Flake-like Nanostructures Research Articles

Photocatalytic, antioxidant, and antibacterial activities of biocompatible MgO flake-like nanostructures created using Piper betle leaf extract

In this study, biocompatible magnesium oxide (MgO) nanostructures were synthesized using an aqueous solution of Piper betle leaf methanolic extract. The color change during the synthesis process, i.e., colorless to dark brown solution, indicates the formation of MgO nano structures which is further confirmed through UV–Visible spectrum that exhibited characteristic absorption band at 329 nm. Results obtained from morphological analysis reveal that MgO nano flakes (MgO NFs) are present as triangular and polyhedral shapes having an average size ranging between 150 and 200 nm with clear lattice fringes. Secondary metabolites were clearly identified from the FTIR spectrum, and they helped in reduction and stabilization during the synthesis of MgO NFs. The XRD pattern displayed Braggs planes of (111), (220), (220), (311), and (222) with a face centered cubic (FCC) structure, which was further confirmed from the SAED pattern using HRTEM analysis. The as-synthesized MgO NFs manifested profound antimicrobial activity against gram positive as well as gram-negative bacteria with favorable biocompatibility. Furthermore, methylene orange dye was degraded almost completely (98.36 %) in the presence of MgO NFs photo catalysts within 1 h of sunlight illumination. In addition, MgO NFs displayed high level of antioxidant properties with recorded IC50 value of 15.89 μg/ml.

Porous cobalt phosphide nanoflakes supported on ordered mesoporous carbon for superior electrochemical performance supercapacitor and hydrogen evolution reaction

In this study, we synthesized cobalt phosphate flake-like nanostructures anchored to the OMC matrix using a simple and cost-effective hydrothermal process followed by an environmentally friendly phosphidation process. The physicochemical characterization of the CoP@OMC composite indicated that the porous CoP nanoflakes made up of bundles of ultrathin nanosheets with an approximate thickness of 30 nm are anchored on rod-like hexagonal OMC with a diameter of 110–140 nm, allowing remarkable enhancement of mesoporosity and active surface area. The CoP@OMC composite was employed as a new material for modification of electrode surface used in supercapacitor and hydrogen evolution reaction (HER). Interestingly, CoP@OMC acquired a specific capacitance of 3182 Fg−1 at current density of 1 A g−1, in 6 M KOH. Asymmetrical CoP@OMC//CB cell showed a capacity of 194 Fg−1 at the current density of 1 A g−1 with a maximum energy density of 77.9 Wh kg−1 and a power density of 17 kW kg−1. CoP@OMC composite also showed an excellent HER performance with only 111 mV overpotential to drive a current density of 10 mA cm−2 and a low Tafel slope of 43.8 mV dec−1 in 1 M KOH. Therefore, CoP(OMC) as an environmentally friendly material with high efficiency and significant catalytic / electronic properties is expected to be a good candidate for future energy storage & conversion systems.

Synthesis, Characterization, and Antibacterial Properties of ZnO Nanostructures Functionalized Flexible Carbon Fibers.

Studies on the surface functionalization of flexible carbon fibers without any substrate by using cost-effective, fast, and practical processes that may provide antibacterial properties to carbon fiber have received great importance recently. The objective of this patent study is to obtain zinc oxide nanostructures functionalized carbon fibers by a facile, cheap, fast, and repeatable method, and to show their effective antibacterial activity. Electroplating and electrochemical anodization were used to synthesize zinc oxide nanostructures on carbon fiber surfaces, respectively, and their antibacterial properties were studied by zone inhibition test against Staphylococcus aureus and Pseudomonas aeruginosa. The zinc oxide nanostructures on carbon fiber surfaces were successfully synthesized in minutes, and they exhibited effective antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa. The morphological properties of the nanocomposite were studied using scanning electron microscopy, which showed that ZnO on the CF surface exhibits a flake-like nanostructure. Fourier transform infrared spectrophotometer, x-ray diffraction spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy were used to analyze the composite's compositional, structural, crystallographic, and spectral characteristics. The results from all analyses were in a good agreement, indicating that the wurtzite crystalline ZnO nanostructure was successfully produced on the CF surface. As a consequence, a method for the surface functionalization of carbon fiber using zinc oxide nanostructures has been developed that is feasible, low-cost, rapid, and repeatable. The flexible nanocomposite structure has a significant potential to be employed as a scaffold in sensor technology, wearable devices, and particularly in medical textiles due to its antibacterial and woven-able properties.

Optical limiting behavior of metal (Mn, W) oxides decorated nitrogen-doped reduced graphene oxide nanocomposites stimulated by two-photon absorption

Nanopulsed Nd: YAG green laser-induced nonlinear absorption and optical limiting properties of rGO/MnO2, NrGO/MnO2 and NrGO/MnO2/WO3 nanostructures were studied for the first time utilizing single beam Z-scan experiment. Initially, rGO was prepared by solar exfoliation whereas MnO2, WO3, rGO/MnO2, NrGO/MnO2 and NrGO/MnO2/WO3 nanostructures were synthesized by hydrothermal method. XRD was used to determine the structure and crystallite size of the materials. Carbon allotropes and functional groups of the prepared materials were studied using Raman and FT-IR spectroscopy. SEM images showed layered rGO, as well as rod-like MnO2 and flake-like WO3 nanostructures adorned on the top of NrGO layers. EDS analysis validated the presence of C, N, Mn, W, and O. Linear optical study manifested absorption in the UV–Visible region between 200 nm and 800 nm. The occurrence of reverse saturable absorption (RSA) was confirmed by an open aperture Z-scan technique. Compared to its pure analogs and derivatives of graphene, MnO2 decorated NrGO had a higher two-photon absorption coefficient (8.92 × 10−11 m/W) and the lowest optical limiting (OL) threshold (3.29 × 1012 W/m2). Extensive conjugation for charge transfer in NrGO and rod-like shape, homogeneous decorating, and strong visible absorption in MnO2 combine to provide enhanced nonlinear optical (NLO) response and has the potential use in energy stabilizers and laser safety devices in the 532 nm, 9ns laser domain.

Highly conducting flake-like CuS nanostructured counter electrode for photoelectrochemical solar energy conversion

Fabrication of platinum (Pt) free, low cost, environmentally friendly counter electrode is highly attractive for electrochemical solar energy conversion. In this report, highly conducting flake-like CuS nanostructured counter electrode has been prepared for photosensing study and semiconductor sensitized solar cell application. Flake-like CuS nanostructures were synthesized by sulfuration of CuO nanorods grown by hydrothermal process. Scanning electron microscopy and atomic force microscopy study confirmed the growth of flake-like CuS nanostructures on glass substrates. CuS nanoflakes were highly crystalline with hexagonal phase. The various electronic states of Cu and S in CuS nanoflakes were studied using X-ray photoelectron spectroscopy. Chemically grown CuS films were highly conducting and highest conducting film was obtained at 85°C growth temperature with sheet resistance ∼20.02±0.02Ω/sq. Photoelectrochemical solar cell (PEC) was fabricated using CdS decorated TiO2 nanorods as working electrode and CuS film as counter electrode. The short circuit current density, open circuit voltage and power conversion efficiency of the PEC device were found to be ∼4.8 A/m2, ∼0.38 V and ∼0.17%, respectively.

Flake-like CuO nanostructure coated on flame treated eucalyptus wood evaporator for efficient solar steam generation at outdoor conditions

The conversion of solar light to heat for solar driven steam generation is familiar for purification of water and energy storage. Natural Eucalyptus wood used as the new substrate for photo thermal materials in solar steam generation owing to strong adaptability, thermal insulation, vertically aligned water transport channel, growth naturally, low-cost, and renewability. In the present study, various samples, namely Eucalyptus wood (EW), flame-treated eucalyptus wood (FTEW), CuO coated eucalyptus wood (CuO EW) and CuO coated flame-treated eucalyptus wood (CuO FTEW) are experimentally investigated to study the performance of solar desalination at outdoor conditions. As a part of the study, CuO nanomaterial is synthesized and characterized using XRD, UV-Vis, FTIR, and FE-SEM which confirms that CuO has a crystallite size of ̴18 nm, excellent light absorbing behaviour, functional group and flake-like structure respectively. Here, the light absorption and porous structure of CuO FTEW fulfil the fundamental requirement of solar steam generation. The maximum evaporation efficiency of CuO FTEW sample is 85.6% at outdoor condition (q = 492 W/m2) owing to the presence of evenly distributed CuO flakes on the surface of wood, carbon content and capillary action. Eventually, the mechanically robust, low cost, environmentally sustainable and long-term stability of CuO FTEW presents great opportunity for desalination and waste water treatment.

Hydrophilic ionic liquid assisted hydrothermal synthesis of ZnO nanostructures with controllable morphology.

Nanostructured ZnO with controllable morphology was prepared by a hydrothermal method in the presence of three different hydrophilic ionic liquids (ILs), 1-ethyl-3-methylimidazolium methylsulfate, ([C2mim]CH3SO4), 1-butyl-3-methylimidazolium methylsulfate, ([C4mim]CH3SO4) and 1-ethyl-3-methylimidazolium ethylsulfate, ([C2mim]C2H5SO4) as soft templates. The formation of ZnO nanoparticles (NPs) with and without IL was verified using FT-IR and UV-visible spectroscopy. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns indicated the formation of pure crystalline ZnO with a hexagonal wurtzite phase. Field emission scanning electron microscopic (FESEM) and high-resolution transmission electron microscopic (HRTEM) images confirmed the formation of rod-shaped ZnO nanostructures without using IL, whereas the morphology varied widely following addition of ILs. With increasing concentrations of [C2mim]CH3SO4, the rod-shaped ZnO nanostructures transformed into flower-shaped nanostructures whereas with rising concentrations of [C4mim]CH3SO4 and [C2mim]C2H5SO4 the morphology changed into petal- and flake-like nanostructures, respectively. The selective adsorption effect of the ILs could protect certain facets during the formation of ZnO rods and promote the growth in directions other than [0001] to yield petal- or flake-like architectures. The morphology of ZnO nanostructures was, therefore, tunable by the controlled addition of hydrophilic ILs of different structures. The size of the nanostructures was widely distributed and the Z-average diameter, evaluated from dynamic light scattering measurements, increased as the concentration of the IL increased and passed through a maximum before decreasing again. The optical band gap energy of the ZnO nanostructures decreased when IL was added during the synthesis which is consistent with the morphology of the ZnO nanostructures. Thus, the hydrophilic ILs serve as self-directing agents and soft templates for the synthesis of ZnO nanostructures and the morphology and optical properties of ZnO nanostructures are tunable by changing the structure of the ILs as well as systematic variation of the concentration of ILs during synthesis.

Millettia pinnata plant pod extract-mediated synthesis of Bi2O3 for degradation of water pollutants.

In this study, plant extract obtained from pods of Millettia pinnata plant species was employed for nanosynthesis of Bi2O3. The as-synthesized semiconductor metal oxide nanoparticles were analyzed using various characterization tools such as X-ray diffraction (XRD), Scanning electron microscope (SEM), ultra violet-visible (UV-Vis), Fourier transform infrared (FTIR), Zeta potential, Raman, and X-ray photoelectron spectroscopy (XPS). The characterization results designate the formation of α and β forms of Bi2O3. FESEM images demonstrate rod and flake-like nanostructures ranging from 25 to 70nm. The green synthesized nanomaterial was found efficient for reduction of 4-nitro phenol (4-NP) and 4-nitro aniline (4-NA). However, it showed better performance toward the reduction of 4-NA. Photocatalytic investigations demonstrated that the green synthesized nanophotocatalyst was capable in degrading Amido Black 10B (AB-10B) dye efficiently under visible light illumination. 98.83% degradation of AB-10B dye was achieved within 120min of irradiation under optimum conditions of photocatalyst dose and dye concentration. Active species trapping experiments revealed prominent role of superoxide radicals (•O2-) while hydroxyl radicals (•OH) played considerable role in the AB-10B photocatalytic degradation process. Moreover, the photostability and reusability assessment study ascertained good performance of the catalyst afterfour runs of successive cycles.

Covellite nanoparticles with high photocatalytic activity bioproduced by using H2S generated from a sulfidogenic bioreactor

The application of sulfate reducing bacteria (SRB) has emerged as an efficient biotechnology to reduce sulfate to sulfide and to mediate the precipitation of transition metals as sulfides. In the present work, hydrogen sulfide biogenerated by the SRB was delivered into a copper aqueous solution vessel to produce copper sulfide nanoparticles. The main physico-chemical properties were studied by TEM, XRD, UV–vis spectroscopy, fluorescence spectroscopy, UPS and XPS. In addition, the photocatalytic activities for organic dyes removal were investigated, showing a high degradation rate of MB and RD in aqueous solution. By changing the copper concentration during the synthesis process, main physico-chemical properties of copper sulfides nanoparticles can be controlled. For the lowest concentration, pure covellite flake-like nanostructures were produced. Higher concentrations produced spherical-like shapes with the presence of SO42− on the surface. Experimental results showed a promising way to obtain valorous copper sulfides nanoparticles by using dissimilatory reduction of sulfate mediated by SRB.

Growth of nanostructured cobalt sulfide-based nanocomposite as faradaic binder-free electrode for supercapattery

The intermittent nature of renewable energy needs ideal storage device to balance the electricity demand and supply. Specific energy, specific power, and stability of electrode play a critical role to increase better performance of supercapattery. Here, we account a unique cobalt sulfide (CoS) binder-free electrode which was modified with different metals (i.e. manganese (Mn) and copper (Cu), fabricated by hydrothermal technique on the nickel foam (NF). The morphological features portray uniform distribution of flakes with different textures after the incorporation of Mn and Cu with the optimised cobalt sulfide system, respectively. Among all electrodes, Mn-CoS-3/NF exhibits a significant boost in the rate capability at 74% compared to CoS-3/NF (75%) and Cu-CoS-3/NF (59%) electrodes with maximum specific capacitance of 2379 F/g at 1 A/g. Mn-CoS-3/NF also shows capacitance retention about 65% after 5500 cycles compared to CoS-3/NF (48%) and Cu-CoS-3/NF (55%) when performed as three electrode system configurations. The outstanding performance of Mn-CoS-3/NF as compared to the other electrodes is contributed to its high surface area, flake-like nanostructure, valence state of metal, and low internal resistance. In order to evaluate the real time performance of Mn-CoS-3/NF, supercapattery device was fabricated in a configuration of Mn-CoS-3/NF//AC/NF. Mn-CoS-3/NF//AC/NF delivered a specific energy (17.94 Wh/kg at 806 W/kg) and specific power (6405 W/kg at 4.66 Wh/kg). The capacity decayed slowly to 92% after 9000 cycles together with a coulombic efficiency of 99%, indicating good stability of the device.

A room-temperature NO2 gas sensor based on CuO nanoflakes modified with rGO nanosheets

Abstract Conventional gas-sensing materials for detecting trace NO2 gas are suffering from limitations such as low selectivity, high operation temperature and an agglomerated tendency during synthesis. In this work, uniform CuO nanoflakes modified with rGO nanosheets (CuO/rGO) were synthesized via an ultra-low-cost hydrothermal process with a thermal treatment. The gas sensor based on the as-synthesized CuO/rGO was fabricated by spin-coated method and applied to detect ppb-level NO2 gas at room temperature (23℃). Remarkably, the CuO/rGO-based sensor maintained an ultrahigh response behavior of approximately 400.8 % towards 5 ppm NO2 gas with ultrafast response time of 6.8 s at 23℃, and the limit of detection was down to 50 ppb (S = 20.6 %). In addition, the gas sensor had outstanding consistency, reliable repeatability, and long-term stability (30 days). The improved gas-sensing response was attributed to the synergetic effects of CuO and rGO. Specifically, the porous flake-like nanostructures of CuO and high surface areas of CuO/rGO may provide additional active adsorption sites for NO2 gas and accelerate the redox reaction on the surface of CuO/rGO, leading to the ultrahigh response. On the other hand, the rGO nanosheets with excellent transport capability may serve as highly conductive channels to accelerate carrier transfer, which dramatically reduced the response and recovery time. Furthermore, abundant surface defects of CuO/rGO were also conducive to surface reactions in the gas-sensing process. Undoubtedly, the scientific study of the present work will promote potential applications of ppb-level NO2 detection at room temperature.

Potentiostatically deposited bimetallic cobalt–nickel selenide nanostructures on nickel foam for highly efficient overall water splitting

The fabrication of efficient electrocatalysts for water splitting is vital for production of clean fuels. Herein, cobalt–nickel selenide (CoNi2Se4) nanostructures were fabricated on a Ni foam substrate using a facile potentiostatic method at different deposition solution pH levels. Nanoparticle-, fluffy-, and flake-like CoNi2Se4 nanostructures were deposited by changing the aqueous solution pH to 2.0, 2.5, and 3.0, respectively. The desired flake-like CoNi2Se4 electrode fabricated at pH 3.0 presented the best electrocatalytic performance of all CoNi2Se4 nanostructures in this study and required overpotentials as low as 244 and 184 mV to deliver a current density of 10 mA cm−2 for the OER and HER in 1.0 M KOH, respectively. Furthermore, the electrodes presented long-term stability over 20 h at current densities of 10 and −10 mA cm−2. Besides, this bifunctional flake-like CoNi2Se4 electrocatalyst delivered outstanding overall water splitting performance and required an external potential of 1.63 V to deliver a current density of 10 mA cm−2.

Revisiting the Reduction of Thermal Conductivity in Nano- to Micro-Grained Bismuth Telluride: The Importance of Grain-Boundary Thermal Resistance

Nanograined bulk alloys based on bismuth telluride (Bi2Te3) are the dominant materials for room-temperature thermoelectric applications. In numerous studies, existing bulk phonon mean free path (MFP) spectra predicted by atomistic simulations suggest sub-100 nm grain sizes are necessary to reduce the lattice thermal conductivity by decreasing phonon MFPs. This is in contrast with available experimental data, where a remarkable thermal conductivity reduction is observed even for micro-grained Bi2Te3 samples. In this work, first-principles phonon MFPs along both the in-plane and cross-plane directions are re-computed for bulk Bi2Te3. These phonon MFPs can explain new and existing experimental data on flake-like Bi2Te3 nanostructures with various thicknesses. For polycrystalline Bi2Te3-based materials, a better explanation of the experimental data requires further consideration of the grain-boundary thermal resistance that can largely suppress the transport of high-frequency optical phonons.

Effect of NaOH on the preparation of two-dimensional flake-like zirconia nanostructures

The monolayer flake-like zirconia was prepared by a clean molten salt method, which does not require any adsorbent and template. The effects of NaOH on the composition, morphology and structure of zirconia were studied by XRD, IR, Raman, FE-SEM and TEM. The nanostructures synthesized under 2 wt% NaOH exhibit definite flake-like geometry with a large percentage of (001) plane, which measure approximately 1.8 μm long and 80 nm thick. This concomitant phase and morphology change originate from the martensite transformation of metastable tetragonal zirconia. The as-prepared zirconia sheet has potential utility in fields as diverse as chemical adsorption and photocatalysis.

Synthesis and characterization of single phase ZnO nanostructures via solvothermal method: influence of alkaline source

Single phase ZnO nanostructures were synthesized by simple and low temperature solvothermal process from two different alkaline sources; Potassium hydroxide (KOH) and Sodium hydroxide (NaOH) with zinc acetate dihydrate (Zn(CH3COO)2∙2H2O) as precursor. This facile and rapid synthesis technique achieve high purity of Zinc oxide (ZnO) nanostructures on large scale negating the use of complex and high temperature routes. The synthesized particles were characterized by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared (FT-IR) Spectroscopy, Ultraviolet Visible (UV-Vis) spectroscopy and Brunauer-Emmett-Teller (BET) analysis. ZnO synthesized using KOH and NaOH exhibit wurtzite hexagonal and flake-like nanostructures with average crystallite size of 11.0 nm and 14.9 nm respectively. Surface area of 59.50 m2/g and 31.43 m2/g were determined for KOH and NaOH sources respectively. The optical absorption spectra of the two samples showed absorption bands of 367.70 and 365.30 nm. The results showed the effect of alkaline sources on the surface morphology, structural and optical properties of ZnO.

Photocatalytic microreactor using TiO2/Ti plates: Formation of TiO2 nanostructure and separation of oxidation/reduction into different channels

TiO2 is the most popular and promising high-activity photocatalyst and has many applications. Recently, photocatalysis in microreactors has attracted attention due to its effective light irradiation and short diffusion distance. This article introduces our study on the fabrication of TiO2/Ti bilayer plates and their application in a photocatalytic microreactor. First, TiO2 layers with controlled nanostructures were fabricated via the direct oxidation of Ti plates. A network-like and flake-like nanostructure of TiO2 was formed on the surface of Ti plates by alkaline treatment. TiO2 nanotube arrays were formed by anodization of the Ti plate. These TiO2/Ti plates exhibited high photocatalytic performance in the microreactor, which was enhanced by developing the nanostructure. Second, we developed a new photocatalytic microreactor with stacked channels for oxidation and reduction employing the charge separation effect of the TiO2/Ti plate. The UV irradiation of the TiO2-side channel generates pairs of holes and electrons, which are separated by the TiO2/Ti plate and contribute to oxidation and reduction in the different channels. We confirmed the feasibility of this microreactor and demonstrated that the pH difference in the two channels was the important factor enhancing the reduction induced by transferred electrons.

Carbonized metal\u2013organic frameworks with trapped cobalt nanoparticles as biocompatible and efficient azo-dye adsorbent

BackgroundMetal–organic frameworks (MOFs) derived carbonaceous materials functionalized with metal/metal-oxide nanoparticles are obtained by its carbonization. The carbonization of MOFs occurs simultaneously with the metal and metal-oxide particle formation. The carbon-based flake-like nanostructures with trapped metal/metal-oxide nanoparticles have been formed. Due to its non-toxicity and environmental friendliness, the capacity for pollution adsorption using model anionic dye has been revealed.ResultsThe structure of the hybrid is formed as the effect of carbonization of metal–organic frameworks with cobalt as a metal counterpart (CoOF). The cobalt nanoparticles are placed between the carbon layers what limits the dissolution of cobalt nanoparticles and protects the environment from its toxicity. It is preliminary validated by means of two reference micro-organisms (Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus) and in in vitro analysis with human cell line (A375). The efficiency of the adsorption properties of the material was tested with Acid Red 18 as a model anionic dye. The mechanism of dye adsorption was analyzed in details. In addition, various thermodynamic parameters, such as standard enthalpy, standard entropy, and standard Gibbs free energy, were tested. In addition, it was proved that the main substrate of CoOF (terephthalic acid) can be used from PET bottles, while the organic solvent used in its synthesis (N,N-dimethylformamide) was distilled and reused. The obtained carbonized CoOF revealed the same morphology and properties as pristine material.ConclusionsThe kinetic data of dye adsorption fit well with the pseudo-second-order model and Langmuir type. Acid Red 18 adsorption is more favourable at lower temperatures and lower pH. The location of the cobalt nanoparticles between the carbon flakes effectively limits their toxicity compared to the free metal nanoparticles. The CoOF can be obtained from recycled substrates, which revealed the same morphology as pristine material. Therefore, it is believed that this work highlights the practical application of carbonized CoOF as an adsorbate and provides the evidence that such nanocomposite can be applied without environmental risks.

Effects of energy and hydrogen peroxide concentration on structural and optical properties of CuO nanosheets prepared by pulsed laser ablation

Laser ablation of copper targets using Ce:Nd:YAG laser with pulses of 1064 nm wavelengths at 10 ns pulse width and with different laser pulse energies and in different concentrations of H2O2 solution is investigated experimentally. Cu/CuO flake-like nanostructures with visible band gap and the extension of its light absorption by changing the synthesis parameters such as laser pulse energy and concentration of H2O2 solution were observed.Characterization and comparison of the obtained suspensions are exploited by X-ray diffraction (XRD), UV–vis spectroscopy and field emission scanning electron microscopy (FE-SEM). The XRD analysis data show that in 10 vol% H2O2 solution CuO phase has been synthesized, while with decreasing the H2O2 concentration, Cu phase is also observed. The mean crystallite sizes of CuO were estimated using XRD patterns and were between 2.1 and 3.3 nm. The comparison of the UV–visible absorption spectra indicates that with decreasing pulse energy and decreasing H2O2 concentration up to 5 vol% the band gap of nanoparticles increased from 2.19 eV to 2.34 eV, which is accordant with the quantum confinement effect. FESEM image of all the synthesized samples illustrate the formation of flake-like nanostructure with the thickness of about 12–15 nm.

Physical Properties of Sn-Doped PbSe Nanostructures as Photovoltaic Application

This work presents co-precipitation synthesis of tin (Sn)-doped lead selenide (PbSe) nanostructures and their physical properties as a solar cell application. The primary characterization of the obtained samples using X-ray diffraction (XRD) patterns shows the formation of polycrystalline cubic PbSe phase and adding Sn concentration decreased and increased the crystallite size and induced strain, respectively. Morphological studies indicate the formation of flake-like PbSe nanostructures, with Sn atoms decreasing their mean diameter. Optical studies show optical band gap at the proper range for absorbing solar rays as photovoltaic applications. Solar cell devices fabricated from the Sn-doped PbSe nanostructures shows an efficiency (ƞ) of 0.40% for a sample with highest atomic percentage (at%) of Sn. This increasing in efficacy is attributed to various physical features of these structures such as induced strain on the crystalline lattice, a decrease in size, and a shift in the optical energy band gap.

Preparation of a Novel SERS Platform Based on Mantis Wing with High-Density and Multi-Level "Hot Spots".

The recent development of SERS substrates based on irregular nanostructures for directly molecule recognition has aroused increasing attention. By combining the irregular flake-like nanostructures of mantis wings, high SERS performance of Ag nanofilms, and the chemical stability of Au nanoparticles (NPs), an ultra-sensitive and flexible SERS substrate based on Au NPs functionalized Ag nanofilms-mantis wings (Au-Ag-M.w.) hybrid system is successfully fabricated. When 4-aminothiophenol is selected as the probe molecule, the limit of detection (LOD) is as low as 10−13 M and the relative standard deviation (RSD) is lower than 7.15%. This novel SERS platform exhibits high SERS performance in terms of sensitivity, reproducibility and practicability mainly because there are high-density and multi-level “hot spots” in the appropriate nanogaps. Meanwhile, it also systematically compares the differences of the SERS performance of Cu and Ag decorated M.w. hybrids and how these differences can alter their response. Moreover, the proposed substrate is employed to rapidly detect the pesticide residues on apple peels and the LOD for cypermethrin is estimated at 10−10 mg/mL. Therefore, this novel SERS substrate has great potential in rapid sampling of pesticide residues on real samples and expands the investigation to other natural materials for fabricating various SERS platforms.