeneous photocatalysis systems have been reported with remarkable efficiency to decontaminate and mineralize a range of pollutants present in air and water medium. In the present study, a series of visible light active metal oxide TiO2 nanoparticle were synthesized and evaluated for their photodegradation efficiency against emerging textile pollutant (Reactive Yellow 145) and antibacterial applications. In the first phase, nanomaterial synthesis was carried out following various synthesis parameters like addition of metallic impurities (different types and concentration) and calcination temperature. In the second phase, synthesized nanomaterials were screened for their performance in terms of photocatalytic degradation of RY145 and the best one (Fe-1-T-3 with 100% RY145 removal within 80min of irradiation) was further optimized against various reaction parameters. To get knowledge about the insights of nanomaterial performance for degradation of different environmental pollutants, the most important is to understand their physicochemical properties utilizing different characterization techniques. The physical morphology and elemental dispersion of metal-doped TiO2 nanomaterials were analyzed and results indicated that added metallic impurities were well dispersed onto the substrate surface. The efficient nanomaterials selected from initial screening were further assessed for photocatalytic disinfection efficiency against human pathogenic bacterial strains. Antimicrobial activities of the metal oxide nanomaterial were tested against gram-positive and gram-negative pathogenic bacterial strains. Possible mode of interaction of nanomaterial with bacterial DNA for bacterial cell inactivation was predicted using molecular docking simulation. The research project has the potential to contribute to multiple disciplines like material synthesis, water disinfection, and as green solutions for the textile industry replacing traditional technologies.

Nanostructured Spin Ladder Compound CaCu2O3 based Gas Sensor for the Detection of Volatile Organic Compounds

Several volatile organic compounds (VOCs) are found in human breath and the concentrations of such VOCs are usually measured to be at sub-ppm level or even lower for healthy human beings. Abnormal concentrations of the breath VOCs are reported to correlate with unhealthy/injurious body/organ conditions; for instance, acetone gas for diabetes, trimethylamine for uremic patients and ammonia gas for renal disease. Hence, VOCs can potentially be used as disease-specific biomarkers for non-invasive early detection or monitoring from breath. Acetone can be produced via the fatty acid oxidation in diabetes and ketoacidosis lack of insulin. Excessive acetone circulating in the blood system is excreted from the lungs. Higher acetone concentration ranges from 1.7 ppm to 3.7 ppm could be detected in breath for those who are diabetic, while the breath of healthy human typically contains less than 0.8 ppm. Gas sensors with sub-ppm acetone detection capacity play an important role in the development of non-invasive monitors or early diagnosis of potential diabetic patients. Up to date, various gas sensors have been successfully developed to detect acetone by controlling the morphology of nanomaterials or introducing the noble metals into nanoparticles. Although, these sensors had achieved the purpose to detect acetone gas, the high operating temperature, higher-energy cost, and the long response time still limit their further applications in practice. Great effort has been made to improve that, by choosing novel material. In order to solve these problems, the present work will focus on the design and development of gas sensors based on new nanomaterials CaCu2O3 offer extremely large surface-to-volume ratio, and the possibility to modify their surface reactivity to attain high sensitivity at low concentration (ppt or lower) required for detection of acetone.CaCu2O3 nanoparticles were synthesized by microwave irradiation method. The structural, morphological, electrical properties were studied by HRSEM, XRD and electrical measurements. The response of CaCu2O3 sensors to acetone at different operating temperatures is reported. It can be noted that the maximum of response to acetone observed at 200°C. The resistance change of the sensor to temperature change is quick and the baseline stabilization is attained in a brief time. The response of the sensor to acetone pulses is reversible and fast (τres ~ 5 seconds). Further, a considerable decrease has been observed in the recovery time (τrec ~ 20 seconds), which is another key advantage of this CaCu2O3.The reproducibility and repeatability are other important factors for a acetone gas sensor. The cycling performance of the fabricated sensor at 200°C shows that the response to 100 ppm of acetone is the same when the measurements were repeated for 10 times consecutively, indicating the excellent reproducibility. Furthermore, the long-term stability of the sensor was also evaluated for many months, and the responses are nearly the same, demonstrating the good stability of the developed sensor.CaCu2O3 nanorods have been prepared by microwave irradiation method and their gas sensing properties towards acetone and ethanol are investigated. All the fabricated sensors show reversible resistance changes while exposed to acetone. The gas sensing measurements of CaCu2O3 sensor exhibited high sensitivity and good selectivity towards acetone. Further, the fabricated sensor showed remarkable increase in sensor response and recovery times. The developed CaCu2O3 sensor is most promising candidate for highly sensitive and selective detection of acetone for medical applications.