Surface Capping Research Articles

Effects of SiOx barrier layer prepared by plasma-enhanced chemical vapor deposition on improvement of long-term reliability and production cost for Cu-plated amorphous Si/crystalline Si heterojunction solar cells

Application of a thin-film SiOx barrier layer prepared by plasma-enhanced chemical vapor deposition (PECVD) enables to achieve, with a Cu-plated amorphous Si/crystalline Si heterojunction (HJ c-Si) solar cell, a retention ratio of over 99% for the maximum power after 6000-h 85°C/85% relative humidity mini-module damp heat (DH) test. A series of DH tests revealed that there existed two crucial factors to maintain long-term photovoltaic properties; protection from moisture ingress from outside of the module and suppression of sodium ions (Na+) diffusion from the module front cover-glass. Surface capping of a HJ c-Si solar cell by a PECVD-SiOx layer reduces the ingress of both moisture and Na+ into the layers below the PECVD-SiOx, leading to an improvement of the reliability after DH test. Besides, the PECVD-SiOx layer plays a role as a barrier layer protecting the heterojunction during the Cu electroplating process. Using a PECVD-SiOx layer, we have developed an industrial metallization scheme for Cu-plated HJ c-Si solar cells. This industrially compatible metallization scheme is effective to increase module conversion efficiency and reduce the metallization cost. Therefore, use of the PECVD-SiOx layer allows the optimization of the HJ c-Si solar cell and contributes to the improvement of the photovoltaic power generation and the reduction of the module production cost.

Surface activation of MnNb2O6 nanosheets by oxalic acid for enhanced photocatalysis

MnNb2O6 nanosheets (P-MNOs) is selectively crystallized by using surface capping ligand with functional sulfonate group (sodium dodecyl benzene sulphonate), which binds to the (131) surface of MnNb2O6 inducing the morphology-controlled crystallization of MnNb2O6 materials. Surface modification of photoactive P-MNOs with electron-rich oxalic acid ligands establishes an excited surface complex layer on phase-pure P-MNO as evidenced by spectroscopic analyses (FT-IR, UV–vis, Raman, PL, etc.), and thus more efficiently photocatalyzes the reduction of Cr(VI) into Cr(III) than solely P-MNOs or oxalic acid under visible light (λ>420nm) via a ligand-to-metal interfacial electron transfer pathway. However, the interaction between oxalic acid and MnNb2O6 is highly dependent upon the morphology of solid MnNb2O6 substrate due to the higher surface-area-to-volume ratio and higher surface activity of (131) planes in the sheet-like morphology. This study could assist the construction of stable niobate material systems to allow a versatile solid surface activation for establishing more energy efficient and robust catalysis process under visible light.

Harnessing Photovoltage: Effects of Film Thickness, TiO2 Nanoparticle Size, MgO and Surface Capping with DSCs.

High photovoltage dye-sensitized solar cells (DSCs) offer an exceptional opportunity to power electrocatalysts for the production of hydrogen from water and the reduction of CO2 to usable fuels with a relatively cost-effective, low-toxicity solar cell. Competitive recombination pathways such as electron transfer from TiO2 films to the redox shuttle or oxidized dye must be minimized to achieve the maximum possible photovoltage (Voc) from DSC devices. A high Voc of 882 mV was achieved with the iodide/triiodide redox shuttle and a ruthenium NCS-ligated dye, HD-2-mono, by utilizing a combined approach of (1) modulating the TiO2 surface area through film thickness and nanoparticle size selection, (2) addition of a MgO insulating layer, and (3) capping available TiO2 film surface sites post film sensitization with an F-SAM (fluorinated self-assembled monolayer) treatment. The exceptional Voc of 882 mV observed is the highest achieved for the popular NCS containing ruthenium sensitizers with >5% PCE and compares favorably to the 769 mV value observed under common device preparation conditions.

Verification of the spar model of a reinforced concrete beam

The paper presents the outcomes of the research aimed at the verification of the computational model simulating a reinforced concrete beam employing spar and 3D finite elements, with account taken of physical nonlinearity. Structural calculations involved in R&D and design effort must factor in non-linear structural behavior both of the material and of structural elements. In particular, this is valid for the analysis of special types of impact (seismic, accidental etc.). However, design models under development may incorporate significantly varying models of nonlinear materials as well as different kinds of finite elements, and both have to be verified. This article considers two models of a hinged (pinned) beam. In the first case, the modeling was based on 3D elements for concrete and on spar elements for reinforcement using Euler-Lagrange coupling of finite elements belonging to concrete and reinforcement (three-dimensional model). The second case the simulation based on spar finite elements (spar model). Both the spar model and 3D model allow for non-linear nature of concrete and reinforcement. In case of concrete the material was set using the Continuous Surface Cap Model, while the reinforcement was modeled involving a bilinear diagram of material behavior.

Comparative analysis of results from experimental and numerical studies on concrete strength

Some results of numerical experiments of testing concrete cubes and prisms on unconfined compression, and the comparison of results obtained with experimental and specified data, are presented in the article. When performing calculations of structures in a nonlinear setting, it is very important to choose adequate deformation diagrams or material models. Because of the fact that there are no instructions how to use the diagrams of concrete and armature deformation in collaboration of steel and concrete, the simulation of reinforced concrete structures by finite elements of the same type without any assumptions is impossible. Numerical experiments have been performed in the LS-DYNA software package. This software package allows simulating the collaboration of concrete and steeling with the help of three-dimensional (for concrete) and rod (for the reinforcement) finite elements. As samples, a cube and a prism with dimensions of 150×150×150 mm and 150×150×600 mm, respectively, have been taken. The samples are simulated by solid finite elements. For the simulation of concrete, the non-linear CSCM (Continuous Surface Cap Model) material is used. The tests were carried out with samples of the following classes of concrete as for cylinder compressive strength: C12, C16, C20, C25, C30, C35. This corresponds to the following classes of cube compression strength: B15, B20, B25, B30, B37, B45. The tests have been carried out considering the friction coefficients between the plates of a testing machine, and a sample. The performed researches have shown that the destruction nature of the samples in a numerical experiment corresponds to the failure nature in real tests. The investigated model of CSCM concrete can be used in the calculation of concrete and reinforced concrete structures with acceptable accuracy for main classes of concrete.

Phosphorous Diffusion in N2+-Implanted Germanium during Flash Lamp Annealing: Influence of Nitrogen on Ge Substrate Damage and Capping Layer Engineering

In this work we present a systematic study on post-implantation phosphorous diffusion control in Ge by co-implanted nitrogen in combination with various surface capping layers (Al2O3, SiO2 and Si3N4). Phosphorous has been implanted at low energy (11 keV) and high dose (1015 cm−2) in p-Ge (100) already implanted or not with low energy (10 keV−5 × 1014 cm−2) N2+. Flash Lamp Annealing (FLA) at 800–850°C for 20 ms in inert ambient has been used as post-implantation annealing scheme. In the absence of nitrogen, significant substrate damage and capping layer deterioration prevents a reliable comparison among the three capping materials. The presence of nitrogen in the Ge substrate, effectively suppresses the damage observed after the FLA. In this case, P diffusion is additionally retarded in the presence of Al2O3 as compared to SiO2 and Si3N4. The experimental results constitute a direct evidence of the action of the three capping layers as sinks for Ge vacancies with different interface recombination velocities. On the contrary, the nitrogen diffusion data suggest that interface recombination velocities of Ge interstitials are almost independent of the capping layer choice.

Origin of polychromatic emission and defect distribution within annealed ZnO nanoparticles

Defects distribution in ZnO nano-particles is introduced by high temperature annealing in air and corresponding visible emission are comprehensively analyzed. Grain size initially increases with increasing annealing temperature until 800°C and decreases after that. Higher temperature annealing alters defect distribution and initiates formation of OZn (Zinc at oxygen site). Formation of OZn, and presence of conventional defects is confirmed by Electron Paramagnetic Resonance spectra. Spatial distribution of polychromatic emission centers in annealed sample is estimated by diffusion mediated growth and confirmed by florescence imaging. Blue emission centre is found to be located on surface of particle/grain which gets modified by surface capping using PEG and PVA. These visible emissions exhibit strong excitation dependence, and can be excited below the bad gap energy. Based on XRD, EPR, emission by low energy excitation, and florescence imaging schematic of defect distribution within particle/grain and their corresponding emission is proposed.

A three-invariant cap-plasticity damage model for cementitious materials

We present a new continuum elastoplastic damage model for cementitious materials which captures their distinct behavior in tension and compression due to crack-induced damage and irreversible plastic deformation. It also describes their response under multi-axial loading with low to high confining pressures. A smooth, closed-convex three stress-invariant yield surface is developed which perpendicularly intersects the negative hydrostatic axis and is composed of a shear loading surface and an elliptical cap. It incorporates a plastic internal state variable (ISV) characterizing non-uniform hardening of both shear loading surface and elliptical cap, while the flow rule is considered to have volumetric non-associativity. Damage evolution laws incorporate two ISVs describing crack growth at the macroscale under tensile and compressive stresses separately. Overall damage under multiaxial loading explicitly considers the effect of confining stresses on damage evolution and stiffness recovery effects under cyclic loading. Model predictions are compared against several experimental results on various concretes and also against responses of recently reported models. The proposed model predicts distinctive features of concrete very well including hardening behavior in triaxial-compression and both pre- and post-peak volumetric behavior.

Modulatory effects of Zn2+ ions on the toxicity of citrate- and PVP-capped gold nanoparticles towards freshwater algae, Scenedesmus obliquus.

Gold nanoparticles (GNPs) are widely used for medical purposes, both in diagnostics as well as drug delivery, and hence are prone to release and distribution in the environment. Thus, we have explored the effects of GNPs with two distinct surface capping (citrate and PVP), and three different sizes (16, 27, and 37nm) at 0.01-, 0.1-, and 1-mgL-1 concentrations on a predominant freshwater alga Scenedesmus obliquus in the sterile freshwater matrix. We have also investigated how an abundant metal ion from freshwater, i.e., Zn2+ ions may modulate the effects of the selected GNPs (40nm, citrate, and PVP capped). Preliminary toxicity results revealed that gold nanoparticles were highly toxic in comparison to zinc ions alone. A significant modulation in the toxicity of Zn ions was not noticed in the presence of GNPs. In contrast, zinc ions minimized the toxicity produced by GNPs (both CIT-37 and PVP-37), despite its individual toxicity. Approximately, about 42, 33, and 25% toxicity reduction was noted at 0.05-, 0.5-, and 5-mgL-1 Zn ions, respectively, for CIT-37 GNPs, while 31% (0.05mgL-1), 24% (0.5mgL-1), and 9% (5mgL-1) of toxicity reduction were noted for PVP-37 GNPs. Maximum toxicity reduction was seen at 0.05mgL-1 of Zn ions. Abbott modeling substantiated antagonistic effects offered by Zn2+ ions on GNPs. Stability and sedimentation data revealed that the addition of zinc ions gradually induced the aggregation of NPs and in turn significantly reduced the toxicity of GNPs. Thus, the naturally existing ions like Zn2+ have an ability to modulate the toxicity of GNPs in a real-world environment scenario.

Aging and behavior of functional TiO2 nanoparticles in aqueous environment

Nanoparticles are usually functionalized with various surface capping moieties in practical applications. Understand the behavior and fate of them is critical to evaluate or even predict their risk to environment. However, little attention has been denoted on this issue until now. Using three commercial TiO2 nanoparticles with different capping moieties, their aging procedures and corresponding change as well as their byproducts were systematically studied. Comprehensive microscopic and spectrometric measurements demonstrated a capping agent-dependent with the aging procedure. All the aging agents exhibited sharp change in morphologies compared to the fresh counterparts. The degraded degree and surface properties including surface charge and hydrophobicity of the functional TiO2 nanoparticles were varied depended on the capping moieties. Furthermore, the behaviors of these byproducts in various background media had also been investigated. Contrastively, environment factors such as pH, electrolyte valence, and humic acid regardless of capping moieties govern the behavior of these byproducts, despite of the capping moieties slightly affect the point of zero charge. This study highlights the influence of the capping moieties and environmental factors to the transformation progress of functional nanomaterials in environment exposure, which contributes to design and assess the environmental risk of other analogous functional nanoparticles in practical application.

Ligand-Mediated Modulation of Layer Thicknesses of Perovskite Methylammonium Lead Bromide Nanoplatelets

Organic metal halide perovskites have rapidly emerged as among the leading candidates for the next generation of photovoltaic and light-emitting devices. The band gap, exciton binding energy, and absorption cross-section of these materials are tunable to some extent by compositional variation. Dimensional confinement represents an attractive alternative to compositional variation for tuning these properties via quantum confinement close to the Bohr radius. While the stabilization of few-layered nanoplatelets of methylammonium lead bromide has recently been demonstrated, mechanistic understanding of synthetic parameters resulting in dimensional confinement remains to be developed. Here we show that the layer thickness can be precisely modulated as a function of the chain length and concentration of the added alkylammonium cations. Surface capping ligands bind preferentially to sheets of corner sharing PbBr6 octahedra and thereby buffer the extent of supersaturation of monomeric units enabling precise modul...

Enhancing 6-APA Productivity and Operational Stability of Penicillin G Acylase via Rapid Surface Capping on Commercial Resins

In this study, immobilized penicillin G acylase (PGA) was prepared via a facile and rapid approach of generating the TA-TiIV layer on PGA-adsorbed commercial resins (PGA@Resins). In brief, the TA-TiIV layer was constructed through coordination-enabled self-assembly of tannic acid (TA) and titanium(IV) bis(ammonium lactate) dihydroxide (Ti-BALDH). In comparison to PGA@Resins, TA-TiIV-capped PGA@Resins exhibited higher 6-aminopenicillanic acid (6-APA) productivity and enhanced operational stability along with comparable activity recovery during the catalytic hydrolysis of penicillin G potassium (PGK). Particularly, TA-TiIV-capped PGA@Resins exhibited relative activities of 103.7% and 81.51%, respectively, after 68-day storage and 20 cycles, indicating significantly enhanced storage and recycling stabilities compared to PGA@Resins (68.98% and 62.88%). Both immobilized PGA were further packed into a glass column for hydrolyzing PGK in a continuous flow reactor, where TA-TiIV-capped PGA@Resins displayed a much...

Photoinduced Electron-Transfer Quenching of Luminescent Silicon Nanocrystals as a Way To Estimate the Position of the Conduction and Valence Bands by Marcus Theory

Photoluminescence of silicon nanocrystals (SiNCs) in the presence of a series of quinone electron acceptors and ferrocene electron donors is quenched by oxidative and reductive electron transfer dynamic processes, respectively. The rate of these processes is investigated as a function of (a) the thermodynamic driving force of the reaction, by changing the reduction potentials of the acceptor or donor molecules, (b) the dimension of SiNCs (diameter = 3.2 or 5.0 nm), (c) the surface capping layer on SiNCs (dodecyl or ethylbenzene groups), and (d) the solvent polarity (toluene vs dichloromethane). The results were interpreted within the classical Marcus theory, enabling us to estimate the position of the valence and conduction bands, as well as the reorganization energy (particularly small, as expected for quantum dots) and electronic transmission coefficients. The last parameter is in the range 10–5–10–6, demonstrating the nonadiabaticity of the process, and it decreases upon increasing the SiNC dimensions: this result is in line with a larger number of excitons generated in the inner silicon core for larger SiNCs and thus resulting in a lower electronic coupling with the quencher molecules.

Influence of Capping Ligand and Synthesis Method on Structure and Morphology of Aqueous Phase Synthesized CuInSe2 Nanoparticles

A facile route to synthesize copper indium diselenide (CuInSe2) nanoparticles in aqueous medium was developed using mercaptoacetic acid (MAA) as capping agent. Two different mole ratios (5 and 10) of MAA were used to synthesize CuInSe2 nanoparticles at room temperature, as well as hydrothermal (high temperature) method. Powder x-ray diffraction analysis reveals that the nanoparticles exhibit chalcopyrite phase and the crystallinity increases with increasing the capping ratio. Raman analysis shows a strong band at 233 cm−1 due to the combination of B2 (E) modes. Broad absorption spectra were observed for the synthesized CuInSe2 nanoparticles. The effective surface capping by MAA on the nanoparticles surface was confirmed through attenuated total reflection–Fourier transform infrared spectral analysis. The thermal stability of the synthesized samples was analyzed through thermogravimetric analysis–differential scanning calorimetry. The change in morphology of the synthesized samples was analyzed through scanning electron microscope and it shows that the samples prepared at room temperature are spherical in shape, whereas hydrothermally synthesized samples were found to have nanorod- and nanoflake-like structures. Transmission electron microscope analysis further indicates larger grains for the hydrothermally prepared samples with 10 mol ratio of MAA. Comparative analyses were made for synthesizing CuInSe2 nanoparticles by two different methods to explore the role of ligand and influence of temperature.

Enhancement of Thermal Stability of Sputtered Nanoporous Pt Thin Film Using Oxygen Plasma Treatment in Low Temperature Solid Oxide Fuel Cells

Sputtered nanoporous platinum (Pt) thin films are common choices as catalytic cathodes for low temperature (300~500°C) solid oxide fuel cells (LT-SOFCs) for its high catalytic activity towards oxygen reduction reaction. However, the nanoporous pure Pt is vulnerable to thermal coagulation during high temperature operation, which often causes irreversible deterioration to the cell performance. In our earlier work, physical confinement of the nanoporous Pt with a few nanometers of zirconia (ZrO2) conformal coating by atomic layer deposition (ALD) improved the thermal stability of Pt significantly, with more than 50% of the cell power density retained after 80 hours of operation. Still, around 29.5% of cell power density degradation was observed in cells using ALD-ZrO2 capped nanoporous Pt cathode. It is likely that the poor adhesion between the Pt cathode and the yttria-stabilized zirconia (YSZ) electrolyte that caused the triple phase boundaries to be unstable under high temperature operation and therefore a significant thermal degradation is still observed. In this work, we studied the effect of adhesion between Pt and YSZ on the morphological stability of nanoporous Pt at the Pt/YSZ interface. The surface of YSZ electrolyte was treated with oxygen plasma to modify the wettability between ALD-ZrO2 capped Pt and YSZ. The contact angle of a water droplet on the untreated YSZ surface was 80˚, while it dropped to 16˚ on the oxygen-plasma treated YSZ surface, meaning a more hydrophilic YSZ surface was obtained. The oxygen-based functional groups may have formed after the oxygen plasma treatment and increased the YSZ-water interfacial energy. The additional chemical bonding may exist if the nanoporous Pt films are deposited on surface-treated YSZ to stabilize the morphology of nanoporous Pt at the Pt/YSZ interface. The surface confined nanoporous Pt thin film cathodes were annealed at 600°C to induce the agglomeration, followed by delamination of the Pt cathode film from the YSZ substrate using double cantilever beam (DCB), in order to investigate the morphological stability of the nanoporous Pt at the Pt/YSZ interface after oxygen plasma treatment. The interfacial morphology observation showed that the Pt agglomeration at the Pt/YSZ interface remained significantly severe for Pt cathode with only ALD-ZrO2 surface capping. For Pt cathode deposited on YSZ substrate treated with 5 minutes of oxygen plasma at 18 watts showed improved interfacial thermal stability. A fuel cell with ALD-ZrO2 capped nanoporous Pt cathode thin film deposited on the oxygen-plasma treated YSZ electrolyte was tested. It was observed that the performance degradation was effectively hindered by the oxygen plasma treatment after 75 hours of operation at 450°C. Figure 1

Understanding the Role of Surface Capping Ligands in Passivating the Quantum Dots Using Copper Dopants as Internal Sensor

The role of ligands in passivating quantum dots has been studied in this work using Cu doping as internal sensors. This has been elucidated using the example of dodecanethiol, 3-mercaptopropionic acid, trioctylphosphine, trioctylphosphine oxide, and primary amines for the passivation of CdSe quantum dots by exchanging the original ligands. Steady state and time dependent photoluminescence spectra of the Cu emission have provided the basis for determining the role of ligands. The surface of the quantum dots with ligand exchange has been monitored using nuclear magnetic resonance spectroscopy. The results suggest that the presence of trioctylphosphine, trioctylphosphine oxide, and oleylamine ligands on CdSe quantum dot surface lead to better photoluminescence efficiency. Further, increase in the chain length of the primary amines increases the effectiveness of passivation on the CdSe quantum dot surface. We have also extended this method to the study of oleylamine capping in CdS quantum dots.

Biocompatible Glutathione Capped Functionalized Carbon Dots as Nanosensors for the Detection of Silver Nanoparticles in Aqueous Solution and Human Cells as well as Bacterial Cells

AbstractFunctional carbon materials have aroused much attention owing to their applications in cellular imaging and sensing. In this paper, we use a hydrothermal approach to prepare luminescent sodium citrate carbon dots (CDs) using glutathione (GSH) as the surface capping reagent. The effects of feed ratio, reaction temperature and reaction time on the luminescent behavior of CDs are investigated. Subsequently, as‐prepared CDs are characterized by UV‐vis, photoluminescence, X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). The luminescent CDs exhibit good stability in the presence of various ions or photo irradiation. Furthermore, the luminescence of the CDs is reversible upon the pH cycling between pH=4 and 6. In addition, the emission intensity of CDs decreases gradually with increasing the concentration of silver nanoparticles (AgNPs) and a linear relationship between the logarithm of emission intensity and the concentration of AgNPs is observed within the investigated concentration ranging from 0 to 40 μmol•L−1. The detection limit is 0.9 μmol•L−1 in terms of signal‐to‐noise ratio of 3. More importantly, the sensor can be successfully applied to the detection of AgNPs in real lake water, urine of human, Hep‐2 cells, E. Coli and Salmonella bacteria, which offers a promising platform for environmental and biological sensing applications.

Effect of phosphate and oleic acid capping on structure, magnetic properties and thermal stability of iron oxide nanoparticles

The thermal stability and magnetic properties of iron oxide nanomaterials under different environmental conditions are important for technological applications. Herein, we report the influence of dynamic capping of iron oxide nanoparticles with phosphate and oleic acid, on their structure, magnetic properties and thermal stability and compare the results with that of uncoated nanoparticles. The composition, structure, morphology, quality of capping, thermal stability and magnetic properties of prepared magnetite nanoparticles are evaluated by using X-Ray Diffractometer (XRD), Small angle X-ray scattering (SAXS), High resolution transmission electron microscopy (HRTEM), Energy dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR) spectrometer, Thermo gravimetric analyzer (TGA), Differential scanning calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). Our results suggest that the rapid adsorption of phosphate ions onto specific crystal planes of nucleated magnetite enabled the growth of magnetite core into nearly cubic shape while the oleic acid capping enabled a homogeneous growth of magnetite core along all the crystallographic directions, enabling the formation of nearly spherical particles with narrow size distribution. On the contrary, the phosphate adsorbs as multilayer islands on nanoparticles, leading to a broader size distribution, identical to the uncoated particles. The HRTEM analysis showed dark areas with asymmetric contrast in uncoated nanoparticles, which was not observed in phosphate and oleic acid capped magnetite. The FTIR study on phosphate coated magnetite particles confirms that the surface capping is a mixture of mono and non-protonated monodentate phosphate complexes. The DSC studies confirm a 100 °C enhancement in the magnetic phase thermal stability in phosphate-coated particles, as compared to uncoated and oleic acid coated magnetite. The temperature dependant magnetization results showed a lower blocking temperature for phosphate capped nanoparticles due to the denser multilayer islands of phosphate over magnetite as compared to a uniform close packed monolayer coverage of oleic acid. These results are useful for tailoring stable superparamagnetic nanoparticles for technological applications.

Pulsed current electrodeposition parameters to control the Sn particle size to enhance electrochemical performance as anode material in lithium ion batteries

Abstract The Sn nanoparticles were synthesized through pulsed current electrodeposition in an acidic electrochemical bath containing polyvinylpyrrolidone (PVP) in order to control the electrodeposition rate of Sn reduction on copper collector electrode. The anode prepared at electrochemical bath containing PVP concentration of about 10 g·L−1 showed highest discharge capacity and cycleability as two main criteria in lithium ion batteries. Also, the pulsed current characteristics such as frequency and current density were investigated and 10 Hz and 20 mA·cm− 2, respectively, are obtained as the optimum parameters. The synthesis of Sn nanoparticles in such media was successfully developed. The sizes and morphologies of NPs were characterized by X-ray diffraction and scanning electron microscopy. Our findings indicated that the nanosized spherical particles with a diameter ranging from 80 to 100 nm could be formed at optimum concentration. The discharge capacity of synthesized Sn nanoparticles was obtained about 1350 mAh g− 1, indicating a 32% increase compared to the synthesized Sn particles with constant current electrodeposition method. Additionally, the discharge capacity of around 550 mAh g–1 is obtained in the 50th cycle, which shows an appropriate cycleability compared to the Sn film electrode prepared by a constant current electrodeposition. The discharge capacities obtained indicated a considerable improvement compared to similar works. The particles size of coated Sn on collector electrode is resulted from interplay between the rate of nucleation and growing rate of particles. PVP affects the kinetic of electrodeposition through surface capping and complexing of Sn2 + species.

Synthesis and catalytic activity of the metastable phase of gold phosphide

Recently, transition metal phosphides have found new applications as catalysts for the hydrogen evolution reaction that has generated an impetus to synthesize these materials at the nanoscale. In this work, Au2P3 was synthesized utilizing the high temperature decomposition of tri-n-octylphosphine as a source of elemental phosphorous. Gold nanorods were used as morphological templates with the aim of controlling the shape and size of the resulting gold phosphide particles. We demonstrate that the surface capping ligand of the gold nanoparticle precursors can influence the purity and extent to which the gold phosphide phase will form. Gold nanorods functionalized with 1-dodecanethiol undergo digestive ripening to produce discrete spherical particles that exhibit reduced reactivity towards phosphorous, resulting in low yields of the gold phosphide. In contrast, gold phosphide was obtained as a phase pure product when cetyltrimethylammonium bromide functionalized gold nanorods are used instead. The Au2P3 nanoparticles exhibited higher activity than polycrystalline gold towards the hydrogen evolution reaction.