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► The paper emphasizes the heat stable bioreductant present in the plant extracts for the synthesis of nanoparticles. ► The research highlights in the paper is included elaborated ...procedures and review in this aspect. ► The nanobiotechnological and medical application work in the plant,
Mentha piperita at the first time. ► This is a one among few plant has role to synthesis of both silver and gold nanoparticles. ► To the best of our knowledge, this may be the first report on sterilized plant extract has been used in this direction and antibacterial property also been observed from the synthesized nanoparticles against clinical pathogens.
Biosynthesis of nanoparticles is under exploration is due to wide biomedical applications and research interest in nanotechnology. Bioreduction of silver nitrate (AgNO
3) and chloroauric acid (HAuCl
4) for the synthesis of silver and gold nanoparticles respectively with the plant extract,
Mentha piperita (Lamiaceae). The plant extract is mixed with AgNO
3 and HAuCl
2, incubated and studied synthesis of nanoparticles using UV–Vis spectroscopy. The nanoparticles were characterized by FTIR, SEM equipped with EDS. The silver nanoparticles synthesized were generally found to be spherical in shape with 90
nm, whereas the synthesized gold nanoparticles were found to be 150
nm. The results showed that the leaf extract of menthol is very good bioreductant for the synthesis of silver and gold nanoparticles and synthesized nanoparticles active against clinically isolated human pathogens,
Staphylococcus aureus and
Escherichia coli.
We report the fabrication of one dimensional Silicon nanowires (Si NWs) using p-Si (100) substrate through facile two step metal assisted chemical etching (MACE) approach. The evolution of structural ...and optical properties of Si NWs by etching Si substrate was studied as a function of hydrogen peroxide (H2O2), a strong oxidation agent. The length of the NWs increased linearly with the H2O2 concentrations and reached maximum of 51 μm for etching of 60 min. The merits of metal free Si NWs as photocathode in the photoelectrochemical (PEC) neutral water splitting under the visible light was investigated. The performance of the photocathode highly depends on the morphology of Si nanostructure. A high density and well separated Si NWs fabricated by 0.6 M of H2O2 results in maximum photocurrent density of 6 mA cm−2 with applied bias photocurrent conversion (ABPE) efficiency of 1.1% under visible light illumination.
•Fabrication of Si NWs through MACE method by varying the concentrations of H2O2.•Etching rate resolve the Si NWs morphology, length and anti-reflectance properties.•Si NWs as efficient photocathode in PEC properties were investigated.•Maximum photocurrent density of 6 mA cm−2 with 1.1% ABPE using Si NWs.
Herein, we report the fabrication of nanocrystals activated 1D TiO2 nanorods heterostructure photoanode with top-open vertical photoanode structure by hydrothermal and SILAR method. The vertical ...nanorod heterostructure could effectively manifest the interface with electrolyte and photoanode for dynamic water oxidation. Furthermore, thermodynamically stable TiO2 nanorod and its conduction band alignment with CdS and CdSe nanocrystals uphold the charge separation and culminate the photocurrent density to 2.01 mA cm−2 at 1.23 V RHE. The decoration of CdS and CdSe co-crystals on TiO2 exhibited a significantly enhanced photoresponse and clear evidence of the negative shift of onset-potential with a five-fold increment of solar to hydrogen generation.
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•TiO2/CdS/CdSe heterostructure photoanodes accomplish enhanced water splitting activity under visible light.•The vertically opened bi-junction heterostructure achieve high surface area and swift electron-hole separation.•The photoanodes can be fabricated via trouble-free facile methods.•The fabrication of TiO2/CdS/CdSe heterostructure is an exceptional strategy for solar to hydrogen conversion.•The charge carrier transfer mechanism for the enhanced watersplitting activity is clarified.
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•Hydrothermal synthesis of porous structured SrTiO3 for solar cell device.•Novel optical properties of porous structured SrTiO3.•Morphology determination of SrTiO3 by ...FE-SEM.•Identification of function group through FTIR.•I-V characteristic observation from the synthesized porous SrTiO3.
Porous strontium titanate (SrTiO3) is synthesized by the hydrothermal interaction of strontium acetate and titanium isopropoxide. X-ray diffraction confirms the formation of cubic structured SrTiO3 particles. The field emission scanning electron microscope reveals the highly ordered mesoporous particles with a pore size of ∼42nm. The vibrational spectra of SrTiO3 are analyzed by Raman and Fourier Transform Infrared techniques. The porous SrTiO3 particles exhibits strong first order Raman scattering which is normally absent in bulk SrTiO3 crystal due to breaking of symmetry. A green emission around 536nm observed in the photoluminescence spectrum indicates the existence of self trapped excitons (STE). A sandwich type Eosin Yellow sensitized solar cell is prepared using porous SrTiO3 exhibits excellent diode characteristics with improved photovoltage of 0.73V.
We report on the enhanced photoelectrochemical water splitting of hybrid ZnS/ZnO core-shell nanorod arrays functionalized with Bi2S3 nanosheets as photoanode. The ZnO nanorod arrays were prepared by ...a facile hydrothermal approach and sulphurized to form ZnS shell. Subsequently porous Bi2S3 nanosheets were arbitrarily decorated on the nanorod arrays by ionic adsorption and reaction method. Substantial enhancement in photocurrents with twofold increment is observed for hybrid photoanode compared to pristine counterparts. The structural and morphological properties of nano hybrid Bi2S3/ZnS/ZnO samples were analyzed by field emission scanning electron microscopy and X-ray diffraction. The higher wavelength shift in the absorption edge of Bi2S3/ZnS/ZnO photocatalyst was observed in diffuse reflectance UV–Visible spectra. The low temperature photoluminescence and impedance spectra of Bi2S3/ZnS/ZnO photoanode confirm that Bi2S3 functionalization reduces the recombination of electron–hole pair and facilitates barrier free charge transfer. The Bi2S3/ZnS/ZnO photoanode device exhibits photocurrent density of 220 μA/cm2 at 0.2 V vs. Ag/AgCl under the electrolyte solution at pH ~10.8. The resultant hybrid photoanode withhold good stability and maintain the facile charge carrier generation and separation. Bi2S3 topological nanosheets are responsible for the absorption of complete visible photons while ZnS/Bi2S3 inter-junction provides the robust electron-hole pair separation at their interface due to infiltration pathway. The photoactive hybridization of Bi2S3/ZnS/ZnO provokes the enhanced donor charge density for efficient hydrogen evolution reaction.
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•2D Bi2S3 anchored 1D ZnS/ZnO core-shell photoanode fabricated.•2D Bi2S3 staging enhances the photo-electrochemical properties.•Bi2S3/ZnS/ZnO shows stable photocurrent density of 220 μA/cm-2.•Bi2S3/ZnS/ZnO enhances the photo-electrocatalytic water oxidation.
We report the role of surface coverage of gold nanoparticles (AuNPs) at the interface of anode/hole transport layer (HTL) in organic light emitting devices (OLEDs). AuNPs with an optimized coverage ...of 2.10% at the ITO/α-NPD interface increase the hole injection into the HTL which results in three orders of magnitude enhancement in the current density in OLEDs. At low surface coverage, injected holes are trapped at the interface. The zero field mobility resulting from the Poole–Frenkel equation is responsible for the improved hole injection into the HTL layer. The turn-on voltage of OLEDs was efficaciously lowered to 3 V with substantial increment in luminescence. The local field generated by AuNPs under electrical biasing with sufficient coverage is ascribed to the improved characteristics in OLEDs.
Interfacing an electrocatalyst with photoactive semiconductor surfaces is an emerging strategy to enhance the photocathode performance for the solar water reduction reaction. Herein, a core-shell ...heterostructure photocathode consisting of vanadium disulfide (VS2) as a 2D layered electrocatalyst directly deposited on silicon nanowire (Si NWs) surface is realized via single-step chemical vapor deposition towards efficient hydrogen evolution under solar irradiation. In an electrochemical study, 2D VS2/Si NWs photocathode exhibits a saturated photocurrent density (17 mA cm−2) with a maximal photoconversion efficiency of 10.8% at −0.53 V vs. RHE in neutral electrolyte condition (pH∼7). Under stimulated irradiation, the heterostructure photocathode produces a hydrogen gas evolution around 23 μmol cm−2 h−1 (at 0 V vs. RHE). Further, electrochemical impedance spectroscopy (EIS) analysis reveals that the high performance of the core-shell photocathode is associated with the generation of the high density of electron-hole pairs and the separation of photocarriers with an extended lifetime. Density functional theory calculations substantiate that core-shell photocathodes are active at very low Gibbs free energy (ΔGH*) with abundant hydrogen evolution reaction (HER) active sulphur sites. The charge density difference plot with Bader analysis of heterostructure reveals the accumulation of electrons on the sulphur sites via modulating the electronic band structure near the interface. Thus, facilitates the barrier-free charge transport owing to the synergistic effect of Si NWs@2D-VS2 core-shell hybrid photocatalyst for enhanced solar water reduction performance.
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•VS2 electrocatalyst is successfully deposited on Si NWs surface via CVD approach.•Heterostructure photocathode shows higher PEC water reduction activity at pH∼7.•A maximum saturated photocurrent density (17 mA cm−2) with ABPE 10.8% is achieved.•Si NWs@VS2 DFT analysis shows low Gibbs free energy of adsorption hydrogen (ΔGH*).
We present the fabrication of self-assembled wurtzite gallium nitride (GaN) nanostructures with manifold morphologies through chemical vapor deposition under controlled deposition conditions. The ...different nanostructures including vertical standing whiskered nanowires (NWs), entangled NWs, nanorods, micro/nanotowers, highly transparent ultrathin nanosheets, and hexagonal microcrystals were evolved by the direct reaction of metal Ga with NH3 using a self-catalytic process by varying the important growth parameters such as temperature, source to substrate distance, and the reactor pressure. The growth mechanism of GaN nanostructures with manifold morphologies was interpreted with a surface diffusion model by accounting the direct impingement and surface migration of adatoms. Electron microscopy studies combined with a selected area electron diffraction pattern recorded on the NWs show wurtzite structure with preferential growth direction of (0001). X-ray diffraction studies on different nanostructures show that the hexagonal GaN contains neither cubic GaN nor Ga2O3 phases. Room temperature photoluminescence spectra reveal high optical quality of the nanostructures grown under either equimolar ratio or slightly nitrogen-rich regime, and, interestingly, GaN microcrystals grown under Ga-rich conditions were dominated by the defect induced green and yellow luminescence.
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•Graphene oxide (GO) resistive memory performances have improved by hydrogen plasma.•Increased on/off ratio demonstrated in GO resistive memory by H-plasma.•H-plasma establish thin ...interfacial layer at GO/Al for enhanced electron transport.•Oxygen reduction in GO corroborated with Raman, XPS and Impedance spectroscopy studies.
We report the improved performance of graphene oxide (GO) based resistive random-access memory devices (ReRAM) through mild hydrogen plasma treatment. The threshold voltage of the ReRAM device is successfully reduced from 2.6 to 1.8 V together with an enhanced ON/OFF ratio of 103 with the help of hydrogen plasma treated GO (HGO). Significantly, the rise of a weak 2D band in Raman spectrum of HGO reveals the mild reduction of GO by H2 plasma. The concurrent removal of oxygen moieties on basal plane and on edges of graphitic network in GO by the virtue of H2 plasma is argued to contribute enhanced performance in ReRAM devices. The significant diminution of oxygen moieties on GO lattice in HGO infused device reduces the insulating barrier formed at Al/GO interface which reinforced the electron transport. The effective selection of plasma treatment is found to be one of the proficient routes to enhance the storage capabilities of GO based resistive memory devices.
We report a novel class of silicon nanowire-based hybrid heterostructures consisting of perovskite SrTiO3 nanoparticle-coupled g-C3N4 nanosheets as a promising photocathode for the solar water ...reduction process. The SrTiO3 nanoparticle-coupled g-C3N4 nanosheets as the interfacial layer with Si NWs provides excellent visible light photocatalytic activity for the proton reduction processes. The hybrid heterojunction photocathode for the water reduction reaction at neutral pH exhibits the highest photocurrent density of 28 mA cm–2, along with a photon-to-current efficiency of 5.4% under visible light irradiation. As a result, the hybrid photocathode shows an unprecedented enhancement in the low photocurrent onset potential (606 mV vs RHE) and hydrogen evolved rate of 18 μmole cm–2 by increasing the interfacial charge carrier separation and the migration process at the photocathode/electrolyte interface. Moreover, the electrochemical impedance spectroscopy studies suggest that the hybrid photocathode holds an impressive charge transfer resistance reduction with an extended lifetime of photoexcited electrons, owing to the well-aligned photocathode/electrolyte interface. The improved photoelectrochemical performances can be ascribed to the high in-built electrostatic field in the interface, and the photocathode is secure from electrolytes by wrapping in an external hybrid sheath. The proposed hybrid Si NWs heterostructure photocathode is expected to provide new opportunities for a very low cost solar energy utilization platform toward a solar-assisted water reduction process.
