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Here we investigate the oxygen reduction reaction electrocatalytic activity and the corrosion stability of several ternary Pt–Au–Co and Pt–Ir–Co alloys, with Pt–Au–Co having never been previously studied for ORR. The addition of Au fine tunes the lattice parameter and the surface electronic structure to enable activity and cycling stability that is unachievable in Pt–25 atom % Co (state-of-the-art binary baseline). The ternary alloys exhibit a volcano-type dependence of catalytic efficacy on the content of Au or Ir. Pt–2.5 atom % Au–25 atom % Co alloy shows a specific activity of 1.41 mA cm–2 at 0.95 V, which is 16% and 404% higher than those of identically synthesized Pt–Co and pure Pt, respectively. This enhancement is promising in comparison to a range of previously published Pt “skeleton” and Pt “skin” alloys and is in fact the most optimum reported for a skeleton-type system. The catalysts exhibit dramatically improved corrosion stability with increasing levels of Au or Ir substitution, with the spec...

A key advancement target for oxygen reduction reaction catalysts is to simultaneously improve both the electrochemical activity and durability. To this end, the efficacy of a new highly conductive support that comprises of a 0.5 nm titanium oxynitride film coated by atomic layer deposition onto an array of carbon nanotubes has been investigated. Support effects for pure platinum and for a platinum (50 at %)/nickel alloy have been considered. Oxynitride induces a downshift in the d-band center for pure platinum and fundamentally changes the platinum particle size and spatial distribution. This results in major enhancements in activity and corrosion stability relative to an identically synthesized catalyst without the interlayer. Conversely, oxynitride has a minimal effect on the electronic structure and microstructure, and therefore, on the catalytic performance of platinum-nickel. Calculations based on density functional theory add insight with regard to compositional segregation that occurs at the alloy catalyst-support interface.

Selective ring opening of naphthenic molecules in oil upgrading should result in no loss in molecular weight. Benzocyclopentane (indan) ring opening was studied under hydrogen atmospheric pressure at 609 K over poly-(vinylpyrrolidone)-stabilized Ru, Ir and Pd monometallic and Ru–Ir and Ru–Pd bimetallic nanocatalysts prepared by simultaneous reductions. The particle size (mostly within 2 nm) and their monodispersity were confirmed by transmission electron microscopy, while X-ray photoelectron spectroscopy indicated the bimetallics' alloy structure. Pd catalysts displayed the lowest activity in the ring opening; Ru showed the highest formation of undesired o-xylene and lights. Monometallic Ir displayed the highest activity and selectivity toward 2-ethyltoluene and n-propylbenzene. In bimetallic structures, higher Ir content led to improved catalytic performance. Next to the monometallic Ir catalyst, the newly developed Ru1Ir4/γ-Al2O3 catalyst (with 1 : 4 molar ratio of Ru to Ir) displayed superior single cleavage selectivity as well as lower cracking activity compared to industrial Pt–Ir catalysts at a comparable indan conversion. The study can pave the way in the development of Pt-free Ru-containing catalysts with narrow size distributions for selective ring opening, especially taking into consideration a possibility of their higher S-resistance as compared to the Pt catalysts.

We employed a polypyrrole hydrogel precursor to create a carbon framework that possesses both huge heteroatom content (13 wt% nitrogen and 11 wt% oxygen) and high surface area (945 m 2 g −1 ) that is equally divided between micropores and mesopores. A sodium ion capacitor (NIC, HIC) electrode fabricated from this N and O Functionalized Carbon (NOFC) has tremendous reversible capacity and rate capability, e.g. 437 mA h g −1 at 100 mA g −1 , and 185 mA h g −1 at 1600 mA g −1 . This is among the most favorable reported, and is due to copious nanoporosity that enables fast ion sorption at the many N and O moieties and graphene defects. The NOFC imbues a NIC device with energy–power characteristics that are not only state-of-the-art for Na hybrids, but also rival Li systems: Ragone chart placement is 111 W h kg −1 and 38 W h kg −1 at 67 W kg −1 and 14,550 W kg −1 , respectively, with 90% capacity retention at over 5000 charge/discharge cycles.

We created a unique SnO 2 –Graphene Dual Aerogel (SnO 2 /GDA) nanocomposite with exquisite lithium and sodium ion battery anode performance (LIB, NIB NAB SIB). In parallel we employed electrochemical methods to be the first to analyze the transition from kinetic control to diffusion control for the conversion reaction (SnO 2 +4Li + +4e − ↔Sn+2Li 2 O) vs. for the alloying reaction (Sn+ x Li + + x e − ↔Li x Sn, x ≤4.4). The material displays a high reversible capacity (1299 mA h g −1 for Li at 0.1 A g −1 , 448 mA h g −1 for Na at 0.05 A g −1 ), very good cycling life (148% after 450 cycles for Li, 82% from 20 to 200 cycles for Na), and superb rate capacity retention (450 mA h g −1 for Li at 25 A g −1 , 184 mA h g −1 for Na at 1 Ag −1 ). In fact, these rate capabilities are among the most favorable reported in literature for each system.

We employed a glucose mediated hydrothermal self-assembly method to create a SnO2–carbon nanocomposite with promising electrochemical performance as both a sodium and a lithium ion battery anode (NIBs NABs SIBs, LIBs), being among the best in terms of cyclability and rate capability when tested against Na. In parallel we provide a systematic side-by-side comparison of the sodiation vs. lithiation phase transformations in nano SnO2. The high surface area (338 m2 g−1) electrode is named C–SnO2, and consists of a continuous Li and Na active carbon frame with internally imbedded sub-5 nm SnO2 crystallites of high mass loading (60 wt%). The frame imparts excellent electrical conductivity to the electrode, allows for rapid diffusion of Na and Li ions, and carries the sodiation/lithiation stresses while preventing cycling-induced agglomeration of the individual crystals. C–SnO2 employed as a NIB anode displays a reversible capacity of 531 mA h g−1 (at 0.08 A g−1) with 81% capacity retention after 200 cycles, while capacities of 240, 188 and 133 mA h g−1 are achieved at the much higher rates of 1.3, 2.6 and 5 A g−1. As a LIB anode C–SnO2 maintains a capacity of 1367 mA h g−1 (at 0.5 A g−1) after 400 cycles, and 420 mA h g−1 at 10 A g−1. Combined TEM, XRD and XPS prove that the much lower capacity of SnO2 as a NIB anode is due to the kinetic difficulty of the Na–Sn alloying reaction to reach the terminal Na15Sn4 intermetallic, whereas for Li–Sn the Li22Sn5 intermetallic is readily formed at 0.01 V. Rather, with applied voltage a significant portion of the material effectively shuffles between SnO2 and β-Sn + NaO2. The conversion reaction proceeds differently in the two systems: LiO2 is reduced directly to SnO2 and Li, whereas the NaO2 to SnO2 reaction proceeds through an intermediate SnO phase.

Thin metallic layers of Cu, Cr, or Ag were deposited on Si substrates and then sputtered as in a standard depth profiling mode. The etching was completed by using 1-5 keV Ar + beam, scanned over the surface. The composition of the exposed etched surface was monitored by X-ray photoelectron spectroscopy (XPS) or Auger electron spectroscopy (AES). When the metal-silicon interface was approached, the etching was stopped and the sample surface was analyzed by scanning electron microscopy (SEM) and scanning Auger microscopy (SAM). We observed clusters of metal on the Si substrate. Their characteristic sizes were 30-60 nm for Cu, 60-90 nm for Cr, and 100-200 nm for Ag. The patterns were sensitive to the ion energy - at 1 keV the Cu network was well defined, whereas at 3-5 keV energy the patterns become fuzzy without clear boundaries. The clustering of thin films near the interface can affect the depth profiles in surface analytical techniques, and can be used as a tool to create clusters in nanotechnology.

This is the first report of a hybrid sodium ion capacitor (NIC) with the active materials in both the anode and the cathode being derived entirely from a single precursor: peanut shells, which are a green and highly economical waste globally generated at over 6 million tons per year. The electrodes push the envelope of performance, delivering among the most promising sodiation capacity–rate capability–cycling retention combinations reported in the literature for each materials class. Hence the resultant NIC also offers a state-of-the-art cyclically stable combination of energy and power, not only in respect to previously but also as compared to Li ion capacitors (LICs). The ion adsorption cathode based on Peanut Shell Nanosheet Carbon (PSNC) displays a hierarchically porous architecture, a sheet-like morphology down to 15 nm in thickness, a surface area on par with graphene materials (up to 2396 m2 g−1) and high levels of oxygen doping (up to 13.51 wt%). Scanned from 1.5–4.2 V vs. Na/Na+ PSNC delivers a specific capacity of 161 mA h g−1 at 0.1 A g−1 and 73 mA h g−1 at 25.6 A g−1. A low surface area Peanut Shell Ordered Carbon (PSOC) is employed as an ion intercalation anode. PSOC delivers a total capacity of 315 mA h g−1 with a flat plateau of 181 mA h g−1 occurring below 0.1 V (tested at 0.1 A g−1), and is stable at 10 000 cycles (tested at 3.2 A g−1). The assembled NIC operates within a wide temperature range (0–65 °C), yielding at room temperature (by active mass) 201, 76 and 50 W h kg−1 at 285, 8500 and 16 500 W kg−1, respectively. At 1.5–3.5 V, the hybrid device achieved 72% capacity retention after 10 000 cycles tested at 6.4 A g−1, and 88% after 100 000 cycles at 51.2 A g−1.

Partially ordered but not graphitized carbons are widely employed for sodium and lithium ion battery (NIB and LIB) anodes, either in their pure form or as a secondary supporting phase for oxides, sulfides and insertion electrodes. These “pseudographitic” materials ubiquitously display a poor initial coulombic efficiency (CE), which has been historically attributed to solid electrolyte interface (SEI) formation on their large surface areas (up to ∼2500 m2 g−1). Here we identify the other sources CE loss by examining a pseudographitic carbon with a state-of-the-art capacity (>350 mA h g−1 for NIB, >800 mA h g−1 for LIB), but with a purposely designed low surface area (14.5 m2 g−1) that disqualifies SEI from having a substantial role. During the initial several (

Clusters of independently tailored areal density and size distribution were grown on semiconductor surfaces by molecular beam epitaxy and were used subsequently as masks for selective ion beam modification. Field emission scanning electron microscopy shows sharp interfaces between the amorphous area exposed to ion beams and areas of crystalline silicon covered by clusters. Partial etching of the substrate leads to narrow trenches around the initial cluster site, suggesting significantly enhanced etching near the amorphous-crystalline interface. The results are explained on the basis of a slight density variation in the substrate near the cluster periphery due to a break in symmetry of the recoil atom incorporation. Computer simulations were carried out to further characterize these results, using a program based on the well-established TRIM code to model atomic collision cascades in a matrix. The resulting density distributions correlate well with the experimentally observed wet etching patterns, strongly suggesting a relation between cluster-masking related density variations in the amorphized silicon and the etching rate.

Aluminium nitride thin films were deposited by reactive d.c. magnetron sputtering on various substrates. The analytical tools used to characterise the aluminium nitride thin films were electron beam diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray analysis and polarised infrared reflection. From these techniques the structure, microstructure, chemical state, percentage content of the elements and IR properties of the films were observed and the formation of the AlN compound was confirmed.

Thin films of AlN were deposited at a total gas pressure of 7×10−4 mbar and a nitrogen partial presure of 9×10−5 mbar by reactive d.c. magnetron sputtering. Low-carbon steel 08KP, Si (100) wafers and monocrystal KCl were used as substrates. Electron microprobe analysis (EMA), X-ray photoelectron spectroscopy (XPS), polarised infra-red reflection and infra-red (PIRR) transmission measurements were carried out to characterise these films. The EMA analysis confirms the microcrystalline structure of our films. From an XPS spectrum of the deposited AlN films, we have demonstrated that AlN was formed at these values of total and partial pressures. The PIRR measurements indicate the presence of a phonon at about 680 cm−1, typical for AlN. The deposited films have a high transmittance (about 80%) in the wavelength region between 2.5 and 12 μm.

Low-power pulsed-laser annealing was applied to Zn+-implanted InP samples. In order to avoid surface oxidation during the treatment, the laser irradiation was carried out in inert ambient of nitrogen at different pressures. The analytical techniques used include Rutherford backscattering spectroscopy, reflection high energy electron diffraction, and electrical measurements. The highest carrier activation, about 80%, was achieved at the same laser power density (6.5 MW/cm2) at which the best crystal recovery was obtained.

The structure of (100) silicon implanted with Zn+ ions at an energy of 50 keV was studied. The ion doses were varied from 1×1015 to 1×1017 cm−2 and the beam current density was 10 μA cm−2. The analytical techniques employed for sample characterization included cross‐sectional transmission electron microscopy and x‐ray energy dispersion analysis. The energy deposition of the ion beam was calculated by using computer simulation codes. For the two lower doses of 1×1015 and 1×1016 a crystalline‐to‐amorphous transformation was observed in the implanted layer and this was correlated with the thermal history of the implants and the attendant changes in morphology. In contrast, an amorphous‐to‐crystalline transition was found to occur at higher doses, namely 5×1016 and 1×1017, where the formation of a complex, structured layer consisting of an amorphous phase mixed with crystalline grains of Zn and partly recrystallized Si was identified together with other specific structural features. Detailed characterization ...

Time was introduced in the well-known TRIM code without changing the “event-driven” logic of the program. This modified TRIM code was used to simulate the slowing-down process of fast Cu ions in amorphous Cu targets. Distributions of the radial range and slowing-down time of the ions together with other time-dependent characteristics of the process were obtained at different projectile energies. A comparison was made with the results obtained by Robinson using the time-dependent MAR-LOWE computer code [Phys. Rev. B 40 (1989) 10717].

Wafers of (100) GaAs have been implanted with 140 keV Zn+ ions at off-channeling direction up to a fluence of 1×1014 cm−2. The target temperature was kept at 110±10°C. The defect clusters and the damage depth distributions were investigated by planar and cross-sectional high-resolution transmission electron microscopy (HRTEM and XHRTEM) and were modelled by a MAR-LOWE-based computer code. The experimental mean depth of the damage profile located at about 85 nm exceeds the calculated deposited energy and vacancy distributions by more than 50%. The correlation between the deposited energy density within the cascade and the inner structure of the observed defect clusters is discussed.

This work is part of a series of investigations started a few years ago to study high fluence ion beam effects. Experimental and computer techniques are applied here to the implantation of 40 keV As + in (111) Si samples at doses ranging from 1 × 10 16 to 2 × 10 17 cm −2 . The experimental evolution of the profile was analyzed by 2 MeV RBS spectroscopy. A special procedure was used to deconvolute the RBS data for highly nonhomogeneous layers. The atomic collision cascades were also simulated by a dynamic computer code, based on sputtering yield values and impurity depth distributions resulting from the well-known static code TRIM.SP. The distributions were used as input data to a procedure which takes into account the modification of the stopping power, the surface erosion by sputtering and the lattice relaxation.

Mesa structures and thin membranes are obtained by means of wet anisotropic etching using the etch-stop effect of nitrogen-implanted silicon. Dynamic Monte Carlo simulation is applied to calculate the implanted nitrogen profile. The use in sensor technology of nitrogen ion implantation in silicon with doses as low as 5×10 16 cm −2 is described.

Depth distributions of displaced atoms for boron and arsenic implanted (111) silicon have been studied both by RBS channeling measurements and by a Monte Carlo simulation technique. The experiments and calculations are compared for ion energies of 80 and 160 keV and different doses. The computer code based on TRIM depth distributions takes into account the accumulation, diffusion and migration of the implantation-induced defects.

GaAs 〈100〉 wafers were implanted and later annealed by using three different techniques: furnace thermal annealing (FTA), flash lamp (RTA) and low-power laser annealing (LPLA). The resulting modifications of the structure were studied by RHEED. The RHEED pattern analysis indicates that: (a) A well annealed structure is observed after thermal treatment in furnace at 850 °C for 30 min; (b) the particular RTA employed leads to some texturing, but is not sufficient to provide good structural effects; (c) best annealing under our conditions is obtained by the LPLA technique, especially for low ion doses (less than 1013 cm−2); (d) variable-glancing-angle RHEED is an effective and convenient method to investigate the ion induced disorder in crystals at small depths.

Low‐power annealing by a pulsed laser is used to recover the structure of low‐dose implanted (100) GaAs crystals. Reflection high‐energy electron diffraction with variable glancing incidence is employed to detect the structural changes at different depths in the specimens. The depth dependence of the damage is studied in more detail by Rutherford backscattering analysis. The annealing results depend on the irradiation conditions. A laser energy window below the melting threshold is found within which the structure can be restored to about as high degree of crystallinity as the virgin one, without any visible surface damage. A simple theoretical estimate shows that the temperature rise of the material is far below the melting threshold. This rise is too short in time to cause substantial dopant diffusion; however, it can enhance well the point‐defect mobility.

Semi-insulating Cr-doped (100) GaAs was implanted with Bi+ with energy 40 keV at room temperature in a 7 ° off-axis direction. The implanted dose was varied between 2 × 1015 cm−2 and 1 × 1016 cm−2. The profile evolution was studied experimentally by RBS measurements and theoretically by a new dynamic computer code. It is based on sputtering yield values and impurity depth distributions, obtained by using the static simulation program TRIM.SP.

The effect of 12 MeV electron irradiation of p-type Si-SiO2 structures is studied by Deep Level Transient Spectroscopy (DLTS) measurements. The DLTS spectra of non-irradiated samples exhibit one peak only corresponding to a deep level located in the forbidden gap at 0.56 eV above the valence band edge of the Si matrix. Four additional, shallower levels are found in the spectra after bombardment with high-energy electrons, whereas the peak intensity is dependent on the irradiation dose. The corresponding activation energy of the created defects, as well as the density of the traps and the electron-capture cross sections are evaluated.

Thin films containing iron silicides are prepared by two methods. The first one consists in depositing a-Si:H:Fe thin films by magnetron co-sputtering followed by rapid thermal annealing (RTA). The second one is ion implantation of Fe in a-Si:H thin films and RTA treatment. The samples are characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Rutherford back-scattering (RBS). FTIR spectra show absorption bands typical for β-FeSi2 at 263, 293, 308, 345 and 425 cm−1. It is shown that the optimal concentration of Fe in the co-sputtered films to obtain β-FeSi2 is 35–40% and the optimal RTA temperature is 900°C. XPS spectra show that β-FeSi2 is formed in as-deposited and annealed co-sputtered a-Si:H:Fe and implanted a-Si:H thin films.

The effects of the ambient atmosphere in the annealing chamber on the electrical and structural characteristics of Zn-implanted III-V compound semiconductors, processed by low-power pulsed-laser annealing are presented. The samples were analyzed using several complementary experimental techniques: Reflection high-energy electron diffraction, Rutherford backscattering spectroscopy, Raman spectroscopy, secondary ion mass spectroscopy, and electrical measurements. During the laser beam irradiation in the presence of gas inlet into the annealing chamber the ambient gas atoms diffused well into the target changing the stoichiometry and the electrical parameters. Redistribution of the implanted impurity was also observed. By varying the type of gas used and its pressure, it was possible to achieve electrical activation of up to 80%. It seems all structure and electrical parameters achieve their best values at the same ambient atmosphere and density of the deposited laser power P, e.g., 1.5 atm of ${\mathrm{N}}_{2}$ and $P=6.5 {\mathrm{M}\mathrm{W}/\mathrm{c}\mathrm{m}}^{2}$ for InP.

〈100〉GaAs crystals were implanted with 140 keV Zn ions at random incidence and a dose of 1014 cm−2. Annealing by a low-power pulsed laser was used to recover the radiation damage. The samples were analysed by RHEED and RBS techniques. The effect of the annealing on the recovery of structure defects in GaAs is reported.

A secondary ion mass spectrometer with high energy, angle and mass resolution is used to study the energy and angular distributions of ions sputtered from molybdenum (110) surface under 4 keV argon beam bombardment. The sputtering at different beam orientations is also simulated by the MARLOWE computer code. The sputtering yields, in addition to the angular distribution of sputtered particles are assessed as a function of a given angle and energy.

Transmission sputtering of thin (up to 300 A) gold films bombarded by 10 to 20 keV Ar ions is simulated by using the MARLOWE computer code. The energy spectra, angle of ejection and depth of origin distributions of ejected particles are presented. The results indicate that even for a thin film the cascading of the recoils is sufficient to produce an E−2 energy spectrum and a cosine angular distribution. The evaluated transmission-sputtering yields for various film thicknesses are compared with the amount of gold retained in a silicon substrate in dynamic recoil mixing experiments.

Thin polyimide films deposited on silicon or metal covered glass-ceramic substrates were exposed to ion bombardment at different fluences ranging from 1 × 1012 to 1.5 × 1016 cm−2. The XPS technique was used to study the polymer stoichiometry of the near surface layers (∼ 75 A) before and after the bombardment. The results show that the stoichiometric ratio of O, N and C-groups remains approximately constant with depth for unirradiated samples. A relative enrichment of C (probably in phenyl or CHx groups) occurred in the implanted samples. Scission of CN and C=O bonds was observed, the latter being complete at doses above 1014 cm−2. Desorption of O and N was also found.

Sputtering of copper, nickel and alumium polycrystalline targets by 40 keV Ar + ions is simulated by a NIARLOWE-based computer code. Angle-of-incidence dependence of sputtering yields and depth-of-origin distributions are calculated. The angular distributions and energy spectra of sputtered particles are similar to those found earlier for low-energy sputtering.

Cross-sectional high resolution transmission electron microscopy has been used to obtain direct information on the in-depth radiation damage distribution of weakly damaged GaAs by Si-ion implantation. A comparison is made between the experimental data and the calculated (using TRIM computer simulations) deposited energy by nuclear stopping for the same conditions. In particular a diffusion zone, with 200–300 A width, of high point defect concentration beyond the damage peak is detected. These point defects are interpreted as As interstitials. By direct observation, information concerning the damage- and radiation-enhanced diffusion in implanted III–V compound semiconductors is obtained.

Lattice disordering has been studied both experimentally by RBS-channelling measurements and theoretically by a Monte Carlo calculation technique. Single-crystal (100) silicon has been phosphorus implanted with an energy of 60 keV at room temperature in a 7° off-axis direction. The implanted doses varied between 5 x 10 14 and 4 x 10 15 cm −2 . Channelling measured distribution of displaced atoms is compared with damage profiles in phosphorus implanted silicon calculated by the computer code TRIM.

Reflection high-energy electron diffraction (RHEED) and X-ray photoelectron spectroscopy (XPS) were used to demonstrate the effects of Zn + -ion implantation and subsequent low-power pulsed laser annealing (LPPLA) on the crystallinity and the P/In ratio near the surface of InP. The influence of ion-beam effects during depth profiling by a 1 to 5 keV Ar beam on the composition of surface layers is discussed in terms of XPS data compared to computer simulation results using a dynamic model based on TRIM. Relative enrichment in P of the topmost surface layer of virgin samples along with the P deficiency below the surface is confirmed by both XPS and computer simulation data, the effect being more pronounced for higher energies of the depth-profiling Ar + beam. Severe C and O contamination is found on the ion-implanted InP surface exposed to air. The P/In ratios at and below the surface (to about 10 nm depth) differ from that for the virgin sample. Both RHEED and XPS demonstrate the efficiency of laser pulses at a power density of 6 MW/cm 2 in recovering the structure and stoichiometry of ion-implanted crystals of InP.