Search

This paper succeeded in fabricating and characterizing hybrid nanostructures of Si NWs/graphene and ZnO NPs using pulsed laser deposition (PLD)and by different numbers of pulses (200p, 300p, 400p, 500p). where Characterization of the crystallographic, morphological, and optical properties such as XRD, FE-SEM, AFM and Diffuse reflectance for the synthesized hybrid nanosystems revealed that the addition of graphene and ZnO nanoparticles led to increased roughness values and changes in the surface topography of the membranes. [ABSTRACT FROM AUTHOR]

In this study, we present an efficient method based on vertically oriented silicon nanowire arrays coated with silver nanoparticles to achieve significantly surface enhanced Raman scattering (SERS) signals. The method is applicable for the accurate detection of fungicides and related compounds. The substrates were obtained by a two-step process consisting of the growth of Si nanowire arrays on a silicon wafer by metal-assisted chemical etching and subsequent coating with Ag nanoparticles by the sputtering method. The effect of sputtering time on the growth of nanowires, their morphology and enhancement factor of the signals obtained from the SERS sensor were studied in detail. The final enhancement factor of Raman shift is 1.1 × 107, allowing the limit of trace detection for carbendazim to be as low as 0.1 ppm, with a relative standard deviation of less than 2.07%. This result opens up the potential for direct application of prepared substrates in ultra-fast chemical analysis.

Abstract Ordered hierarchical structured films are considered promising photoanodes for high-performance water-splitting because of their large surface area for light absorption and excellent charge transfer process. In this paper, a novel hierarchical structured photoanode based on growing TiO 2 on a Si nanowire substrate and coupling with Fe 2 O 3 nanothorns was designed and fabricated via a simple method to obtain photoelectrochemical (PEC) properties. The Fe 2 O 3 /TiO 2 /Si nanowire arrays (NWs) were characterized in detail using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectra. The 3D Fe 2 O 3 /TiO 2 /Si hierarchical photoanode exhibited a photocurrent density of 3.5 mA cm−2 at a bias potential of 1.23 V (vs. RHE), which is approximately 87.5 times higher than that of the Si nanowire array (NW) photoanode. The measurement results showed that the improved PEC performance could be attributed to the synergistic effect of the large surface area, low charge transfer resistance, and high charge separation in the hierarchical structure. Highlights • A novel 3D hierarchical Fe 2 O 3 /TiO 2 /Si photoanode was designed and fabricated. • The structural and morphological properties of Fe 2 O 3 /TiO 2 /Si were characterized. • The Fe 2 O 3 /TiO 2 /Si exhibited much higher photocurrent density than that of Si NWs. • EIS was conducted to investigate the properties of the charge transfer process. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the transport properties of silicon nanowires coated with zinc sulfide nanoparticles. Silicon nanowires were prepared by metal assisted electro-less chemical etching technique. The diameter of nanowires varies from 30 to 300nm and length was ∼30μm. Zinc sulfide nanoparticles having diameter ∼30nm were synthesized by co-precipitation method. The nanoparticles were then deposited between the nanowire arrays and most of the nanoparticles stick to the surfaces of the nanowires. The JV characteristics of the devices were investigated from 77 to 300K. The JV characteristics were nonlinear and asymmetric. The decrease in current density in n-silicon nanowires while increase in current density in p + -silicon nanowires were observed when zinc sulfide nanoparticles were coated on them. The decrease in the current density due to the presence of nanoparticles on the walls of the n-silicon nanowires is attributed to enhancement of trapped charge carriers at zinc sulfide nanoparticles and nanowire interface. However increased hole current was observed due to the formation of acceptor like states on the surfaces of p + -silicon nanowires when nanoparticles were coated on them. The detailed carriers transport mechanisms were studied in both types of silicon nanowires. With back to back Schottky diode, Schottky emission mechanism was observed in p + -silicon nanowires while unusual space charge limited current with and without traps was observed in n-silicon nanowires. [Copyright &y& Elsevier]

Silicon nanowires (Si NWs) with and without carbon coating were successfully prepared by combination of chemical vapor deposition and thermal evaporation method. The morphologies, structures, and compositions of these nanomaterials were characterized in detail. Furthermore, the electrochemical performances of uncoated and carbon-coated Si NWs as anode materials were also studied. It shows that the carbon-coated Si NWs electrode has higher capacity, better cycle stability, and rate capability than the uncoated materials. For example, it delivers 3,702 and 3,082 mAh g−1 in the initial charge and discharge processes. When cycled between 0.02 and 2.0 V at a current density of 210 mA g−1, it yields a high coulombic efficiency of 83.2%. The discharge capacity still remains around 2,150 mAh g−1 after 30 cycles. [ABSTRACT FROM AUTHOR]

Abstract Amorphous Si nanowires have been directly synthesized by a thermal processing of Si substrates. This method involves the deposition of an anodic aluminum oxide mask on a crystalline Si (100) substrate. Fe, Au, and Pt thin films with thicknesses of ca. 30 nm deposited on the anodic aluminum oxide-Si substrates have been used as catalysts. During the thermal treatment of the samples, thin films of the metal catalysts are transformed in small nanoparticles incorporated within the pore structure of the anodic aluminum oxide mask, directly in contact with the Si substrate. These homogeneously distributed metal nanoparticles are responsible for the growth of Si nanowires with regular diameter by a simple heating process at 800°C in an Ar-H2 atmosphere and without an additional Si source. The synthesized Si nanowires have been characterized by field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman.