Tracking of Crystal-Surface-Dependent CuO Nanoparticle Dissolution in an Aqueous Environment.

Metal-oxide-based nanoparticles (MONPs) such as CuO NPs have attracted growing attention, but the potential discharges of MONPs have raised considerable concern of their environmental fate including their dissolution behavior. The impacts of morphology on MONP dissolution are largely uncertain due to the lack of tracking techniques. In this study, we combined a series of technologies including liquid-cell transmission electron microscopy and fluorescence probes to reveal the dissolution process of CuO NPs in freshwater.

Spectroscopic and microscopic examination of teeth exposed to green tea at different temperatures.

Tea is a popular beverage consumed at different temperatures. The effect of tea on teeth at different temperatures has not been studied previously. The present study used an in vitro green tea immersed tooth model at different tea temperatures (hot and cold) compared to an in vivo tea administration model allowing rats to drink tea over the course of a week.

A redox-controlled electrolyte for plasmonic enhanced dye-sensitized solar cells.

Plasmonic enhanced dye-sensitized solar cells (DSSCs) with metallic nanostructures suffer from corrosion problems, especially with the presence of the iodine/triiodide redox couple in the electrolyte. Herein, we introduce an alternative approach by compensating the corrosion with a modified liquid electrolyte. In contrast to the existing method of surface preservation for plasmonic nanostructures, the redox-controlled electrolyte (RCE) contains iodoaurate intermediates, i.

Complementary Metal Oxide Semiconductor-Compatible, High-Mobility, ⟨111⟩-Oriented GaSb Nanowires Enabled by Vapor-Solid-Solid Chemical Vapor Deposition.

Using CMOS-compatible Pd catalysts, we demonstrated the formation of high-mobility ⟨111⟩-oriented GaSb nanowires (NWs) via vapor-solid-solid (VSS) growth by surfactant-assisted chemical vapor deposition through a complementary experimental and theoretical approach. In contrast to NWs formed by the conventional vapor-liquid-solid (VLS) mechanism, cylindrical-shaped PdGa catalytic seeds were present in our Pd-catalyzed VSS-NWs. As solid catalysts, stoichiometric PdGa was found to have the lowest crystal surface energy and thus giving rise to a minimal surface diffusion as well as an optimal in-plane interface orientation at the seed/NW interface for efficient epitaxial NW nucleation.

Water resistant CsPbX nanocrystals coated with polyhedral oligomeric silsesquioxane and their use as solid state luminophores in all-perovskite white light-emitting devices.

We present an approach towards stable solid-state perovskite based luminophores with different emission colors surface protection of CsPbX (X = Br or I) with a polyhedral oligomeric silsesquioxane (POSS). This treatment results in water resistant perovskite nanocrystal powders, and prevents otherwise easy anion exchange between perovskite nanocrystals of different compositions mixed together in the solid state, which allows us to preserve their distinct emission spectra. We subsequently used mixtures of green-emitting POSS-CsPbBr and red-emitting POSS-CsPb(Br/I) nanocrystal powders to fabricate single layer all-perovskite down conversion white light-emitting devices.

Crystal Orientation Controlled Photovoltaic Properties of Multilayer GaAs Nanowire Arrays.

In recent years, despite significant progress in the synthesis, characterization, and integration of various nanowire (NW) material systems, crystal orientation controlled NW growth as well as real-time assessment of their growth-structure-property relationships still presents one of the major challenges in deploying NWs for practical large-scale applications. In this study, we propose, design, and develop a multilayer NW printing scheme for the determination of crystal orientation controlled photovoltaic properties of parallel GaAs NW arrays. By tuning the catalyst thickness and nucleation and growth temperatures in the two-step chemical vapor deposition, crystalline GaAs NWs with uniform, pure ⟨110⟩ and ⟨111⟩ orientations and other mixture ratios can be successfully prepared.

High-Performance GaAs Nanowire Solar Cells for Flexible and Transparent Photovoltaics.

Among many available photovoltaic technologies at present, gallium arsenide (GaAs) is one of the recognized leaders for performance and reliability; however, it is still a great challenge to achieve cost-effective GaAs solar cells for smart systems such as transparent and flexible photovoltaics. In this study, highly crystalline long GaAs nanowires (NWs) with minimal crystal defects are synthesized economically by chemical vapor deposition and configured into novel Schottky photovoltaic structures by simply using asymmetric Au-Al contacts. Without any doping profiles such as p-n junction and complicated coaxial junction structures, the single NW Schottky device shows a record high apparent energy conversion efficiency of 16% under air mass 1.

Approaching the Hole Mobility Limit of GaSb Nanowires.

In recent years, high-mobility GaSb nanowires have received tremendous attention for high-performance p-type transistors; however, due to the difficulty in achieving thin and uniform nanowires (NWs), there is limited report until now addressing their diameter-dependent properties and their hole mobility limit in this important one-dimensional material system, where all these are essential information for the deployment of GaSb NWs in various applications. Here, by employing the newly developed surfactant-assisted chemical vapor deposition, high-quality and uniform GaSb NWs with controllable diameters, spanning from 16 to 70 nm, are successfully prepared, enabling the direct assessment of their growth orientation and hole mobility as a function of diameter while elucidating the role of sulfur surfactant and the interplay between surface and interface energies of NWs on their electrical properties. The sulfur passivation is found to efficiently stabilize the high-energy NW sidewalls of (111) and (311) in order to yield the thin NWs (i.

Control of Emission Color of High Quantum Yield CHNHPbBr Perovskite Quantum Dots by Precipitation Temperature.

are obtained by changing the temperature of a bad solvent during synthesis. The products for temperatures between 0 and 60 °C have good spectral purity with narrow emission line widths of 28-36 nm, high absolute emission quantum yields of 74% to 93%, and short radiative lifetimes of 13-27 ns.

Modulating the morphology and electrical properties of GaAs nanowires via catalyst stabilization by oxygen.

Nowadays, III-V compound semiconductor nanowires (NWs) have attracted extensive research interest because of their high carrier mobility favorable for next-generation electronics. However, it is still a great challenge for the large-scale synthesis of III-V NWs with well-controlled and uniform morphology as well as reliable electrical properties, especially on the low-cost noncrystalline substrates for practical utilization. In this study, high-density GaAs NWs with lengths >10 μm and uniform diameter distribution (relative standard deviation σ ∼ 20%) have been successfully prepared by annealing the Au catalyst films (4-12 nm) in air right before GaAs NW growth, which is in distinct contrast to the ones of 2-3 μm length and widely distributed of σ ∼ 20-60% of the conventional NWs grown by the H2-annealed film.

Surfactant-assisted chemical vapour deposition of high-performance small-diameter GaSb nanowires.

Although various device structures based on GaSb nanowires have been realized, further performance enhancement suffers from uncontrolled radial growth during the nanowire synthesis, resulting in non-uniform and tapered nanowires with diameters larger than few tens of nanometres. Here we report the use of sulfur surfactant in chemical vapour deposition to achieve very thin and uniform GaSb nanowires with diameters down to 20 nm. In contrast to surfactant effects typically employed in the liquid phase and thin-film technologies, the sulfur atoms contribute to form stable S-Sb bonds on the as-grown nanowire surface, effectively stabilizing sidewalls and minimizing unintentional radial nanowire growth.

Low-temperature growth of highly crystalline β-Ga2O3 nanowires by solid-source chemical vapor deposition.

Unlabelled: Growing Ga2O3 dielectric materials at a moderately low temperature is important for the further development of high-mobility III-V semiconductor-based nanoelectronics. Here, β-Ga2O3 nanowires are successfully synthesized at a relatively low temperature of 610°C by solid-source chemical vapor deposition employing GaAs powders as the source material, which is in a distinct contrast to the typical synthesis temperature of above 1,000°C as reported by other methods. In this work, the prepared β-Ga2O3 nanowires are mainly composed of Ga and O elements with an atomic ratio of approximately 2:3.

Carbon dot loading and TiO₂ nanorod length dependence of photoelectrochemical properties in carbon dot/TiO₂ nanorod array nanocomposites.

Photoelectrochemcial (PEC) properties of TiO2 nanorod arrays (TNRA) have been extensively investigated as they are photostable and cost-effective. However, due to the wide band gap, only the UV part of solar light can be employed by TiO2. To enhance the photoresponse of TNRA in the visible range, carbon dots (C dots) were applied as green sensitizer in this work by investigating the effects of C dot loading and length of TiO2 nanorod on the PEC properties of TNRA/C dot nanocomposites.

Crystalline GaSb nanowires synthesized on amorphous substrates: from the formation mechanism to p-channel transistor applications.

In recent years, because of the narrow direct bandgap and outstanding carrier mobility, GaSb nanowires (NWs) have been extensively explored for various electronics and optoelectronics. Importantly, these p-channel nanowires can be potentially integrated with n-type InSb, InAs, or InGaAs NW devices via different NW transfer techniques to facilitate the III-V CMOS technology. However, until now, there have been very few works focusing on the electronic transport properties of GaSb NWs.

Carbon doping of InSb nanowires for high-performance p-channel field-effect-transistors.

Due to the unique physical properties, small bandgap III-V semiconductor nanowires such as InAs and InSb have been extensively studied for the next-generation high-speed and high-frequency electronics. However, further CMOS applications are still limited by the lack of efficient p-doping in these nanowire materials for high-performance p-channel devices. Here, we demonstrate a simple and effective in situ doping technique in the solid-source chemical vapor deposition of InSb nanowires on amorphous substrates employing carbon dopants.

GaAs nanowires: from manipulation of defect formation to controllable electronic transport properties.

Reliable control in the crystal quality of synthesized III-V nanowires (NWs) is particularly important to manipulate their corresponding electronic transport properties for technological applications. In this report, a "two-step" growth process is adopted to achieve single-crystalline GaAs NWs, where an initial high-temperature nucleation process is employed to ensure the formation of high Ga supersaturated Au7Ga3 and Au2Ga alloy seeds, instead of the low Ga supersaturated Au7Ga2 seeds observed in the conventional "single-step" growth. These two-step NWs are long (>60 μm) and thick (>80 nm) with the minimal defect concentrations and uniform growth orientations.

Surface roughness induced electron mobility degradation in InAs nanowires.

In this work, we present a study of the surface roughness dependent electron mobility in InAs nanowires grown by the nickel-catalyzed chemical vapor deposition method. These nanowires have good crystallinity, well-controlled surface morphology without any surface coating or tapering and an excellent peak field-effect mobility up to 15,000 cm(2) V(-1) s(-1) when configured into back-gated field-effect nanowire transistors. Detailed electrical characterizations reveal that the electron mobility degrades monotonically with increasing surface roughness and diameter scaling, while low-temperature measurements further decouple the effects of surface/interface traps and phonon scattering, highlighting the dominant impact of surface roughness scattering on the electron mobility for miniaturized and surface disordered nanowires.

Hierarchical assembly of Ti(IV)/Sn(II) co-doped SnO₂ nanosheets along sacrificial titanate nanowires: synthesis, characterization and electrochemical properties.

Hierarchical assembly of Ti(IV)/Sn(II)-doped SnO₂ nanosheets along titanate nanowires serving as both sacrificial templates and a Ti(IV) source is demonstrated, using SnCl2 as a tin precursor and Sn(II) dopants and NaF as the morphology controlling agent. Excess fluoride inhibits the hydrolysis of SnCl2, promoting heterogeneous nucleation of Sn(II)-doped SnO₂ on the titanate nanowires due to the insufficient oxidization of Sn(II) to Sn(IV). Simultaneously, titanate nanowires are dissolved forming Ti(4+) species under the etching effect of in situ generated HF resulting in spontaneous Ti(4+) ion doping of SnO₂ nanosheets formed under hydrothermal conditions.

Tunable electronic transport properties of metal-cluster-decorated III-V nanowire transistors.

A metal-cluster-decoration approach is utilized to tailor electronic transport properties (e.g., threshold voltage) of III-V NWFETs through the modulation of free carriers in the NW channel via the deposition of different metal clusters with different work function.

Facile synthesis, growth mechanism and reversible superhydrophobic and superhydrophilic properties of non-flaking CuO nanowires grown from porous copper substrates.

Reversible superhydrophobic and superhydrophilic surfaces based on porous substrates covered with CuO nanowires are developed in this study. A facile thermal oxidation method is used to synthesize non-flaking bicrystalline CuO nanowires on porous copper substrates in static air. The effects of thermal oxidation temperature and duration are systemically studied.

Controllable p-n switching behaviors of GaAs nanowires via an interface effect.

Due to the extraordinary large surface-to-volume ratio, surface effects on semiconductor nanowires have been extensively investigated in recent years for various technological applications. Here, we present a facile interface trapping approach to alter electronic transport properties of GaAs nanowires as a function of diameter utilizing the acceptor-like defect states located between the intrinsic nanowire and its amorphous native oxide shell. Using a nanowire field-effect transistor (FET) device structure, p- to n-channel switching behaviors have been achieved with increasing NW diameters.

Synthesis and characterizations of ternary InGaAs nanowires by a two-step growth method for high-performance electronic devices.

InAs nanowires have been extensively studied for high-speed and high-frequency electronics due to the low effective electron mass and corresponding high carrier mobility. However, further applications still suffer from the significant leakage current in InAs nanowire devices arising from the small electronic band gap. Here, we demonstrate the successful synthesis of ternary InGaAs nanowires in order to tackle this leakage issue utilizing the larger band gap material but at the same time not sacrificing the high electron mobility.

Controlled fabrication of core-shell TiO2/C and TiC/C nanofibers on Ti foils and their field-emission properties.

Core-shell TiO(2)/C and TiC/C nanofibers are fabricated in situ on Ti and Al ion-implanted Ti substrates by a thermochemical reaction in acetone and the growth mechanism is described. Implantation of Al into Ti leads to in situ growth of TiC/C in lieu of TiO(2)/C nanofibers. This is because Al has a higher affinity to oxygen than Ti and Ti reacts preferentially with C to form TiC.