Precious Metal Particles Research Articles

Construction of dense film inside capillary wall and SERS application research

The high-density particle distribution in capillary was a crucial factor for enhancing SERS properties and a difficult point in the preparation process. The direct high-temperature method was used to fuse the particles and form a uniform and dense particle distribution on the capillary's inner wall, providing a foundation for enhancing Raman signals. The prepared capillary SERS substrate strongly enhances the rhodamine 6G (R6G) signal, and the RSD values of several characteristic peaks of R6G are about 10 %, demonstrating high sensitivity, uniformity, and stability. Using capillary SERS substrate for detecting goat serum. Embedding precious metal particles into capillary SERS substrate can effectively encapsulate the tested liquid and avoid contamination, which improves the disadvantage of traditional substrates exposing the liquid to air. The prepared capillary SERS substrate could be used for field and biomedical sensitivity detection, providing a theoretical and experimental basis for developing the capillary SERS substrate.

Coaxial 3D printed Al2O3 ceramic continuous-flow fixed-bed reactor with bionic core-shell structure

Continuous-flow fixed-bed reactors (CFBR) have attracted considerable attention owing to their high efficiency and low energy consumption; however, the integrated fabrication of CFBR with core-shell structures remains a great challenge at present. Herein, a facile coaxial three-dimensional (3D) printing strategy was developed for the first time to rapidly and efficiently construct a CFBR with Al2O3 powder and aluminum dihydrogen phosphate (AP) as the outer shell ink, and Al2O3 powder, AP, and polymethyl methacrylate as the inner core ink that is extruded through a customized coaxial needle. Coaxial 3D printing realizes the integral fabrication of ceramic shells and inner porous ceramic carriers. CFBR with an outer wall thickness of 1.2 mm, core diameter of 3.7 mm, and variable length were fabricated, which were enabled with excellent catalytic properties by simply impregnating precious metal particles. The catalytic efficiencies for the reducing of 4-nitrophenol (4-NP) in the 3-cm-length Pd/CFBR, Pt/CFBR, and Ag/CFBR were found 96.9 %, 97.4 %, and 93 % after 10 min, respectively. Combining integrated fabrication, rapid prototyping, and complex architecture formation, coaxial 3D printing provides a novel strategy for directly integrating multifunctional CFBR.

Technology and possibilities of recycling catalysts

The presented article focuses on the possibilities of recycling three types of catalysts. These catalyst types will undergo examination, measurement, and analysis with the aim of identifying which of these catalysts contains the necessary number of precious metals (PGM - Platinum Group Metals). PGM metals are among the rarest and most challenging-to-obtain elements on Earth, carrying a high risk of supply shortage. Nevertheless, they are crucial for the European Union (EU) and the automotive industry. Not every catalyst used in the market is suitable for recycling due to the absence of these precious metal particles.

Efficient recovery of gold from low concentration Au(S2O3)23– solution by fabricating Ag/MoS2 Ohmic contact

The surface decoration of precious metal particles is one of the most effective strategies for improving the photocatalytic activity of semiconductors. In this work, a MoS2-based Ohmic contact was fabricated by depositing Ag nanoparticles on the surface of MoS2 nanosheets (MoS2 NSs) to enhance the photoreduction of Au(Ⅰ) from a low concentration Au(S2O3)23– solution. After the fabrication of Ohmic contact, more efficient interface charge transfer can be achieved under the drive of built-in electric field. As a result, the photogenerated singlet excitons in MoS2 NSs are readily dissociated into free charges with the electrons drifting to Ag NPs, leading to a higher electron concentration on the surface of Ag/MoS2 NSs. The gold recovery of Ag/MoS2 NSs-4.15% reaches up to 96.67% for the low concentration Au(S2O3)23– solution, which is about 3.9 times higher than that of pristine MoS2 NSs (24.82%). The results of this work are encouraging for further development in the surface science of photocatalysis and demonstrate a pathway for efficient gold recovery via photoreduction.

Thermal deactivation mechanism of the commercial Pt/Pd/Rh/CeO2-ZrO2/Al2O3 catalysts aged under different conditions for the aftertreatment of CNG-fueled vehicle exhaust

Commercial three-way catalysts with high-activity and long-term durability are critical for the aftertreatment of compressed natural gas vehicle exhausts to meet increasingly stringent policy requirements, but high concentrations of CH4 and H2O in the exhaust gas make the catalyst susceptible to deactivation. In this work, a series of commercially deactivated and aged honeycomb Pt/Pd/Rh/CeO2-ZrO2/Al2O3 catalysts were obtained by dry-aging, hydrothermal-aging and engine bench-aging methods, and the effects of aging conditions on catalytic performance, surface composition and microstructure evolution were investigated. The combinations of H2-TPR, XRD, Raman, HRTEM, XPS and in situ DRIFTS of CO/CH4 characterizations confirmed that the stability of CeO2-ZrO2 solid solution structure is a key factor affecting the catalytic activity and durability. Hydrothermally-aged catalyst has a relatively stable CeO2-ZrO2 solid solution structure, which ensures a high dispersion of precious metal particles in the form of small particles on the catalyst surface. Dry-aged catalyst shows that more CeO2 crystals have been segregated from CeO2-ZrO2 solid solution, resulting in most precious metal particles in the form of agglomerates. For the deactivated catalysts after engine bench aging, the microstructure was significantly changed with a large number of CeO2 crystals detached from CeO2-ZrO2 solid solution, resulting in more active sites of Platinum Group Metal (PGM) being encapsulated. In situ DRIFTS of CH4 experiments showed that the process of generation and depletion of intermediate species (e.g., methoxy, formate and bicarbonate species) is a matching process. For the deactivated catalysts with fewer active sites, the subsequent reaction steps of these intermediate species to CO2 and H2O are hindered by the accumulation of stable formate and bicarbonate intermediate species.

Highly sensitive SERS detection of IL-6 in serum by Au@Fe3O4 nanoring-based sandwich immunoassay

Detection of tumor markers is a key to realize the early diagnosis of cancer patients and improve the survival rate of patients. However, there are still great challenges in developing a highly sensitive and selective method to detect the tumor marker interleukin-6 (IL-6) of primary liver cancer, because the concentration of IL-6 in biological samples is limited and various interfering substances exist. Herein, a magnetic SERS immunoassay based on Fe3O4 nanoring (R-Fe3O4) was developed. The method could realize quantitative detection in 0.1–1000 pg/mL according to the sandwich principle and the detection limit of IL-6 reached 0.028 pg/mL. The excellent detection capability was mainly attributed to the characteristics of R-Fe3O4. Strong magnetism of R-Fe3O4 can enrich target molecules at low concentration, and the ring structure can facilitate the deposition of precious metal particles due to the high specific surface area, so as to promote the generation of hot spots and form electromagnetic enhancement. The method exhibited high selectivity for the identification of IL-6 and showed favorable detection results for IL-6 in serum samples. The ultra-sensitivity and high selectivity of the magnetic SERS immunoassay based on R-Fe3O4 would exhibit great development prospects in medical detection.

Enhancement of catalytic performance of graphene supported Pt catalysts by Ni and W for hydrogen gas production by hydrothermal gasification of biomass-derived compounds

A more practical approach to reduce the cost of the precious metal catalysts is to replace some of the precious metal particles with non-expensive metals that do not cause considerable loss of catalytic performance. In the present study, Ni and W metal particles deposited on graphene support along with and without Pt particles by ultrasound-assisted wet impregnation that followed chemical and thermal reduction process. The catalytic activities of the resulted catalysts were evaluated by aqueous-phase reforming (APR), an hydrothermal gasification process using glucose solution as feed. Although metal particles on Ni-based catalysts were well dispersed on the support, they had larger particle sizes with a broader size distribution compared to W-based catalysts. The combination of Ni and W metals with Pt showed positive synergy and the catalytic performance of bimetallic catalysts significantly enhanced for conversion of glucose to hydrogen.

Study on the optoelectronic properties of Ag, Pt, Na and Li particles adsorbed on GaAs nanowire arrays

In this paper, COMSOL Multiphysics software based on finite element method was used to design a GaAs nanowire array simulation model absorbed with metal nanoparticles. We studied the effects of the size, position and number of metal nanoparticles on their light absorption, and in this experiment, precious metal (Ag, Pt) and alkali metal (Na, Li) particles adsorbed on nanowires. The results show that the adsorption of metal particles is helpful to improve the light binding capacity of short wavelength nanowire arrays. With the change of the radius, position and number of particles, the nanowires absorbed by Li and Ag nanoparticles showed better light absorption characteristics. The optical trapping effect can be effectively enhanced by increasing the size of particles, the number of surrounding particles and the number of particles which distributed along the nanowire direction appropriately.

Characterization of the Evolution of Noble Metal Particles in a Commercial Three-Way Catalyst: Correlation between Real and Simulated Ageing

Ageing of automotive catalysts is associated to a loss of their functionality and ultimately to a waste of precious resources. For this reason, understanding catalyst ageing phenomena is necessary for the design of long lasting efficient catalysts. The present work has the purpose of studying in depth all the phenomena that occur during ageing, in terms of morphological modification and deactivation of the active materials: precious metal particles and oxidic support. The topic was deeply investigated using specific methodologies (FT-IR, CO chemisorption, FE-SEM) in order to understand the behavior of metals and support, in terms of their surface properties, morphology and dispersion in the washcoat material. A series of commercial catalysts, aged in different conditions, have been analyzed, in order to find correlations between real and simulated ageing conditions. The characterization highlights a series of phenomena linked to the deactivation of the catalysts. Pd nanoparticles undergo a rapid agglomeration, exhibiting a quick loss of dispersion and of active sites with an increase of particles size. The evolution of the support allows highlighting also the contribution of chemical ageing effects. These results were also correlated with performance tests executed on synthetic gas bench, underlining a good correspondence between vehicle and laboratory aged samples and the contribution of chemical poisoning to vehicle aged ones. The collected data are crucial for the development of accelerated laboratory ageing protocols, which are instrumental for the development and testing of long lasting abatement systems.

Phase transformations of Fe(ІІ)-Fe(III) layered dоuble hydroxides of corrosion origin in the aqueous solutions of platinum and palladium

One of the urgent scientific problems is the development of new or alternative to the well-known methods оf the synthesis of biocompatible substances and composites with unique complexes of physicochemical properties (optical, magnetic, catalytic, electrical, bactericidal). Promising substances for the production of compounds of this class are Fe (II)-Fe (III) layered double hydroxides (LDHs) or Green Rust.At present, Green Rust suspensions are already used as nanoreactors for the one stage reduction of precious metal particles (gold and silver), the production of magnetite doped with precious metals and the synthesis of shell nanocomposites. The advantages of using Fe(II)-Fe(III) LNG structures as a reducing agent are the absence of the need to introduce into the system foreign components, such as anions of iron salts, organic substances, including surfactants, as well as the simplicity of the synthesis procedure, carried out without the use of expensive equipment.While the processes of formation of shell nanocomposites Fe3O4&Ag0 and Fe3O4&Au0 in Green Rust suspensions, their physicochemical properties, experience and prospects for practical use in biomedical research are covered in the literature in detail, the lack of comprehensive data on the structure and properties of shell composites based on particles of magnetite of corrosion origin and clusters of platinum and palladium, or magnetite doped with platinum group metals, still remain an unsolved part of this scientific problem.Therefore, the aim of this study was to determine the composition and physicochemical properties of the products of phase transformations of hydroxycarbonate Green Rust of corrosion origin in its contact with aqua forms of platinum and palladium under conditions of free air in the reaction zone.To obtain the primary phase of hydroxycarbonate Green Rust, a disk device was used, the working part of which is made of steel 3. During the synthesis procedure, the steel disk was alternately in contact with aqueous solution and air. Before the start of each experiment, the disk was treated mechanically and chemically to remove the oxide layer and activate the surface of the carbon alloy. The build-up of the GR(CO3)2- layer was performed under conditions of contact of the steel surface with distilled water for an hour, after which the dispersion medium was changed to aqueous solutions of noble metals.Six aqueous sodium chlorine platinate Na2[PtCl6] ‧ 6H2O in the concentration range (Pt 4+) from 0.5 to 10 mg/dm3 was used to obtain platinum-containing solutions, and H2[PdCl4] and PdCl2 with concentrations (Pd 2+) from 0.1 to 10 mg/dm3 were selected to obtain palladium-containing solutions, respectively. The synthesis was performed before the transition of the system to a steady state (70 hours). The studies were based on the following methods: X-ray phase analysis and X-ray fluorescence spectroscopy (X-ray diffraction), thermogravimetry (TG-DTA), photocolorimetry, electrokinetic studies, scanning electron microscopy (SEM), magnetic field and force microscopy, magnetometry.As a result of the conducted experiments, the processes of phase transformations of Fe(II)-Fe(III) LNG of hydroxycarbonate composition of corrosion origin in the presence of aquaforms of platinum and palladium were investigated. The formation of nanosized particles of magnetite on the surface of steel and oxyhydroxides of iron, relics of Fe(II)-Fe(III) LNG and particles of reduced noble metals - in the film of its near-surface layer have been established. It is determined that the phase formation in the system is accompanied by the activation of electrode processes on the steel surface, which lead to the accumulation of Fe2 + cations and hydroxyl anions in the dispersion medium. The typical course of exogenous oxidation of iron-containing compounds is elucidated by thermogravimetry. It is shown that the entry of platinum and palladium cations into the structure of magnetite significantly affects the value of its electrokinetic potential. The method of magnetometry proved that the particles of platinum-doped magnetite have nanometer sizes and belong to superparamagnetic, which opens up prospects for their practical use in biomedicine.

Simulation study for magnetic levitation in pure water exploiting the ultra-high magnetic field gradient product of a hybrid trapped field magnet lens (HTFML)

A hybrid trapped field magnet lens (HTFML) is a promising device that is able to concentrate a magnetic field higher than the applied field continuously, even after removing an external field, which was conceptually proposed by the authors in 2018. In this study, we propose a new additional advantage of the HTFML, which could be applicable for magnetic levitation and separation. The HTFML device consisting of a GdBaCuO bulk cylinder and a GdBaCuO magnetic lens, after the magnetization process from an applied field, Bapp = 10 T, can generate a maximum trapped field, Bc = 11.4 T, as well as an ultra-high magnetic field gradient product, Bz⋅dBz/dz, over ±3000 T2/m at Ts = 20 K, which is higher than that of existing superconducting magnets and large-scale hybrid magnets. Through detailed numerical simulations, the HTFML device is considered for the magnetic separation of a mixture of precious metal particles (Pt, Au, Ag, and Cu) dispersed in pure water, by exploiting the magneto-Archimedes effect. The HTFML can be realized as a compact and mobile desktop-type superconducting bulk magnet system, and there are a wide range of potential industrial applications, such as in the food and medical industries.

Pd model catalysts: Effect of aging duration on lean redispersion

An automotive three-way catalyst (TWC) deteriorates as a function of temperature, time and aging environment. While much effort has gone into formulating durable exhaust catalysts, relatively little attention has been paid to controlling the aging environment on the vehicle with techniques currently in use to protect the catalyst and counteract the increasing demands for higher fuel economy (e.g., overfueling to reduce exhaust temperatures). New engine control methods that are designed to minimize aging may be possible that can reduce the extent of catalyst deactivation and provide a lean environment capable of redispersing many of the precious metal particles. To develop improved engine control methods, detailed experimental information is needed to map the response of the catalyst to different aging conditions. In this report, we examine palladium-based model powder catalysts on ceria–zirconia, which were exposed to three different exhaust compositions, lean-only, rich-only and redox, each at 700°C for three different durations, 20min, 2h and 16h. Residual catalyst activity and metal-support interaction were probed with Water Gas Shift (WGS) reaction and Oxygen Storage Capacity (OSC) measurements. The Pd metal particle size and dispersion were estimated by H2 chemisorption and XRD line broadening. Lean catalyst treatments at 550°C and 700°C were applied to determine the effect on Pd size and catalyst activity. An infrared study of CO adsorption onto the catalysts was used to identify whether Pd crystallite facets were covered by the support after exposure to the redox aging environment then again after the lean treatments were applied. The aging temperature and reducing gas environment significantly deteriorated catalytic activity through a combination of metal oxidation state effects and support interactions, while the aging duration was linked to the extent of Pd sintering reversibility through lean treatments. These insights provide a basis to develop engine control and aftertreatment design strategies to avoid severe aging modes and determine how often to actively intervene to regenerate the catalyst.

Bioleaching of Pyrrhotite by Moderately and Extremely Thermophilic Bacteria

Pyrrhotite ores are always mingled with very finely disseminated gold and other precious metal particles, which raise the disposal of such refractory ores to bacterial leaching level. In this paper, the bioleaching tests of pyrrhotite were carried out in Erlenmeyer flasks with moderately thermophilic Leptospirillum ferriphilum (at 40°C) and extremely thermophilic Acidianus manzaensis(at 65°C). The effects of bacterial strains, temperature, and acid tolerance on the extraction of iron were investigated, and the bioleaching residues were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that high temperature and low pH have important positive effects on the dissolution of iron under abiotic control, and extreme thermophilies are unsuitable for leaching pyrrhotite. As the pH value rapidly increased to above 4.4 and amounts of sulfur and goethite were generated at the initial stage during the process of bioleaching by A. manzaensis, the cell concentration dramatically declined. In comparison, more than 44% extraction of iron was achieved in the presence of L. ferriphilumafter four days of leaching. At the end of bioleaching, jarosite, sulfur and goethite, which could effectively block bioleaching process, were detected on the surface of residues by using XRD and SEM.

Functionalization of Carbon Nanotube-Supported Precious Metal Catalysts by Coverage with Metal Oxide Layers

Precious metals such as Pd, Pt, and Rh have been utilized as the active components of many catalysts. Owing to the high cost of these metals, their loadings in catalysts must be reduced. However, reducing loadings without compromising catalytic performance is difficult. Precious metal catalysts are inevitably deactivated by severe reaction conditions (e.g., high temperature and pressure), which tend to increase of the size of the precious metal particles. Here, we review our recent work on the functionalization of supported precious metal catalysts by coverage with layers of metal oxides such as silica. Coverage with silica layers a few nanometers thick prevents aggregation of the metal particles as well as their detachment from the supports under severe reaction conditions. For example, coverage of supported Pt and Pd electrocatalysts in polymer electrolyte fuel cells with silica layers effectively improves catalyst durability by inhibiting not only particle aggregation but also the diffusion of dissolved metal species out of the catalysts. Coverage of supported precious metal photocatalysts with titania layers also enhances catalytic activity.

Catalytic oxidation of biodiesel fatty acid methyl esters over supported precious metals

Oxidation of biodiesel fuel fatty acid methyl esters (FAMEs) over precious metal catalysts was investigated, using palm oil methyl esters and Jatropha oil methyl esters as representative test compounds. A unique apparatus was designed and used to supply fuel mist directly to the catalyst bed via an air atomizing nozzle normally used in inductively coupled plasma spectrometry. The catalytic oxidation of FAMEs over Pt/Al2O3 resulted in higher light-off temperatures (the temperature at 50 % conversion; T50) and selectivity for CO, as compared with the oxidation of gas oil, suggesting that conventional diesel oxidation catalysts might be insufficient when used with FAME-based biodiesel fuels. Pt exhibited greater activity than Pd or Rh as the catalyst and SiO2 showed superior performance compared with Al2O3 as the support material. Test results demonstrated that there was less affinity between the FAMEs and SiO2 such that, when a SiO2 support was employed, these esters could more readily migrate to active sites on the surfaces of precious metal particles within the catalyst.

Identification of Platinum and Palladium Particles Emitted from Vehicles and Dispersed into the Surface Environment

Platinum, palladium, and rhodium are emitted from vehicle catalytic converters. Until now, the form of precious metal particles in road dust and urban waste has not been identified. This study has located, imaged, and analyzed these particles in road dust and gully waste. Two fragments of catalytic converter have been observed in road dust. They are 40-80 μm in size and covered in many minute particles (<0.3 μm) of either platinum with minor rhodium or palladium. One fragment identified in gully sediment is smaller, 25 μm in diameter, hosting only one attached particle of palladium with minor rhodium. As fragments are washed off roads they begin to disintegrate and the precious metals become detached. Also precious metal-bearing particles have been located in incinerated sewage ash including a 20 μm diameter cluster of <3 μm sized platinum particles that may be the remains of a catalytic converter fragment that has survived incineration. The form of these precious metal-bearing particles described here reveals that as they are dispersed from roads they are likely to be present predominantly as two particle sizes. Either they are attached to larger fragments of catalytic converter or they are released as individual detached tiny <0.3 μm to nanoparticle sizes.

Theory and Applications of High-Power Nanosecond Pulses to Processing of Mineral Complexes

This paper reviews current research in high pulsed power technologies for processing of precious metals containing refractory ores and natural mineral aggregates. This is a branch of experimental engineering physics that critically depends on national priority research projects for its dynamic development. The aim of the manuscript is to show progress in the study of nanosecond processes involved in the disintegration and breaking-up of mineral complexes with fine disseminated precious metals. The manuscript presents results of theoretical and experimental studies of the mechanisms of the nonthermal action of high-power electromagnetic pulses with nanosecond leading edge, pulse duration, and high electric field strength on natural mineral media. Experimental data are presented to confirm the formation of breakdown channels and selective disintegration of mineral complexes as a result of pulse irradiation. This makes for efficient access of lixiviant solutions to precious metal particles and enhances precious metal recovery into lixivia during leaching. The paper shows the advantages of high-energy pulse treatment that provides a stable gain in valuable components recovery (5–80% gain for gold and 20–50% for silver) and at the same time helps to reduce energy consumption and cost of products in the processing of resistant gold-containing ores and beneficiation products from Russian deposits. X-ray photoelectron spectroscopy was used for determining the relationship between electromagnetic pulses energy and the surface chemical composition for pyrite and arsenopyrite. It has been concluded that impulsive treatment influences oxidation and hydrophobicity of the minerals and, therefore, it allows for the control of the hydrophobic–hydrophilic mineral surface balance.

Morphology-dependent nanocatalysis: metal particles

The rapid development of materials science now enables tailoring of metal and metal oxide particles with tunable size and shape at the nanometre level. As a result, nanocatalysis is undergoing an explosive growth, and it has been seen that the size and shape of a catalyst particle tremendously affects the reaction performance. The size effect of metal nanoparticles has been interpreted in terms of the variation in geometric and electronic properties that governs the adsorption and activation of the reactants as well as the desorption of the products. At the same time, it has been verified that the morphology of a catalyst particle, determined by the exposed crystal planes, also considerably affects the catalytic behavior. This is termed as morphology-dependent nanocatalysis: a catalyst particle with an anisotropic shape alters the reaction performance by selectively exposing specific crystal facets. This perspective article initially surveys the recent progress on morphology-dependent nanocatalysis of precious metal particles to emphasise the chemical nature of the morphology effect. Then, the fabrication of transition metal particles with controllable size/morphology is examined, and their shape is correlated with their catalytic properties, with the aim to clarify the structure-reactivity relationship. Finally, the future outlook presents our personal perspectives on the concept of morphology-dependent nanocatalysis of metal particles, which is a rapidly growing topic in heterogeneous catalysis.

Precious Metals in Municipal Solid Waste Incineration Bottom Ash

Municipal solid waste incineration (MSWI) bottom ash contains economically significant levels of silver and gold. Bottom ashes from incinerators at Amsterdam and Ludwigshafen were sampled, processed, and analyzed to determine the composition, size, and mass distribution of the precious metals. In order to establish accurate statistics of the gold particles, a sample of heavy non-ferrous metals produced from 15 tons of wet processed Amsterdam ash was analyzed by a new technology called magnetic density separation (MDS). Amsterdam’s bottom ash contains approximately 10 ppm of silver and 0.4 ppm of gold, which was found in particulate form in all size fractions below 20 mm. The sample from Ludwigshafen was too small to give accurate values on the gold content, but the silver content was found to be identical to the value measured for the Amsterdam ash. Precious metal value in particles smaller than 2 mm seems to derive mainly from waste of electrical and electronic equipment (WEEE), whereas larger precious metal particles are from jewelry and constitute the major part of the economic value. Economical analysis shows that separation of precious metals from the ash may be viable with the presently high prices of non-ferrous metals. In order to recover the precious metals, bottom ash must first be classified into different size fractions. Then, the heavy non-ferrous (HNF) metals should be concentrated by physical separation (eddy current separation, density separation, etc.). Finally, MDS can separate gold from the other HNF metals (copper, zinc). Gold-enriched concentrates can be sold to the precious metal smelter and the copper-zinc fraction to a brass or copper smelter.

Characterisation of carbon supported platinum-ruthenium fuel cell catalysts of different degree of alloying

A series of PtRu/C fuel cell catalysts have been characterised by a combination of transmission electron microscopy, scanning transmission electron microscopy, energy dispersive X-ray microanalysis, X-ray diffraction and inelastic incoherent neutron scattering. The diffraction and microscopy studies show that a range of catalysts with different degrees of alloying can be obtained. It was possible to produce a strongly alloyed catalyst with average particle size below 10 nm. STEM/EDX results on the local compositions of the precious metal particles of different size and composition showed that the larger the particles the larger the Pt/Ru ratio. This indicates that ruthenium appears to prevent the agglomeration of the platinum particles to retain the smaller nanometer size. Inelastic neutron scattering spectroscopy shows that on the alloyed catalysts hydrogen occupies the threefold site, with no evidence for occupation of the on-top sites even under 800 mbar of hydrogen gas. Changes in the region of the out-of-plane C–H vibrational bands of the carbon black support indicated a contribution of the support during catalyst formation treatment by carbothermal reaction at lower temperature. Comparison of HREELS data from single crystal work and vibrational energy values from neutron spectroscopy allows to derive information on the site occupation of atomic hydrogen on finely divided precious metal particles supported on highly absorbing high surface area carbon blacks.