Effect of swift heavy ion irradiation on the physical properties of CuIn(S0.4Se0.6)2 alloy thin films prepared by solution growth technique

Alloy thin films of CuIn(S_0.4Se_0.6)₂ material were deposited using the solution growth technique. The various deposition parameters such as pH of solution, time, concentration of ions and temperature have been optimized for the device grade thin films. The as-deposited films were annealed in a rapid thermal annealing (RTA) system at 450 °C in air for 5 min and subjected to high-energy Ag ion irradiations. Ag ion irradiation has been performed with an energy of 100 MeV at a fluency of 5×10¹² ions/cm² on the thin film. The changes in optical and electrical properties that occurred before and after post-deposition treatments in CuIn(S_0.4Se_0.6)₂ thin films were studied using X-ray diffraction (XRD) and AFM; increase in crystallinity was observed after annealing and irradiation. In addition, structural damages were observed in irradiated thin films. After annealing and irradiation, the surface roughness was seen to be increased. Decrease in resistivity was observed, which is consistent with the optical energy band gap. The results are explained by considering the high energy deposited due to the electronic energy loss upon irradiation, which modified the properties of the material.     

Parallel detection,quantification, and depth profiling of peptides with dynamic-secondary ion mass spectrometry (D-SIMS) ionized by C60–Ar co-sputtering

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) using pulsed C₆₀⁺ primary ions is a promising technique for analyzing biological specimens with high surface sensitivities. With molecular secondary ions of high masses, multiple molecules can be identified simultaneously without prior separation or isotope labeling. Previous reports using the C₆₀⁺ primary ion have been based on static-SIMS, which makes depth profiling complicated. Therefore, a dynamic-SIMS technique is reported here. Mixed peptides in the cryoprotectant trehalose were used as a model for evaluating the parameters that lead to the parallel detection and quantification of biomaterials. Trehalose was mixed separately with different concentrations of peptides. The peptide secondary ion intensities (normalized with respect to those of trehalose) were directly proportional to their concentration in the matrix (0.01–2.5 mol%). Quantification curves for each peptide were generated by plotting the percentage of peptides in trehalose versus the normalized SIMS intensities. Using these curves, the parallel detection, identification, and quantification of multiple peptides was achieved. Low energy Ar⁺ was used to co-sputter and ionize the peptide-doped trehalose sample to suppress the carbon deposition associated with C₆₀⁺ bombardment, which suppressed the ion intensities during the depth profiling. This co-sputtering technique yielded steadier molecular ion intensities than when using a single C₆₀⁺ beam. In other words, co-sputtering is suitable for the depth profiling of thick specimens. In addition, the smoother surface generated by co-sputtering yielded greater depth resolution than C₆₀⁺ sputtering. Furthermore, because C₆₀⁺ is responsible for generating the molecular ions, the dosage of the auxiliary Ar⁺ does not significantly affect the quantification curves.     

Improve the physical and chemical properties of biocompatible polymer material by MeV He ion beam

There is a high interest in improving the hydrophilicity of polymer surfaces due to their wide use for technological purposes. In this study Ultra High Molecular Weight Polyethylene (UHMWPE) as a biocompatible material was bombarded with 1 MeV He ions to the fluences ranging from 1×10¹³ to 5×10¹⁴ cm^?2. The pristine and ion beam modified samples were investigated by photoluminescence (PL), ultraviolet–visible (UV–vis) spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The changes of wettability and surface free energy were determined by the contact angle measurements. The obtained results showed that the ion bombardment induced decrease in integrated luminescence intensity and decrease in the transmittance with increase of ion fluence as well. This is might be attributed to degradation of polymer surface and/or creation of new electronic levels in the forbidden gap. The FTIR spectral studies indicate that the ion beam induces chemical modifications within the bombarded UHMWPE. Formation of carbonyl groups (C=O) on the polymer surface was studied. Direct relationship of the wettability and surface free energy of the bombarded polymer with the ion fluences was observed.     

A high performance solid-state asymmetric supercapacitor based on Anderson-type polyoxometalate-doped graphene aerogel

The manufacture of single-atom transition metal-doping carbon nanocomposites as electrode materials is crucial for electrochemical energy storage with high energy and power density. However, the simple strategy for preparation of such active materials with controlled structure remains a great challenge. Here, cobalt-doped carbon nanocomposites (Co-POM/rGO) were synthesized successfully by deposition of Anderson-type polyoxometalate (POM) on the surface of reduced graphene oxide (rGO) aerogel via one-pot hydrothermal treatment. The resulting Co-POM/rGO possesses three-dimensional graphene-based frameworks with hierarchical porous structure, high surface area and uniform single-atom metal doping. These intriguing features render Co-POM/rGO to be a promising electrode for applications in electrochemical energy storage. As an electrode material of a supercapacitor, Co-POM/rGO shows high-performance electrochemical energy storage (211.3 F g^?1 at 0.5 A g^?1). Furthermore, the solid-state asymmetric supercapacitor (ASC) device, using Co-POM/rGO as a positive electrode, exhibits the outstanding energy density of 37.6 Wh kg^?1 at a power density of 500 W kg^?1, and high capacitance retention of 95.2% after 5000 charge–discharge cycles. These results indicate that the proposed strategy for rational design of single-atom-metal doped carbon nanocomposites for flexible ASC devices with excellent capacitive properties.

     

Deposition of U(VI) at polypyrrole film electrodes modified with chlorophosphon azoIII

A modified Gr/ppy, chlorophosphon azoIII electrode was produced by the electrochemical polymerization of pyrrole and utilized for the deposition of uranyl ions. The polymerization rate of 1.43×10⁻¹ s⁻¹ was observed with the use of NBR, a precoating agent, which was 1.3 times faster than that without NBR. The amount of deposited uranyl ions determined by QCM was 1.12×10¹⁸ molecule cm⁻² when the polymerized ppy was 1.70 C cm⁻². The value for deposited uranyl ion was 2.68 times larger than that determined by the area of oxidation wave in CV, meaning that QCM might be the method of the choice for the investigation of uranyl ion deposition of a polymer modified electrode. The impedance of the ppy modified electrode increased with the consecutive modification of Gr/ppy,AzoIII,UO⁺ and the resistance for the electron transfer was 1.32 kΩ for the ppy-only electrode, 9.43 kΩ for AsoIII modification, and 11.82 kΩ for the deposition of the uranyl ion. The conductive process for Gr/ppy was diffusion controlled, however, for Gr/ppy,azoIII,UO⁺, it was thought to be the combination of ion doping process (low frequency region) and the electron transfer of the ppy film (high frequency region).     

Ion‐beam‐induced morphology on the surface of thin polymer films at low current density and high ion fluence

The effect of Xe⁺ bombardment on the surface morphology of four different polymers, polystyrene (PS), poly(phenylene oxide), polyisobutylene, and polydimethylsiloxane, was investigated in ion energy and fluence ranges of interest for secondary ion mass spectrometry depth‐profiling analysis. Atomic force microscopy (AFM) was applied to analyze the surface topography of pristine and irradiated polymers. AFM analyses of nonirradiated polymer films showed a feature‐free surface with different smoothness. We studied the influence of different Xe⁺ beam parameters, including the incidence angle, ion energy (660–4000 eV), current density (0.5 × 10² to 8.7 × 10² nA/cm²), and ion fluence (4 × 10¹⁴ to 2 × 10¹⁷ ion/cm²). Xe⁺ bombardment of PS with 3–4 keV at a high current density did not induce any change in the surface morphology. Similarly, for ion irradiation with lower energy, no surface morphology change was found with a current density higher than 2.6 × 10² nA/cm² and an ion fluence up to 4 × 10¹⁶ ion/cm². However, Xe⁺ irradiation with a lower current density and a higher ion fluence led to topography development for all of the polymers. The roughness of the polymer surface increased, and well‐defined patterns appeared. The surface roughness increased with ion irradiation fluence and with the decrease of the current density. A pattern orientation along the beam direction was visible for inclined incidence between 15° and 45° with respect to the surface normal. Orientation was not seen at normal incidence. The surface topography development could be explained on the basis of the balance between surface damage and sputtering induced by the primary ion beam and redeposition–adsorption from the gas phase. Time‐of‐flight secondary ion mass spectrometry analyses of irradiated PS showed strong surface modifications of the molecular structure and the presence of new material. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 314–325, 2001     

Studies of GaAs surface roughness and organic masks resistance depending on the ion-beam energy

Summary The development of A^III–B^V semiconductor surfaces exposed to ion-beam irradiation in the ion energy range from 100 to 1000 eV and the ion current density of 1 mA/cm² (max) is investigated. The ion-beam etching with an ion energy of 1 keV results in sharp cones and needles on the semiconductor surface due to the surface contamination and unevenness. Etching with ion-beam energies in the order of 300 eV and with etch rates higher than 1000 /min produces relatively even GaAs surfaces. In case of reactive gases (i.e. CCl₂F₂ and the mixture of CCl₂F₂+Ar) ion-beam etching results in significantly higher etch rates; however, the mask residue contains Cl and F. In studies on the ion-beam resistance of organic masks selectivities as high as 13:1 for the photoresist CM-79 with an ion energy of 180 eV and an ion current density of approximately 0.3 mA/cm² were achieved.     

Synthesis of nanostructured electrocatalysts based on magnetron ion sputtering

Nanostructured platinum catalysts for electrochemical systems with proton-exchange membranes (PEMs) have been synthesized by magnetron ion sputtering on a carbon support. The design of the powder support stirrer has been optimized to ensure uniform surface coverage with platinum metal nanoparticles. The deposition parameters (discharge power, deposition time, and bias voltage) that make it possible to obtain electrocatalysts with a large specific surface area (up to 44 m²/g) have been determined. The resulting catalysts have been studied by transmission electron microscopy and X-ray diffraction. The samples with platinum particles 3 to 4 nm in size uniformly distributed over the carbon surface and forming a single phase exhibit the greatest efficiency. The electrodes based on the synthesized electrocatalysts have been tested in a liquid electrolyte and as a component of a fuel cell and PEM water electrolyzer. The voltage across the fuel cell with the synthesized Pt/C electrocatalyst (44 m²/g) at a current density of 1 A/cm² is as high as 0.55 V, which corresponds to a specific power of 550 mW/cm². Qualitative correlations between the parameters of the synthesized catalysts and the deposition conditions have been established.     

Chemical structure and surface morphology evolution of glow discharge polymer films by Ar‐ions intermittent etching

The Ar‐ions intermittent‐etching technique was successfully incorporated during the deposition of glow discharge polymer (GDP) films. The ionic components and ion energy distributions (IEDs) of C₄H₈/H₂ and C₄H₈/H₂/Ar plasma were diagnosed by an energy‐resolved mass spectrometer, respectively. The Fourier transform infrared spectroscopy, scanning electron microscope, and white‐light interferometer were used to studying the chemical structure, surface morphology, and roughness of the GDP films, which are deposited with the various time of Ar‐ions intermittent etching. With the introduction of Ar into the chamber, the intensity of the C H absorption peaks becomes weak and the large‐mass C H species were ionized and dissociated from the mass spectrometer results. The surface roughness of GDP films are decreased with Ar‐ions intermittent etching, the lowest surface roughness (Rq) is only 33.6 nm when the intermittent cycle is 60 minutes/15 minutes. The highest sp³CH₃ (sym) absorption peaks are attributed to samples also with 60‐minute/15‐minute intermittent cycle, which shortens the length of the carbon chain and reduces the probability of the cluster formations.     

Sensitive and Green Method for Determination of Chemical Oxygen Demand Using a Nano‐copper Based Electrochemical Sensor

Copper nanoparticles (nano‐Cu) were electrodeposited on the surface of glassy carbon electrode (GCE) potentiostatically at −0.6 V vs. Ag/AgCl for 60 s. The developed nano‐copper modified glassy carbon electrode (nano‐Cu/GCE) was optimized and utilized for electrochemical assay of chemical oxygen demand (COD) using glycine as a standard. The surface morphology and chemical composition of nano‐Cu/GCE were investigated using scanning electron microscope (SEM) and energy dispersive X‐ray spectrometer (EDX), respectively. The electrochemical behavior was investigated using linear sweep voltammetry (LSV) which is characterized by a remarkable anodic peak at ∼0.6 V, compared to bare GCE. This indicates that nano‐Cu enhances significantly the electrochemical oxidation of glycine. The effect of different deposition parameters, such as Cu²⁺ concentration, deposition potential, deposition time, pH, and scan rate on the response of the developed sensor were investigated. The optimized nano‐Cu/GCE based COD sensor exhibited a linear range of 15 to 629.3 ppm, and a lower limit of detection (LOD) of 1.7 ppm (S/N=3). This developed method exhibited high tolerance level to chloride ion (0.35 M chloride ion has minimal influence). The analytical utility of the prepared COD sensor was demonstrated by investigating the COD recovery (99.8±4.3) and the assay of COD in different water samples. The results obtained were verified using the standard dichromate method.     

ToF-secondary ion mass-spectrometric study of copper deposition and stripping on directly heated screen-printed gold electrodes

We report about a new kind of directly heated gold electrode. All electrodes including a directly heated gold loop electrode, a Ag pseudo reference, and a carbon counter electrode have been screen-printed on a ceramic alumina substrate. Thermal behaviour was studied by potentiometry using either an external or the integrated reference electrode. Stripping voltammetric copper signals were greatly improved at elevated deposition temperature. Secondary ion mass spectrometric studies (ToF-SIMS) revealed that different negative ionic species of copper complexes can be found on the gold electrode surface as a result of ion bombardment during SIMS analysis like Cu^?, CuCl^? and CuCl₂ ^?. SIMS surface imaging using a fine focussed ion beam over the surface allowed us to obtain ion images (chemical maps) of the analyzed sample. SIMS depth profile analysis of the gold loop electrode was performed after copper deposition at room temperature (23 °C) and at 60 °C. CuCl₂ ^? ion was used for the depth profile studies as it has shown the highest intensity among other observed species. Surface spectroscopic analysis, surface imaging and depth profile analysis have shown that the amount of deposited copper species on the gold loop electrode was increased upon increasing electrode temperature during the deposition step. Therefore, the presence of chloride in the solution will hinder underpotential deposition of Cu(0) and lead to badly defined and resolved stripping peaks.     

Experimental and theoretical determination of the mixing efficiency at low‐energy Ar+ bombardment: case study of the Cu/Co system

The mixing of a Co/Cu bilayer induced by low‐energy ion bombardment was studied by AES depth profiling and molecular dynamic (MD) simulation. The conditions of the ion bombardment were as follows: Ar⁺ ion, 1 keV energy, 82° angle of incidence (with respect to the surface normal). In AES depth profiling, the in‐depth concentration distribution was estimated from the measured Auger intensities assuming that the in‐depth distribution is an erf function. The variance (σ²) of the erf function gave the broadening of the interface due to ion bombardment, which divided by the fluence (Φ) and deposited energy (F_D given by SRIM) gave the mixing efficiency (σ²/ΦF_D) to be 0.08 ± 0.01 nm⁵/keV. The mixing efficiency calculated by MD, 0.09 nm⁵/keV, agreed well with that estimated from the experimental data, and both have been close to the value assuming ballistic mixing. Copyright © 2007 John Wiley & Sons, Ltd.     

Nickel foam-supported porous NiO/polyaniline film as anode for lithium ion batteries

Nickel foam-supported porous NiO film was prepared by a chemical bath deposition technique, and the NiO/polyaniline (PANI) film was obtained by depositing the PANI layer on the surface of the NiO film. The NiO film was constructed by NiO nanoflakes, and after the deposition of PANI, these nanoflakes were coated by PANI. As an anode for lithium ion batteries, the NiO/PANI film exhibits weaker polarization as compared to the NiO film. The specific capacity after 50 cycles for NiO/PANI film is 520 mAh g⁻¹ at 1 C, higher than that of NiO film (440 mAh g⁻¹). The improvement of these properties is attributed to the enhanced electrical conduction and film stability of the electrode with PANI.     

Amorphous cobalt silicate nanobelts@carbon composites as a stable anode material for lithium ion batteries

During the past decade, tremendous attention has been given to the development of new electrode materials with high capacity to meet the requirements of electrode materials with high energy density in lithium ion batteries. Very recently, cobalt silicate has been proposed as a new type of high capacity anode material for lithium ion batteries. However, the bulky cobalt silicate demonstrates limited electrochemical performance. Nanostructure engineering and carbon coating represent two promising strategies to improve the electrochemical performance of electrode materials. Herein, we developed a template method for the synthesis of amorphous cobalt silicate nanobelts which can be coated with carbon through the deposition and thermal decomposition of phenol formaldehyde resin. Tested as an anode material, the amorphous cobalt silicate nanobelts@carbon composites exhibit a reversible high capacity of 745 mA h g^–1 at a current density of 100 mA g^–1, and a long life span of up to 1000 cycles with a stable capacity retention of 480 mA h g^–1 at a current density of 500 mA g^–1. The outstanding electrochemical performance of the composites indicates their high potential as an anode material for lithium ion batteries. The results here are expected to stimulate further research into transition metal silicate nanostructures for lithium ion battery applications.     

Measuring internal energy deposition in collisional activation using hydrated ion nanocalorimetry to obtain peptide dissociation energies and entropies

The internal energy deposited in both on- and off-resonance collisional activation in Fourier transform ion cyclotron resonance mass spectrometry is measured with ion nanocalorimetry and is used to obtain information about the dissociation energy and entropy of a protonated peptide. Activation of Na⁺(H₂O)₃₀ results in sequential loss of water molecules, and the internal energy of the activated ion can be obtained from the abundances of the product ions. Information about internal energy deposition in on-resonance collisional activation of protonated peptides is inferred from dissociation data obtained under identical conditions for hydrated ions that have similar m/z and degrees-of-freedom. From experimental internal energy deposition curves and Rice-Ramsperger-Kassel-Marcus (RRKM) theory, dissociation data as a function of collision energy for protonated leucine enkephalin, which has a comparable m/z and degrees-of-freedom as Na⁺(H₂O)₃₀, are modeled. The threshold dissociation energies and entropies are correlated for data acquired at a single time point, resulting in a relatively wide range of threshold dissociation energies (1.1 to 1.7 eV) that can fit these data. However, this range of values could be significantly reduced by fitting data acquired at different dissociation times. By measuring the internal energy of an activated ion, the number of fitting parameters necessary to obtain information about the dissociation parameters by modeling these data is reduced and could result in improved accuracy for such methods.     

Radiation damage in dielectric and semiconductor single crystals (direct observation)

The surfaces of boron-doped synthetic and natural diamonds have been investigated by using the scanning tunnelling microscope (STM) and the scanning electronic microscope (SEM) before and after irradiating the samples with ⁴⁰Ar (25 MeV), ⁸⁴Kr (210 MeV) and ¹²⁵Xe (124 MeV) ions. The structures observed after irradiation showed craters with diameters ranging from 3 nm up to 20 nm, which could be interpreted as single ion tracks and multiple hits of ions at the nearest positions of the surface. In the case of argon ion irradiation, the surface was found to be completely amorphous, but after xenon irradiation one could see parts of surface without amorphism. This can be explained by the influence of high inelastic energy losses. The energy and temperature criteria of crater formation as a result of heavy ion irradiation are introduced.     

Surface engineering towards high-energy carbon cathode for advanced aqueous zinc-ion hybrid capacitors

Opportunities coexist with challenges for the development of carbon-based cathodes with a high energy density applied for zinc ion hybrid capacitors (ZIHCs). In the present study, a facile and effective surface engineering approach is demonstrated to greatly improve the energy storage ability of commercial carbon paper (CP) in ZIHC. Benefiting from the introduced oxygen functional groups, larger surface area and improved surface wettability upon air calcination, the assembled aqueous ZIHC with the functionalized carbon paper (FCP) exhibits a much higher areal capacity of 0.22 mAh/cm² at 1 mA/cm², outperforming the counterpart with blank CP by over 5000 times. More importantly, a superior energy density and power density of 130.8 µWh/cm² and 7460.5 µW/cm², are respectively delivered. Furthermore, more than 90% of the initial capacity is retained over 10000 cycles. This surface engineering strategy to improve the energy storage capability is potentially applicable to developing a wide range of high-energy carbon electrode materials.     

Preparation of a palladium alloy composite membrane supported in a porous stainless steel by vacuum electrodeposition

Pinhole-free palladium/nickel (Pd/Ni) alloy membranes deposited on a porous stainless steel (SUS) support have been fabricated. The deposition was made by vacuum electrodeposition technique which could produce the alloy film less than 1 μm thick. This technique allows for the Pd/Ni alloy by employing Pd/Ni complex reagent, and typical Pd/Ni plating had compositions of 78% Pd and 22% Ni. In order to make the surface smooth and enhance the adhesive bond between the top layer and the substrate, a nascent porous SUS disk was treated sequently with submicron nickel powder and CuCN solution. The important parameters that can affect deposition were pore size, defects, and surface roughness of substrate. The membranes were characterized by permeation experiments with hydrogen and nitrogen at temperatures ranging from 623 to 823 K and pressures from 10.3 to 51.7 cmHg. The composite membranes prepared in this technique yielded excellent separation performance for hydrogen: hydrogen permeance of 5.79×10⁻² cm³/cm² cmHg s and hydrogen/nitrogen (H₂/N₂) selectivity was 4700 at 823 K.     

Optimisation of mercury film deposition on glassy carbon electrodes: evaluation of the combined effects of pH, thiocyanate ion and deposition potential

The combined effects of pH, thiocyanate ion and deposition potential in the characteristics of thin mercury film electrodes plated on glassy carbon surfaces are evaluated. Charges of deposited mercury are used as an experimental parameter for the estimation of the effectiveness of the mercury deposition procedure. The sensitivity of the anodic stripping voltammetry (ASV) method for the determination of lead at in situ and at ex situ formed thin mercury films are also examined. It was concluded that, in acidic solutions (pH 2.5-5.7) and fairly negative deposition potentials, e.g. −1.3 to −1.5 V, thiocyanate ion promotes the formation of the mercury film, in respect both to the amount of deposited mercury and to the mercury deposition rate. Also, the mercury coatings produced in thiocyanate solutions are more homogeneous, as depicted by microscopic examinations. In the presence of thiocyanate there is no obvious advantage of using high concentrations of mercury and/or high deposition times for the in situ and ex situ preparation of the mercury film electrodes. The optimised thin mercury film electrode ex situ prepared in a 5.0 mM thiocyanate solution of pH 3.4 was successfully applied to the ASV determination of lead and copper in acidified seawater (pH 2). The limit of detection (3σ) was 6×10⁻¹¹ M for lead and 2×10⁻¹⁰ M for copper for a deposition time of 5 min. Relative standard deviations (R.S.D.s) of <1.2% were obtained for determinations at the nanomolar of concentration level.     

Hofmeister effects at low salt concentration due to surface charge transfer

We present a theoretical comparison of the surface forces between two graphite-like surfaces at salt concentrations below 10 mM with surfaces charged by various mechanisms. Surface forces include a surface charging or chemisorption contribution to the total free energy. Surfaces are charged by charge regulation (H⁺ binding), site competition (H⁺ and cation binding) and redox charging with electrodes coupled to a countercell. Constant surface charge is also considered. Surface parameters are calibrated to give the same potential when isolated. Nonelectrostatic physisorption energies of the potential determining ions provide a specific and significant contribution to the charging energy. Consequently ion specificity is found in the surface forces at concentrations of 1–10 mM, which is not observed under constant charge conditions. The force between redox electrodes continues to show Hofmeister effects at 0.01 mM. We refer to this low concentration Hofmeister effect as “Hofmeister charging”, and suggest that the more common high concentration ion specific effects may be known as “Hofmeister screening”. Hofmeister series are considered over LiCl, NaCl, KCl and NaNO₃, NaClO₄, NaSCN with the cations (or H⁺) being the potential determining ions. A K⁺ anomaly is attributed to the small size of the weakly hydrated chaotropic K⁺ ion, with Li⁺ and Na⁺ explicitly modelled as strongly hydrated cosmotropes.