?Catalytically active Au on Titania:? yet another example of a strong metal support interaction (SMSI)?

Metal-Metal Oxide Catalytic Interface Formation and Structural Evolution: A Discovery of Strong Metal-Support Bonding, Ordered Intermetallics, and Single Atoms

In-depth investigation of metal-metal oxide interactions and their corresponding evolution is of paramount importance to heterogeneous catalysis as it allows the understanding and maneuvering of the structure of catalytic motifs. Herein, using a series of core/shell metal/iron oxide (M/FeO_x, M = Pd, Pt, Au) nanoparticles and through a combination of in situ and ex situ electron and X-ray investigations, we revealed anomalous and dissimilar M-FeO_x interactions among different systems under reducing conditions. Pd interacts strongly with FeO_x after high-temperature reductive treatment, featured by the formation of Pd single atoms in the FeO_x matrix and increased Pd-Fe bonding, while Pt transforms into ordered PtFe intermetallics and Pt single atoms immediately upon the coating of FeO_x. In contrast, Au does not manifest strong bonding with FeO_x. As a proof of concept of tailoring metal-metal oxide interactions for catalysis, optimized Pd/FeO_x demonstrates 100% conversion and 86.5% selectivity at 60 °C for acetylene semihydrogenation.

Understanding and application of metal-support interactions in catalysts for CO-PROX

Preferential oxidation of carbon monoxide (CO-PROX) plays a vital role in H₂ purification in the upstream systems of proton exchange membrane fuel cells (PEMFCs) for its high efficiency, low cost and practicability. The key to the application of CO-PROX is the design and preparation of catalysts, and the supported metal catalysts have been the mainstay after decades of development. The metal-support interaction (MSI), which acts as a bridge between the design of supported catalysts and atomic-level theoretical research, has triggered increasing attention. There is a growing body of literature that recognizes the importance of the MSI in heterogeneous catalysis. In this review, the impacts of the MSI including strong metal-support interactions and electronic metal-support interactions on the essential characteristics of supported single atom, nanocluster and nanoparticle catalysts, and therefore, on catalytic behaviors were discussed, respectively, primarily focusing on electron transfer, chemical bonding and the encapsulation of active sites induced by the MSI. We also presented an overview of how the MSI can be utilized to rationally design catalysts to meet target requirements such as high activity, selectivity or stability via appropriate selection and modification of support and active species. The perspectives of the future development for comprehensive understanding of the MSI were also proposed.

Emerging single atom catalysts in gas sensors

Single atom catalysts (SACs) offer unprecedented opportunities for high-efficiency reactions taking place in many important fields of catalytic processes, electrochemistry, and photoreactions. Due to their maximized atomic utilization and unique electronic and chemical properties, SACs can provide high activity and excellent selectivity for gas adsorption and electron transport, leveraging SACs that enhance the detection sensitivity and selectivity to target gases. In the past few years, SACs including both noble (Pt, Pd, Au, etc.) and non-noble (Mn, Ni, Zn etc.) metals have been demonstrated to be very useful in optimizing sensing performances. However, a comprehensive review on this topic is still missing. Herein, we summarize the synthesis technologies of SACs that are applicable to gas sensors. The electronic and chemical interactions between SACs and host sensing materials, which are crucial to sensor functions, are discussed. Then, we highlight the application progress of various SACs in gas sensors. Prospects in the creation of new sensing materials with emerging SACs and versatile supports are also present. Finally, the challenges and prospects of SACs in the future development of sensors are analyzed.

Overturning CO2 Hydrogenation Selectivity with High Activity via Reaction-Induced Strong Metal-Support Interactions

Encapsulation of metal nanoparticles by support-derived materials known as the classical strong metal-support interaction (SMSI) often happens upon thermal treatment of supported metal catalysts at high temperatures (≥500 °C) and consequently lowers the catalytic performance due to blockage of metal active sites. Here, we show that this SMSI state can be constructed in a Ru-MoO₃ catalyst using CO₂ hydrogenation reaction gas and at a low temperature of 250 °C, which favors the selective CO₂ hydrogenation to CO. During the reaction, Ru nanoparticles facilitate reduction of MoO₃ to generate active MoO_3-x overlayers with oxygen vacancies, which migrate onto Ru nanoparticles' surface and form the encapsulated structure, that is, Ru@MoO_3-x. The formed SMSI state changes 100% CH₄ selectivity on fresh Ru particle surfaces to above 99.0% CO selectivity with excellent activity and long-term catalytic stability. The encapsulating oxide layers can be removed via O₂ treatment, switching back completely to the methanation. This work suggests that the encapsulation of metal nanocatalysts can be dynamically generated in real reactions, which helps to gain the target products with high activity.

Support, composition, and ligand effects in partial oxidation of benzyl alcohol using gold–copper clusters

The effect of metallic composition, support, and ligands on catalytic performance using AuCu clusters in benzyl alcohol oxidation is investigated.

Ultra-high thermal stability of sputtering reconstructed Cu-based catalysts

The rational design of high-temperature endurable Cu-based catalysts is a long-sought goal since they are suffering from significant sintering. Establishing a barrier on the metal surface by the classical strong metal-support interaction (SMSI) is supposed to be an efficient way for immobilizing nanoparticles. However, Cu particles were regarded as impossible to form classical SMSI before irreversible sintering. Herein, we fabricate the SMSI between sputtering reconstructed Cu and flame-made LaTiO₂ support at a mild reduction temperature, exhibiting an ultra-stable performance for more than 500 h at 600 °C. The sintering of Cu nanoparticles is effectively suppressed even at as high as 800 °C. The critical factors to success are reconstructing the electronic structure of Cu atoms in parallel with enhancing the support reducibility, which makes them adjustable by sputtering power or decorated supports. This strategy will extremely broaden the applications of Cu-based catalysts at more severe conditions and shed light on establishing SMSI on other metals.

Materials characterization of TiO2 nanotubes decorated by Au nanoparticles for photoelectrochemical applications

The structural and chemical modification of TiO₂ nanotubes (NTs) by the deposition of a well-controlled Au deposit was investigated using a combination of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), Raman measurements, UV-Vis spectroscopy and photoelectrochemical investigations. The fabrication of the materials focused on two important factors: the deposition of Au nanoparticles (NPs) in UHV (ultra high vacuum) conditions (1–2 × 10⁻⁸ mbar) on TiO₂ nanotubes (NTs) having a diameter of ∼110 nm, and modifying the electronic interaction between the TiO₂ NTs and Au nanoparticles (NPs) with an average diameter of about 5 nm through the synergistic effects of SMSI (Strong Metal Support Interaction) and LSPR (Local Surface Plasmon Resonance). Due to the formation of unique places in the form of “hot spots”, the proposed nanostructures proved to be photoactive in the UV-Vis range, where a characteristic gold plasmonic peak was observed at a wavelength of 580 nm. The photocurrent density of Au deposited TiO₂ NTs annealed at 650 °C was found to be much greater (14.7 μA cm⁻²) than the corresponding value (∼0.2 μA cm⁻²) for nanotubes in the as-received state. The IPCE (incident photon current efficiency) spectral evidence also indicates an enhancement of the photoconversion of TiO₂ NTs due to Au NP deposition without any significant change in the band gap energy of the titanium dioxide (E_g ∼3.0 eV). This suggests that a plasmon-induced resonant energy transfer (PRET) was the dominant effect responsible for the photoactivity of the obtained materials.

The structural and chemical modification of TiO₂ NTs by the deposition of a well-controlled Au deposit (0.01 mg cm⁻¹) was investigated using a combination of microscopic (SEM, STEM), analytical measurements (XPS, SERS, UV-Vis, XRD) and photoelectrochemical investigations.

Electronic Metal-Support Interactions for Electrochemiluminescence Signal Amplification

Au nanoparticle-amplified electrochemiluminescence (ECL) signals are generally realized by nanoparticle morphology modification, functionalization, and nanoalloys formation. It remains a great challenge to utilize the intrinsic catalytic activity of spherical Au nanoparticles for ECL performance improvement. In this work, we prepared the oxygen vacancy-rich CoAl-layered double hydroxide (LDH-O_v)-supported spherical Au nanoparticles via alkali etching of LDH and electrodeposition of Au nanoparticles on the surface of LDH. It was found that the luminol ECL signals of the as-prepared system were significantly enhanced by forming the strong electronic metal-support interaction (EMSI) between Au nanoparticles and LDH-O_v. The further mechanism study demonstrated that EMSI can increase the electron density of interfacial Au atom (Au^δ-) due to a redistribution of charge and promote electron transfer between Au species and LDH-O_v. This study not only introduces EMSI to the ECL field but also paves a new way to the applications of the intrinsic activity of spherical Au nanoparticles in ECL signal amplification. We anticipate that EMSI would be applied to other metal nanocatalysts for the development of highly efficient ECL systems.

Oxidative Strong Metal–Support Interactions

The discoveries and development of the oxidative strong metal–support interaction (OMSI) phenomena in recent years not only promote new and deeper understanding of strong metal–support interaction (SMSI) but also open an alternative way to develop supported heterogeneous catalysts with better performance. In this review, the brief history as well as the definition of OMSI and its difference from classical SMSI are described. The identification of OMSI and the corresponding characterization methods are expounded. Furthermore, the application of OMSI in enhancing catalyst performance, and the influence of OMSI in inspiring discoveries of new types of SMSI are discussed. Finally, a brief summary is presented and some prospects are proposed.

The Electrophilicity of Surface Carbon Species in the Redox Reactions of CuO-CeO2 Catalysts

Electronic metal–support interactions (EMSI) describe the electron flow between metal sites and a metal oxide support. It is generally used to follow the mechanism of redox reactions. In this study of CuO‐CeO₂ redox, an additional flow of electrons from metallic Cu to surface carbon species is observed via a combination of operando X‐ray absorption spectroscopy, synchrotron X‐ray powder diffraction, near ambient pressure near edge X‐ray absorption fine structure spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy. An electronic metal–support–carbon interaction (EMSCI) is proposed to explain the reaction pathway of CO oxidation. The EMSCI provides a complete picture of the mass and electron flow, which will help predict and improve the catalytic performance in the selective activation of CO₂, carbonate, or carbonyl species in C1 chemistry.

Composition and properties of RF-sputter deposited titanium dioxide thin films

The photocatalytic properties of titania (TiO₂) have prompted research utilising its useful ability to convert solar energy into electron-hole pairs to drive novel chemistry. The aim of the present work is to examine the properties required for a synthetic method capable of producing thin TiO₂ films, with well defined, easily modifiable characteristics. Presented here is a method of synthesis of TiO₂ nanoparticulate thin films generated using RF plasma capable of homogenous depositions with known elemental composition and modifiable properties at a far lower cost than single-crystal TiO₂. Multiple depositions regimes were examined for their effect on overall chemical composition and to minimise the unwanted contaminant, carbon, from the final film. The resulting TiO₂ films can be easily modified through heating to further induce defects and change the electronic structure, crystallinity, surface morphology and roughness of the deposited thin film.

Size-dependent strong metal-support interaction in TiO2 supported Au nanocatalysts

The strong metal-support interaction (SMSI) has long been studied in heterogonous catalysis on account of its importance in stabilizing active metals and tuning catalytic performance. As a dynamic process taking place at the metal-support interface, the SMSI is closely related to the metal surface properties which are usually affected by the size of metal nanoparticles (NPs). In this work we report the discovery of a size effect on classical SMSI in Au/TiO₂ catalyst where larger Au particles are more prone to be encapsulated than smaller ones. A thermodynamic equilibrium model was established to describe this phenomenon. According to this finding, the catalytic performance of Au/TiO₂ catalyst with uneven size distribution can be improved by selectively encapsulating the large Au NPs in a hydrogenation reaction. This work not only brings in-depth understanding of the SMSI phenomenon and its formation mechanism, but also provides an alternative approach to refine catalyst performance.

Dynamic metal-polymer interaction for the design of chemoselective and long-lived hydrogenation catalysts

Metal catalysts are generally supported on hard inorganic materials because of their high thermochemical stabilities. Here, we support Pd catalysts on a thermochemically stable but "soft" engineering plastic, polyphenylene sulfide (PPS), for acetylene partial hydrogenation. Near the glass transition temperature (~353 K), the mobile PPS chains cover the entire surface of Pd particles via strong metal-polymer interactions. The Pd-PPS interface enables H2 activation only in the presence of acetylene that has a strong binding affinity to Pd and thus can disturb the Pd-PPS interface. Once acetylene is hydrogenated to weakly binding ethylene, re-adsorption of PPS on the Pd surface repels ethylene before it is further hydrogenated to ethane. The Pd-PPS interaction enables selective partial hydrogenation of acetylene to ethylene even in an ethylene-rich stream and suppresses catalyst deactivation due to coke formation. The results manifest the unique possibility of harnessing dynamic metal-polymer interaction for designing chemoselective and long-lived catalysts.

TiO2 Nanotubes with Pt and Pd Nanoparticles as Catalysts for Electro-Oxidation of Formic Acid

In the present work, the magnetron sputtering technique was used to prepare new catalysts of formic acid electrooxidation based on TiO₂ nanotubes decorated with Pt (platinum), Pd (palladium) or Pd + Pt nanoparticles. TiO₂ nanotubes (TiO₂ NTs) with strictly defined geometry were produced by anodization of Ti foil and Ti mesh in a mixture of glycerol and water with ammonium fluoride electrolyte. The above mentioned catalytically active metal nanoparticles (NPs) were located mainly on the top of the TiO₂ NTs, forming 'rings' and agglomerates. A part of metal nanoparticles decorated also TiO₂ NTs walls, thus providing sufficient electronic conductivity for electron transportation between the metal nanoparticle rings and Ti current collector. The electrocatalytic activity of the TiO₂ NTs/Ti foil, decorated by Pt, Pd and/or Pd + Pt NPs was investigated by cyclic voltammetry (CV) and new Pd/TiO₂ NTs/Ti mesh catalyst was additionally tested in a direct formic acid fuel cell (DFAFC). The results so obtained were compared with commercial catalyst-Pd/Vulcan. CV tests have shown for carbon supported catalysts, that the activity of TiO₂ NTs decorated with Pd was considerably higher than that one decorated with Pt. Moreover, for TiO₂ NTs supported Pd catalyst specific activity (per mg of metal) was higher than that for well dispersed carbon supported commercial catalyst. The tests at DFAFC have revealed also that the maximum of specific power for 0.2 Pd/TiO₂ catalyst was 70% higher than that of the commercial one, Pd/Vulcan. Morphological features, and/or peculiarities, as well as surface composition of the resulting catalysts have been studied by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and chemical surface analytical methods (X-ray photoelectron spectroscopy-XPS; Auger electron spectroscopy-AES).

Highly Crystalline Mesoporous Titania Loaded with Monodispersed Gold Nanoparticles: Controllable Metal-Support Interaction in Porous Materials

We report the syntheses of mesoporous Au/TiO₂ hybrid photocatalysts with ordered and crystalline frameworks using co-assembly of organosilane-containing colloidal amphiphile micelles (CAMs) and poly(ethylene oxide)-modified gold nanoparticles (AuNPs) as templates. The assembled CAMs can convert to inorganic silica during calcination at elevated temperatures, providing extraordinary thermal stability to preserve the porosity of TiO₂ and the nanostructures of AuNPs. Well-defined AuNPs supported within mesoporous TiO₂ (Au@mTiO₂) can be prepared using thermal annealing at temperatures up to 800 °C. High-temperature treatment (≥500 °C) under air is found to not only improve the crystallinity of TiO₂ but also induce oxidative strong metal-support interactions (SMSIs) at Au/TiO₂ interfaces. For oxidative SMSIs, the surface oxidation of AuNPs can generate positively charged Au^δ+ species, while TiO₂ gets reduced simultaneously. Using photocatalytic oxidation of benzyl alcohol as a model reaction, Au@mTiO₂ calcined at 600 °C for 12 h exhibited the best activity under UV irradiation, while Au@mTiO₂ calcined at 600 °C for 2 h showed the best activity under visible light. The delicate balance between the crystallinity and porosity of TiO₂ and the SMSIs at Au-TiO₂ interfaces is found to impact the photocatalytic activity of these hybrid materials.

The effect of strong metal–support interaction (SMSI) on Pt–Ti/SiO2 and Pt–Nb/SiO2 catalysts for propane dehydrogenation

The selectivity of Pt NP's (gray) are modified by SMSI oxides (red) leaving exposed small ensembles capable of dehydrogenation, but with limited activity for hydrogenolysis.

Ultrastable Au nanoparticles on titania through an encapsulation strategy under oxidative atmosphere

Supported gold catalysts play a crucial role in the chemical industry; however, their poor on-stream stability because of the sintering of the gold nanoparticles restricts their practical application. The strong metal-support interaction (SMSI), an important concept in heterogeneous catalysis, may be applied to construct the structure of catalysts and, hence, improve their reactivity and stability. Here we report an ultrastable Au nanocatalyst after calcination at 800 °C, in which Au nanoparticles are encapsulated by a permeable TiO_x thin layer induced by melamine under oxidative atmosphere. Owning to the formed TiO_x overlayer, the resulting Au catalyst is resistant to sintering and exhibits excellent activity and stability for catalytic CO oxidation. Furthermore, this special strategy can be extended to colloidal Au nanoparticles supported on TiO₂ and commercial gold catalyst denoted as RR2Ti, providing a universal way to engineer and develop highly stable supported Au catalysts with tunable activity.

Sintering-resistant Au nanoparticles are highly desirable due to their low Tammann temperature. Here, the authors report an ultrastable titania-supported Au nanocatalyst through an encapsulation strategy under oxidative atmosphere.

Cu@ZIF-8 derived inverse ZnO/Cu catalyst with sub-5 nm ZnO for efficient CO2 hydrogenation to methanol

Cu@ZIF-8 derived inverse ZnO/Cu with sub-5 nm ZnO acts as an efficient catalyst for CO₂ hydrogenation to methanol.

Enhanced catalytic activity for CO oxidation by the metal-oxide perimeter of TiO2/nanostructured Au inverse catalysts

We report the effect of metal-oxide interfaces on CO oxidation catalytic activity with inverse TiO₂-nanostructured Au catalysts. The inverse nanocatalysts were prepared by depositing TiO₂via the liquid-phase immersion method on electrochemically synthesized Au nanostructure supports. The catalytic performance for CO oxidation was investigated using various amounts of Ti (i.e. 0.1-1.0 wt%) on two different morphologies of Au nanostructures (i.e. nanoporous and nanorod). In comparing the different Au morphologies, we found an overall higher TOF and lower activation energy for the TiO₂/nanoporous Au than those for the TiO₂/nanorod Au. In addition, the CO oxidation activity increased as the Ti content increased up to 0.5 wt% probably due to active TiO₂-Au interface sites enhancing CO oxidation via the supply of adsorption sites or charge transfer from TiO₂ to Au. However, a higher titania content (i.e. 1.0 wt% TiO₂) resulted in decreased activity caused by high surface coverage of TiO₂ decreasing the number of TiO₂-Au interface sites. These results implied that the perimeter area of the metal-oxide interface played a significant role in determining the catalytic performance for CO oxidation.

Formation of n–n type heterojunction-based tin organic–inorganic hybrid perovskite composites and their functions in the photocatalytic field

n–n type heterojunction MASnI₃/TiO₂ composites before and after calcination form different ohmic contact interfaces and follow different mechanisms.

Atomically dispersed Au catalysts supported on CeO2 foam: controllable synthesis and CO oxidation reaction mechanism

CO oxidation is a typical heterogeneous catalytic reaction. Development of active and stable low-temperature CO oxidation catalysts has been one of the hot topics in the field of catalysis. In this work, we explored the catalytic application of a series of Au catalysts supported on CeO₂ foam using a modified deposition-precipitation method for CO oxidation. Among them, the catalyst with 1.1% Au loading content showed the highest catalytic activity, leading to the CO total conversion at 20 °C. Based on the strategy of stepwise reduction of Au loading content, we finally obtained the atomically monodisperse Au/CeO₂ catalyst with high stability and strong resistance to elevated temperature, on which in situ DRIFTS analysis and DFT study were further performed to study the possible reactive site. Our results implied that the Au atoms on the CeO₂ foam are the more stable sites for CO adsorption on the catalysts.

MoS2-supported gold nanoparticle for CO hydrogenation

Employing dispersion-corrected density functional theory, we examine the geometry, electronic structure, and reactivity of 13-atom Au nanoparticle supported on defect-laden single-layer MoS₂. The planar structure of Au₁₃ favored in isolated phase, transforms into the three-dimensional structure when supported on MoS₂. We find that charge is transferred from MoS₂ to Au₁₃, and that the electron density is also distributed away from the Au₁₃/MoS₂ interfacial region-making Au sites away from the interface catalytically active. Owing to effect of the support, the Au d states become narrower, and the frontier states appear close to the Fermi level. Consequently, in contrast to the reactivity of Au₁₃/TiO₂ toward methanol decomposition, Au₁₃/MoS₂ offers excellent activity toward methanol synthesis, as demonstrated here, via CO hydrogenation.

Classical strong metal-support interactions between gold nanoparticles and titanium dioxide

Supported metal catalysts play a central role in the modern chemical industry but often exhibit poor on-stream stability. The strong metal-support interaction (SMSI) offers a route to control the structural properties of supported metals and, hence, their reactivity and stability. Conventional wisdom holds that supported Au cannot manifest a classical SMSI, which is characterized by reversible metal encapsulation by the support upon high-temperature redox treatments. We demonstrate a classical SMSI for Au/TiO₂, evidenced by suppression of CO adsorption, electron transfer from TiO₂ to Au nanoparticles, and gold encapsulation by a TiO _x overlayer following high-temperature reduction (reversed by subsequent oxidation), akin to that observed for titania-supported platinum group metals. In the SMSI state, Au/TiO₂ exhibits markedly improved stability toward CO oxidation. The SMSI extends to Au supported over other reducible oxides (Fe₃O₄ and CeO₂) and other group IB metals (Cu and Ag) over titania. This discovery highlights the general nature of the classical SMSI and unlocks the development of thermochemically stable IB metal catalysts.

Superior Stability of Au/SiO2 Compared to Au/TiO2 Catalysts for the Selective Hydrogenation of Butadiene

Supported gold nanoparticles are highly selective catalysts for a range of both liquid-phase and gas-phase hydrogenation reactions. However, little is known about their stability during gas-phase catalysis and the influence of the support thereon. We report on the activity, selectivity, and stability of 2-4 nm Au nanoparticulate catalysts, supported on either TiO₂ or SiO₂, for the hydrogenation of 0.3% butadiene in the presence of 30% propene. Direct comparison of the stability of the Au catalysts was possible as they were prepared via the same method but on different supports. At full conversion of butadiene, only 0.1% of the propene was converted for both supported catalysts, demonstrating their high selectivity. The TiO₂-supported catalysts showed a steady loss of activity, which was recovered by heating in air. We demonstrated that the deactivation was not caused by significant metal particle growth or strong metal-support interaction, but rather, it is related to the deposition of carbonaceous species under reaction conditions. In contrast, all the SiO₂-supported catalysts were highly stable, with very limited formation of carbonaceous deposits. It shows that SiO₂-supported catalysts, despite their 2-3 times lower initial activities, clearly outperform TiO₂-supported catalysts within a day of run time.

Template growth of Au, Ni and Ni–Au nanoclusters on hexagonal boron nitride/Rh(111): a combined STM, TPD and AES study

The unique electronic structure of hexagonal boron nitride/Rh(111) promotes the template growth of Au, Ni, and Ni–Au bimetallic nanoclusters, as well as the formation of an unusual core–shell nanostructure.

Room temperature synthesis of reduced TiO2 and its application as a support for catalytic hydrogenation

Reduced TiO₂ (TiO_2−x) with a controllable reduction degree was synthesized, which can promote the catalytic hydrogenation of N-heterocycle as a catalyst support.

Plasmon induced enhanced photocatalytic activity of gold loaded hydroxyapatite nanoparticles for methylene blue degradation under visible light

A facile surfactant free wet-precipitation process was employed to prepare hydroxyapatite (HAp) nanoparticles.

Influence of Metal Oxides on Platinum Activity towards Methanol Oxidation in H2SO4 solution

Pt-CeO2 /C, Pt-TiO2 /C, and Pt-ZrO2 /C electrocatalysts were prepared by using a modified microwave-assisted polyol process. Physical characterization was performed by using XRD, TEM, and EDX analyses. The incorporation of different metal oxides increased the dispersion degree of Pt nanoparticles and reduced their diameter to 2.50 and 2.33 nm when TiO2 and ZrO2 were introduced to Pt/C, respectively. The electrocatalytic activity of various electrocatalysts was examined towards methanol oxidation in H2 SO4 solution by using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Among the studied composites, Pt-ZrO2 /C was selected to be a candidate electrocatalyst for better electrochemical performance in direct methanol fuel cells.

Precise AuxPt₁-x Alloy Nanoparticle Array of Tunable Composition for Catalytic Applications

A 3-dimensional Block Copolymer Micellar nanoLithography (BCML) process was used to prepare Au_xPt_1−x alloy nanoparticles (NPs) monodisperse in size and composition, strongly anchored onto SiO₂-particles (0.2 wt.% Au_xPt_1−x/SiO₂). The particles possess a face-centered cubic (fcc) crystal structure and their size could be varied from 3–12 nm. We demonstrate the uniformity of the Au/Pt composition by analyzing individual NPs by energy-dispersive X-ray spectroscopy. The strongly bound Au_xPt_1−x NPs catalyzed the oxidation of CO with high activity. Thermal ageing experiments in pure CO₂ as well as in ambient atmosphere demonstrated stability of the size distribution for times as long as 22 h.

Structure determination of the rutile-TiO2(110)-(1 × 2) surface using total-reflection high-energy positron diffraction (TRHEPD)

Detailed structure of the rutile-TiO₂(110)-(1 × 2) has been determined using the newly developed technique of total-reflection high-energy positron diffraction (TRHEPD).