Showing papers on "Catalysis published in 2009"

Metal–organic framework materials as catalysts

Abstract: A critical review of the emerging field of MOF-based catalysis is presented. Discussed are examples of: (a) opportunistic catalysis with metal nodes, (b) designed catalysis with framework nodes, (c) catalysis by homogeneous catalysts incorporated as framework struts, (d) catalysis by MOF-encapsulated molecular species, (e) catalysis by metal-free organic struts or cavity modifiers, and (f) catalysis by MOF-encapsulated clusters (66 references).

Iron-based catalysts with improved oxygen reduction activity in polymer electrolyte fuel cells.

Abstract: Iron-based catalysts for the oxygen-reduction reaction in polymer electrolyte membrane fuel cells have been poorly competitive with platinum catalysts, in part because they have a comparatively low number of active sites per unit volume. We produced microporous carbon-supported iron-based catalysts with active sites believed to contain iron cations coordinated by pyridinic nitrogen functionalities in the interstices of graphitic sheets within the micropores. We found that the greatest increase in site density was obtained when a mixture of carbon support, phenanthroline, and ferrous acetate was ball-milled and then pyrolyzed twice, first in argon, then in ammonia. The current density of a cathode made with the best iron-based electrocatalyst reported here can equal that of a platinum-based cathode with a loading of 0.4 milligram of platinum per square centimeter at a cell voltage of >/=0.9 volt.

Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts

Abstract: Zeolites-microporous crystalline aluminosilicates-are widely used in petrochemistry and fine-chemical synthesis because strong acid sites within their uniform micropores enable size- and shape-selective catalysis. But the very presence of the micropores, with aperture diameters below 1 nm, often goes hand-in-hand with diffusion limitations that adversely affect catalytic activity. The problem can be overcome by reducing the thickness of the zeolite crystals, which reduces diffusion path lengths and thus improves molecular diffusion. This has been realized by synthesizing zeolite nanocrystals, by exfoliating layered zeolites, and by introducing mesopores in the microporous material through templating strategies or demetallation processes. But except for the exfoliation, none of these strategies has produced 'ultrathin' zeolites with thicknesses below 5 nm. Here we show that appropriately designed bifunctional surfactants can direct the formation of zeolite structures on the mesoporous and microporous length scales simultaneously and thus yield MFI (ZSM-5, one of the most important catalysts in the petrochemical industry) zeolite nanosheets that are only 2 nm thick, which corresponds to the b-axis dimension of a single MFI unit cell. The large number of acid sites on the external surface of these zeolites renders them highly active for the catalytic conversion of large organic molecules, and the reduced crystal thickness facilitates diffusion and thereby dramatically suppresses catalyst deactivation through coke deposition during methanol-to-gasoline conversion. We expect that our synthesis approach could be applied to other zeolites to improve their performance in a range of important catalytic applications.

Palladium- and Copper-Catalyzed Arylation of Carbon-Hydrogen Bonds

Abstract: The transition-metal-catalyzed functionalization of C-H bonds is a powerful method for generating carbon-carbon bonds. Although significant advances to this field have been reported during the past decade, many challenges remain. First, most of the methods are substrate-specific and thus cannot be generalized. Second, conversions of unactivated (i.e., not benzylic or alpha to heteroatom) sp(3) C-H bonds to C-C bonds are rare, with most examples limited to t-butyl groups, a conversion that is inherently simple because there are no beta-hydrogens that can be eliminated. Finally, the palladium, rhodium, and ruthenium catalysts routinely used for the conversion of C-H bonds to C-C bonds are expensive. Catalytically active metals that are cheaper and less exotic (e.g., copper, iron, and manganese) are rarely used. This Account describes our attempts to provide solutions to these three problems. We have developed a general method for directing-group-containing arene arylation by aryl iodides. Using palladium acetate as the catalyst, we arylated anilides, benzamides, benzoic acids, benzylamines, and 2-substituted pyridine derivatives under nearly identical conditions. We have also developed a method for the palladium-catalyzed auxiliary-assisted arylation of unactivated sp(3) C-H bonds. This procedure allows for the beta-arylation of carboxylic acid derivatives and the gamma-arylation of amine derivatives. Furthermore, copper catalysis can be used to mediate the arylation of acidic arene C-H bonds (i.e., those with pK(a) values <35 in DMSO). Using a copper iodide catalyst in combination with a base and a phenanthroline ligand, we successfully arylated electron-rich and electron-deficient heterocycles and electron-poor arenes possessing at least two electron-withdrawing groups. The reaction exhibits unusual regioselectivity: arylation occurs at the most hindered position. This copper-catalyzed method supplements the well-known C-H activation/borylation methodology, in which functionalization usually occurs at the least hindered position. We also describe preliminary investigations to determine the mechanisms of these transformations. We anticipate that other transition metals, including iron, nickel, cobalt, and silver, will also be able to facilitate deprotonation/arylation reaction sequences.

Thermally stable Pt/mesoporous silica core–shell nanocatalysts for high-temperature reactions

Abstract: Recent advances in colloidal synthesis enabled the precise control of the size, shape and composition of catalytic metal nanoparticles, enabling their use as model catalysts for systematic investigations of the atomic-scale properties affecting catalytic activity and selectivity. The organic capping agents stabilizing colloidal nanoparticles, however, often limit their application in high-temperature catalytic reactions. Here, we report the design of a high-temperature-stable model catalytic system that consists of a Pt metal core coated with a mesoporous silica shell (Pt@mSiO2). Inorganic silica shells encaged the Pt cores up to 750 ∘C in air and the mesopores providing direct access to the Pt core made the Pt@mSiO2 nanoparticles as catalytically active as bare Pt metal for ethylene hydrogenation and CO oxidation. The high thermal stability of Pt@mSiO2 nanoparticles enabled high-temperature CO oxidation studies, including ignition behaviour, which was not possible for bare Pt nanoparticles because of their deformation or aggregation. The results suggest that the Pt@mSiO2 nanoparticles are excellent nanocatalytic systems for high-temperature catalytic reactions or surface chemical processes, and the design concept used in the Pt@mSiO2 core–shell catalyst can be extended to other metal/metal oxide compositions. Colloidal synthesis can help to precisely control the shape and composition of catalytic metal nanoparticles, but it has so far proved difficult to use these particles in high-temperature reactions. Core–shell structures capable of isolating Pt-mesoporous silica nanoparticles have now been shown to be catalytically active for ethylene hydrogenation and CO oxidation at high temperature.

Palladium Nanoparticles on Graphite Oxide and Its Functionalized Graphene Derivatives as Highly Active Catalysts for the Suzuki−Miyaura Coupling Reaction

Abstract: Pd2+-exchanged graphite oxide and chemically derived graphenes therefrom were employed as supports for Pd nanoparticles. The influence of catalyst preparation, carbon functionalization, and catalyst morphology on the catalytic activity in the Suzuki−Miyaura coupling reactions was investigated. The catalysts were characterized by means of spectroscopy (FT-IR, solid-state 13C NMR, AAS, XPS), X-ray scattering (WAXS), surface area analysis (BET, methylene blue adsorption), and electron microscopy (TEM, ESEM). In contrast to the conventional Pd/C catalyst, graphite oxide and graphene-based catalysts gave much higher activities with turnover frequencies exceeding 39 000 h−1, accompanied by very low palladium leaching (<1 ppm).

Palladium in fuel cell catalysis

Abstract: Carbon supported platinum is commonly used as anode and cathode electrocatalyst in low-temperature fuel cells fuelled with hydrogen or low molecular weight alcohols. The cost of Pt and the limited world supply are significant barriers to the widespread use of these types of fuel cells. Moreover, platinum used as anode material is readily poisoned by carbon monoxide, present in the reformate gas used as H2 carrier in the case of polymer electrolyte fuel cells, and a byproduct of alcohol oxidation in the case of direct alcohol fuel cells. In addition, Pt alone does not present satisfactory activity for the oxygen reduction reaction when used as cathode material. For all these reasons, binary and ternary platinum-based catalysts and non-platinum-based catalysts have been tested as electrode materials for low temperature fuel cells. Palladium and platinum have very similar properties because they belong to the same group in the periodic table. The activity for the oxygen reduction reaction (ORR) of Pd is only slightly lower than that of Pt, and by addition of a suitable metal, such as Co or Fe, the ORR activity of Pd can overcome that of Pt. Conversely, the activity for the hydrogen oxidation reaction (HOR) of Pd is considerably lower than that of Pt, but by adding of a very small amount (5 at%) of Pt, the HOR activity of Pd attains that of pure Pt. This paper presents an overview of Pd and Pd-containing catalysts, tested both as anode and cathode materials for low-temperature fuel cells.

Fe-g-C3N4-Catalyzed Oxidation of Benzene to Phenol Using Hydrogen Peroxide and Visible Light

Abstract: A bioinspired iron-based catalyst with semiconductor photocatalytic functions in combination with a high surface area holds promise for synthetic chemistry via combining photocatalysis with organosynthesis. Here exemplified for phenol synthesis, Fe-g-C3N4/SBA-15 is able to oxidize benzene to phenol with H2O2 even without the aid of strong acids or alkaline promoters. By taking advantage of both catalysis and photocatalyisis functions of g-C3N4 nanoparticles, the yield of the phenol can be markedly promoted.

Enhanced Sulfur and Coking Tolerance of a Mixed Ion Conductor for SOFCs: BaZr0.1Ce0.7Y0.2–xYbxO3–δ

Abstract: The anode materials that have been developed for solid oxide fuel cells (SOFCs) are vulnerable to deactivation by carbon buildup (coking) from hydrocarbon fuels or by sulfur contamination (poisoning). We report on a mixed ion conductor, BaZr(0.1)Ce(0.7)Y(0.2-)(x)Yb(x)O(3-delta), that allows rapid transport of both protons and oxide ion vacancies. It exhibits high ionic conductivity at relatively low temperatures (500 degrees to 700 degrees C). Its ability to resist deactivation by sulfur and coking appears linked to the mixed conductor's enhanced catalytic activity for sulfur oxidation and hydrocarbon cracking and reforming, as well as enhanced water adsorption capability.

Highly stable crystalline catalysts based on a microporous metal-organic framework and polyoxometalates.

Abstract: A series of remarkable crystalline compounds [Cu2(BTC)4/3(H2O)2]6[HnXM12O40]·(C4H12N)2 (X = Si, Ge, P, As; M = W, Mo) were obtained from the simple one-step hydrothermal reaction of copper nitrate, benzentricaboxylate (BTC), and different Keggin polyoxometalates (POMs). In these compounds, the catalytically active Keggin polyanions were alternately arrayed as noncoordinating guests in the cuboctahedral cages of a Cu-BTC-based metal−organic framework (MOF) host matrix. X-ray crystallographic analyses, TG, FT-IR, UV−vis, N2 adsorption studies, and acid−base titration demonstrated their high stability and toleration for thermal and acid−base conditions. No POM leaching or framework decomposition was observed in our study. The representative acid catalytic performance of a compound containing PW12 species was assessed through the hydrolysis of esters in excess water, which showed high catalytic activity and can be used repeatedly without activity loss. Moreover, catalytic selectivity, which is dependent on th...

From hydrogenases to noble metal-free catalytic nanomaterials for H2 production and uptake.

Abstract: Interconversion of water and hydrogen in unitized regenerative fuel cells is a promising energy storage framework for smoothing out the temporal fluctuations of solar and wind power. However, replacement of presently available platinum catalysts by lower-cost and more abundant materials is a requisite for this technology to become economically viable. Here, we show that the covalent attachment of a nickel bisdiphosphine–based mimic of the active site of hydrogenase enzymes onto multiwalled carbon nanotubes results in a high–surface area cathode material with high catalytic activity under the strongly acidic conditions required in proton exchange membrane technology. Hydrogen evolves from aqueous sulfuric acid solution with very low overvoltages (20 millivolts), and the catalyst exhibits exceptional stability (more than 100,000 turnovers). The same catalyst is also very efficient for hydrogen oxidation in this environment, exhibiting current densities similar to those observed for hydrogenase-based materials.

Au@ZIF-8: CO Oxidation over Gold Nanoparticles Deposited to Metal−Organic Framework

Abstract: Gold nanoparticles (NPs) were deposited to a zeolite-type metal-organic framework (MOF) by a simple solid grinding method. A catalyst, Au@ZIF-8, represents the first example of an active catalyst in CO oxidation by using a MOF as a novel support for noble metal NPs. The catalytic activity for CO oxidation is improved along with increasing Au loadings, and the highest catalytic activity is obtained for 5.0 wt % Au@ZIF-8, which presents half conversion of CO at approximately 170 degrees C. Gold NPs are close to being monodisperse and have no aggregation during catalytic reaction, and the catalytic activity is reproducible.

Catalytic Hydrogenation of Carbon Dioxide Using Ir(III)-Pincer Complexes

Abstract: Catalytic hydrogenation of carbon dioxide in aqueous potassium hydroxide was performed using a newly synthesized isopropyl-substituted PNP-pincer iridium trihydride complex as a catalyst. Potassium formate was obtained with turnover numbers up to 3 500 000 and a turnover frequency of 150 000 h−1, both of which are the highest values reported to date.

Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process

Abstract: Hydrogen peroxide (H2O2) is an important disinfectant and bleach and is currently manufactured from an indirect process involving sequential hydrogenation/oxidation of anthaquinones. However, a direct process in which H2 and O2 are reacted would be preferable. Unfortunately, catalysts for the direct synthesis of H2O2 are also effective for its subsequent decomposition, and this has limited their development. We show that acid pretreatment of a carbon support for gold-palladium alloy catalysts switches off the decomposition of H2O2. This treatment decreases the size of the alloy nanoparticles, and these smaller nanoparticles presumably decorate and inhibit the sites for the decomposition reaction. Hence, when used in the direct synthesis of H2O2, the acid-pretreated catalysts give high yields of H2O2 with hydrogen selectivities greater than 95%.

Electron-transfer photoredox catalysis: development of a tin-free reductive dehalogenation reaction.

Abstract: We report an operationally simple, tin-free reductive dehalogenation system utilizing the well-known visible-light-activated photoredox catalyst Ru(bpy)3Cl2 in combination with iPr2NEt and HCO2H or Hantzsch ester as the hydrogen atom donor. Activated C−X bonds may be reduced in good yields with excellent functional-group tolerance and chemoselectivity over aryl and vinyl C−X bonds. The proposed mechanism involves visible-light excitation of the catalyst, which is reduced by the 3° amine to produce the single-electron reducing agent Ru(bpy)3+. A subsequent single-electron transfer generates the alkyl radical, which is quenched by abstraction of a hydrogen atom. Reductions can be accomplished on a preparative scale with as little as 0.05 mol % Ru catalyst.

Coordinatively Unsaturated Al3+ Centers as Binding Sites for Active Catalyst Phases of Platinum on γ-Al2O3

Abstract: In many heterogeneous catalysts, the interaction of metal particles with their oxide support can alter the electronic properties of the metal and can play a critical role in determining particle morphology and maintaining dispersion. We used a combination of ultrahigh magnetic field, solid-state magic-angle spinning nuclear magnetic resonance spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy coupled with density functional theory calculations to reveal the nature of anchoring sites of a catalytically active phase of platinum on the surface of a γ-Al 2 O 3 catalyst support material. The results obtained show that coordinatively unsaturated pentacoordinate Al 3+ (Al 3+ penta ) centers present on the (100) facets of the γ-Al 2 O 3 surface are anchoring Pt. At low loadings, the active catalytic phase is atomically dispersed on the support surface (Pt/Al 3+ penta = 1), whereas two-dimensional Pt rafts form at higher coverages.

Nanostructured Cobalt Oxide Clusters in Mesoporous Silica as Efficient Oxygen‐Evolving Catalysts

Abstract: Light, inexpensive, effective: Nanostructured Co(3)O(4) clusters (see picture) in mesoporous silica are the first example of a nanometer-sized multielectron catalyst made of a first-row transition-metal oxide that evolves oxygen from water efficiently. The nanorod bundle structure of the catalyst results in a very large surface area, an important factor contributing to the high turnover frequency.

Organotransition Metal Chemistry: From Bonding to Catalysis

Abstract: Structure and bonding -- Dative liquids -- Covalent (X type) ligands bound through metal-carbon and metal-hydrogen bonds -- Covalent (X type) ligands bound through metal-heteroatom bonds -- Ligand substitution reactions -- Oxidative addition of nonpolar reagents -- Oxidative addition of polar reagents -- Reductive elimination -- Migratory insertion reactions -- Elimination reactions -- Nucleophilic attack on coordinated ligands -- Electrophilic attack on coordinated ligands -- Metal-ligand multiple bonds -- Principles of catalysis (written with Prof. Patrick J. Walsh) -- Homongeneous hydrogenation -- Hydrofunctionalization and oxidative functionalization of olefins -- Catalytic carbonylation -- Catalytic C-H functionalization -- Transition metal-catalyzed coupling reactions -- Allylic substitution -- Metathesis of olefins and alkynes -- Polymerization and oligomerization of olefins.

Nanostructured Cobalt Oxide Clusters in Mesoporous Silica as Efficient Oxygen-Evolving Catalysts

Abstract: Author(s): Jiao, Feng | Abstract: The development of integrated artificial photosynthetic systems for the direct conversion of carbon dioxide and water to fuel depends on the availability of efficient and robust catalysts for the chemical transformations. Catalysts need to exhibit turnover frequency (TOF) and density (hence size) commensurate with the solar flux at ground level (1000Wm2, airmass (AM) 1.5)[1] to avoid wasting of incident solar photons. For example, a catalyst with a TOF of 100 s1 requires a density of one catalytic site per square nanometer. Catalysts with lower rates or taking up a larger space will require a high-surface-area, nanostructured support that affords tens to hundreds of catalytic sites per square nanometer. Furthermore, catalysts need to operate close to the thermodynamic potential of the redox reaction so that a maximum fraction of the solar photon energy is converted to chemical energy. Stability considerations favor all-inorganic oxide materials, as does avoidance of harsh reaction conditions of pH value or temperature.

Subnanometre platinum clusters as highly active and selective catalysts for the oxidative dehydrogenation of propane.

Abstract: Small clusters are known to possess reactivity not observed in their bulk analogues, which can make them attractive for catalysis. Their distinct catalytic properties are often hypothesized to result from the large fraction of under-coordinated surface atoms. Here, we show that size-preselected Pt(8-10) clusters stabilized on high-surface-area supports are 40-100 times more active for the oxidative dehydrogenation of propane than previously studied platinum and vanadia catalysts, while at the same time maintaining high selectivity towards formation of propylene over by-products. Quantum chemical calculations indicate that under-coordination of the Pt atoms in the clusters is responsible for the surprisingly high reactivity compared with extended surfaces. We anticipate that these results will form the basis for development of a new class of catalysts by providing a route to bond-specific chemistry, ranging from energy-efficient and environmentally friendly synthesis strategies to the replacement of petrochemical feedstocks by abundant small alkanes.

On the origin of the cobalt particle size effects in Fischer-Tropsch catalysis.

Abstract: The effects of metal particle size in catalysis are of prime scientific and industrial importance and call for a better understanding. In this paper the origin of the cobalt particle size effects in Fischer−Tropsch (FT) catalysis was studied. Steady-State Isotopic Transient Kinetic Analysis (SSITKA) was applied to provide surface residence times and coverages of reaction intermediates as a function of Co particle size (2.6−16 nm). For carbon nanofiber supported cobalt catalysts at 210 °C and H2/CO = 10 v/v, it appeared that the surface residence times of reversibly bonded CHx and OHx intermediates increased, whereas that of CO decreased for small (<6 nm) Co particles. A higher coverage of irreversibly bonded CO was found for small Co particles that was ascribed to a larger fraction of low-coordinated surface sites. The coverages and residence times obtained from SSITKA were used to describe the surface-specific activity (TOF) quantitatively and the CH4 selectivity qualitatively as a function of Co particl...

Aromatic Production from Catalytic Fast Pyrolysis of Biomass-Derived Feedstocks

Abstract: The conversion of biomass compounds to aromatics by thermal decomposition in the presence of catalysts was investigated using a pyroprobe analytical pyrolyzer The first step in this process is the thermal decomposition of the biomass to smaller oxygenates that then enter the catalysts pores where they are converted to CO, CO2, water, coke and volatile aromatics The desired reaction is the conversion of biomass into aromatics, CO2 and water with the undesired products being coke and water Both the reaction conditions and catalyst properties are critical in maximizing the desired product selectivity High heating rates and high catalyst to feed ratio favor aromatic production over coke formation Aromatics with carbon yields in excess of 30 molar carbon% were obtained from glucose, xylitol, cellobiose, and cellulose with ZSM-5 (Si/Al = 60) at the optimal reactor conditions The aromatic yield for all the products was similar suggesting that all of these biomass-derived oxygenates go through a common intermediate At lower catalyst to feed ratios volatile oxygenates are formed including furan type compounds, acetic acid and hydroxyacetaldehyde The product selectivity is dependent on both the size of the catalyst pores and the nature of the active sites Five catalysts were tested including ZSM-5, silicalite, beta, Y-zeolite and silica–alumina ZSM-5 had the highest aromatic yields (30% carbon yield) and the least amount of coke

Asymmetric hydrogenation, transfer hydrogenation and hydrosilylation of ketones catalyzed by iron complexes.

Abstract: The conventional homogeneous catalysts for the enantioselective hydrogenation or transfer hydrogenation of ketones are based on platinum metals and, in particular, ruthenium. This method provides valuable enantiopure alcohols for the fine chemical industries. This tutorial review summarizes recent successes in replacing expensive and toxic ruthenium in these catalysts with “greener” iron substitutes including my lab’s recent progress in this area using iron complexes containing readily-prepared tetradentate ligands. It will enlighten chemists interested in homogeneous catalysis and asymmetric synthesis.

Ternary Pt/Rh/SnO2 electrocatalysts for oxidizing ethanol to CO2.

Abstract: The development of a direct ethanol fuel cell has been hampered by ethanol’s inefficient and slow oxidation. A ternary electrocatalyst consisting of platinum and rhodium deposited on carbon-supported tin dioxide nanoparticles is now shown to oxidize ethanol to carbon dioxide with high efficiency by splitting C–C bonds at room temperature. Ethanol, with its high energy density, likely production from renewable sources and ease of storage and transportation, is almost the ideal combustible for fuel cells wherein its chemical energy can be converted directly into electrical energy. However, commercialization of direct ethanol fuel cells has been impeded by ethanol’s slow, inefficient oxidation even at the best electrocatalysts1,2. We synthesized a ternary PtRhSnO2/C electrocatalyst by depositing platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles that is capable of oxidizing ethanol with high efficiency and holds great promise for resolving the impediments to developing practical direct ethanol fuel cells. This electrocatalyst effectively splits the C–C bond in ethanol at room temperature in acid solutions, facilitating its oxidation at low potentials to CO2, which has not been achieved with existing catalysts. Our experiments and density functional theory calculations indicate that the electrocatalyst’s activity is due to the specific property of each of its constituents, induced by their interactions. These findings help explain the high activity of Pt–Ru for methanol oxidation and the lack of it for ethanol oxidation, and point to the way to accomplishing the C–C bond splitting in other catalytic processes.

Cross-laboratory experimental study of non-noble-metal electrocatalysts for the oxygen reduction reaction

Abstract: Nine non-noble-metal catalysts (NNMCs) from five different laboratories were investigated for the catalysis of O2 electroreduction in an acidic medium. The catalyst precursors were synthesized by wet impregnation, planetary ball milling, a foaming-agent technique, or a templating method. All catalyst precursors were subjected to one or more heat treatments at 700−1050 °C in an inert or reactive atmosphere. These catalysts underwent an identical set of electrochemical characterizations, including rotating-disk-electrode and polymer−electrolyte membrane fuel cell (PEMFC) tests and voltammetry under N2. Ex situ characterization was comprised of X-ray photoelectron spectroscopy, neutron activation analysis, scanning electron microscopy, and N2 adsorption and its analysis with an advanced model for carbonaceous powders. In PEMFC, several NNMCs display mass activities of 10−20 A g−1 at 0.8 V versus a reversible hydrogen electrode, and one shows 80 A g−1. The latter value corresponds to a volumetric activity of ...

Oleylamine-mediated synthesis of Pd nanoparticles for catalytic formic acid oxidation.

Abstract: We report a facile synthesis of monodisperse Pd nanoparticles by the reduction of Pd(acac)2 with oleylamine and borane tributylamine complex. The oleylamine-coated Pd nanoparticles are readily “cleaned” with a 99% acetic acid wash, and the Pd particles supported on Ketjen carbon are catalytically active for formic acid oxidation in HClO4 solution. The catalyst shows no obvious activity degradation after 1500 cyclic voltammetry cycles under ambient conditions. These Pd particles hold promise as a highly active non-Pt catalyst for fuel cell applications.

Highly Selective Catalytic Conversion of Phenolic Bio‐Oil to Alkanes

Abstract: Oil and water: A new energy-efficient and atom-economical catalytic route for the production of alkanes and methanol by upgrading the phenolic fraction of bio-oil has been developed. The one-pot aqueous-phase hydrodeoxygenation process is based on two catalysts facilitating consecutive hydrogenation, hydrolysis, and dehydration reactions.

Electrolyte-Dependent Electrosynthesis and Activity of Cobalt-Based Water Oxidation Catalysts

Abstract: Electrolysis of Co2+ in phosphate, methylphosphonate, and borate electrolytes effects the electrodeposition of an amorphous highly active water oxidation catalyst as a thin film on an inert anode. Electrodeposition of a catalytically competent species immediately follows oxidation of Co2+ to Co3+ in solution. Methylphosphonate and borate electrolytes support catalyst activity comparable to that observed for phosphate. Catalytic activity for O2 generation in aqueous solutions containing 0.5 M NaCl is retained for catalysts grown from phosphate electrolyte.