Oxygen evolution activity of nickel-based phosphates and effects of their electronic orbitals.

Metal phosphate-type compounds have been utilized in diverse applications, and their distinctive chemical properties have recently opened avenues for their use as catalysts. Metal phosphates have previously demonstrated significant electrocatalytic activity for the anodic oxygen evolution reaction (OER) in electrochemical water splitting. However, the critical factors influencing OER electrocatalysis on Ni-based phosphates have been insufficiently explored.

LaSrFeO Perovskite Oxide Nanoparticles for Low-Temperature Aerobic Oxidation of Isobutane to -Butyl Alcohol.

The development of reusable solid catalysts based on naturally abundant metal elements for the liquid-phase selective oxidation of light alkanes under mild conditions to obtain desired oxygenated products, such as alcohols and carbonyl compounds, remains a challenge. In this study, various perovskite oxide nanoparticles were synthesized by a sol-gel method using aspartic acid, and the effects of A- and B-site metal cations on the liquid-phase oxidation of isobutane to -butyl alcohol with molecular oxygen as the sole oxidant were investigated. Iron-based perovskite oxides containing Fe such as BaFeO, SrFeO, and LaSrFeO exhibited catalytic performance superior to those of other Fe- and Fe-based iron oxides and Mn-, Ni-, and Co-based perovskite oxides.

Synthesis and catalytic application of nanostructured metal oxides and phosphates.

The design and development of new high-performance catalysts is one of the most important and challenging issues to achieve sustainable chemical and energy production. This Feature Article describes the synthesis of nanostructured metal oxides and phosphates mainly based on earth-abundant metals and their thermocatalytic application to selective oxidation and acid-base reactions. A simple and versatile methodology for the control of nanostructures based on crystalline complex oxides and phosphates with diverse structures and compositions is proposed as another approach to catalyst design.

Tuning the Selectivity of Catalytic Nitrile Hydrogenation with Phase-Controlled Co Nanoparticles Prepared by Hydrosilane-Assisted Method.

Cobalt (Co) is a promising candidate to replace noble metals in the hydrogenation process, which is widely employed in the chemical industry. Although the catalytic performance for this reaction has been considered to be significantly dependent on the Co crystal phase, no satisfactory systematic studies have been conducted, because it is difficult to synthesize metal nanoparticles that have different crystalline structures with similar sizes. Here we report a new method for the synthesis of cobalt nanoparticles using hydrosilane as a reducing agent (hydrosilane-assisted method).

Air-Stable Ni Catalysts Prepared by Liquid-Phase Reduction Using Hydrosilanes for Reactions with Hydrogen.

The liquid-phase reduction method for the preparation of metal nanoparticles (NPs) by the reduction of metal salts or metal complexes in a solvent with a reducing agent is widely used to prepare Ni NPs that exhibit high catalytic activity in various organic transformations. Intensive research has been conducted on control of the morphology and size of Ni NPs by the addition of polymers and long-chain compounds as protective agents; however, these agents typically cause a decrease in catalytic activity. Here, we report on the preparation of Ni NPs using hydrosilane (Ni-Si) as a reducing agent and a size-controlling agent.

A redox-active inorganic crown ether based on a polyoxometalate capsule.

Cation-uptake has been long researched as an important topic in materials science. Herein we focus on a molecular crystal composed of a charge-neutral polyoxometalate (POM) capsule [MoFeO(HO)(CHCO)] encapsulating a Keggin-type phosphododecamolybdate anion [α-PMoO]. Cation-coupled electron-transfer reaction occurs by treating the molecular crystal in an aqueous solution containing CsCl and ascorbic acid as a reducing reagent.

Nanosized Ti-Based Perovskite Oxides as Acid-Base Bifunctional Catalysts for Cyanosilylation of Carbonyl Compounds.

The development of effective solid acid-base bifunctional catalysts remains a challenge because of the difficulty associated with designing and controlling their active sites. In the present study, highly pure perovskite oxide nanoparticles with -transition-metal cations such as Ti, Zr, and Nb as -site elements were successfully synthesized by a sol-gel method using dicarboxylic acids. Moreover, the specific surface area of SrTiO was increased to 46 m g by a simple procedure of changing the atmosphere from N to air during calcination of an amorphous precursor.

Synthesis and Aerobic Oxidation Catalysis of Mesoporous Todorokite-Type Manganese Oxide Nanoparticles by Crystallization of Precursors.

The pursuit of a high surface area while maintaining high catalytic performance remains a challenge due to a trade-off relationship between these two features in some cases. In this study, mesoporous todorokite-type manganese oxide (OMS-1) nanoparticles with high specific surface areas were synthesized in one step by a new synthesis approach involving crystallization (i.e.

Base-Assisted Aerobic C-H Oxidation of Alkylarenes with a Murdochite-Type Oxide MgMnO Nanoparticle Catalyst.

Heterogeneously catalyzed aerobic oxidative C-H functionalization under mild conditions is a chemical process to obtain desired oxygenated products directly. Nanosized murdochite-type oxide MgMnO (MgMnO-MA) was successfully synthesized by the sol-gel method using malic acid. The specific surface area reached up to 104 m g, which is about 7 times higher than those (2-15 m g) of MgMnO synthesized by previously reported methods.

Effects of ruthenium hydride species on primary amine synthesis by direct amination of alcohols over a heterogeneous Ru catalyst.

Heterogeneously catalysed synthesis of primary amines by direct amination of alcohols with ammonia has long been an elusive goal. In contrast to reported Ru-based catalytic systems, we report that Ru-MgO/TiO acts as an effective heterogeneous catalyst for the direct amination of a variety of alcohols to primary amines at low temperatures of 100 °C without the introduction of H gas. The present system could be applied to a variety of alcohols and provides an efficient synthetic route for 2,5-bis(aminomethyl)furan (BAMF), an attention-getting biomonomer.

Electronic Effect in a Ruthenium Catalyst Designed in Nanoporous N-Functionalized Carbon for Efficient Hydrogenation of Heteroarenes.

Active metal catalysts are the key in chemical industry for sustainable production of multitude of chemical resources. Here, we report a new ruthenium (Ru) composite with a synergistically controlled nanostructure and electronic properties as a highly efficient hydrogenation catalyst which comprises stable small Ru nanoparticles (mean particle size, 0.9 nm) in situ generated into a nanoporous N-functionalized carbon with high surface area ( 650 m g) and has strong electron-donating power of Ru sites of nanoparticles.

One-pot reductive amination of carbonyl compounds with nitro compounds over a Ni/NiO composite.

Easily prepared Ni/NiO acts as a heterogeneous catalyst for the one-pot reductive amination of carbonyl compounds with nitroarenes to afford secondary amines with H as a hydride source. This catalytic system does not require a special technique to avoid air-exposure, in contrast to the common heterogeneous Ni catalysts.

Template-Free Synthesis of Mesoporous β-MnO Nanoparticles: Structure, Formation Mechanism, and Catalytic Properties.

Mesoporous β-MnO nanoparticles were synthesized by a template-free low-temperature crystallization of Mn precursors (low-crystallinity layer-type Mn oxide, -distorted H-birnessite) produced by the reaction of MnO and Mn. The Mn starting materials, pH of the reaction solution, and calcination temperatures significantly affect the crystal structure, surface area, porous structure, and morphology of the manganese oxides formed. The pH conditions during the precipitation of Mn precursors are important for controlling the morphology and porous structure of β-MnO.

One-pot aerobic oxidative sulfonamidation of aromatic thiols with ammonia by a dual-functional β-MnO nanocatalyst.

High-surface-area β-MnO2 (β-MnO2-HS) nanoparticles could act as effective heterogeneous catalysts for the one-pot oxidative sulfonamidation of various aromatic and heteroaromatic thiols to the corresponding sulfonamides using molecular oxygen (O2) and ammonia (NH3) as respective oxygen and nitrogen sources, without the need for any additives.

Ambient-temperature oxidative coupling of methane in an electric field by a cerium phosphate nanorod catalyst.

CePO4 nanorods with uniform surface Ce sites could work as a durable catalyst and showed the highest C2 yield of 18% in an electric field without the need for external heating, which was comparable to that reported for high-performance catalysts at high temperature (>900 K).

Effect of MnO Crystal Structure on Aerobic Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid.

Aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) as a bioplastics monomer is efficiently promoted by a simple system based on a nonprecious-metal catalyst of MnO and NaHCO. Kinetic studies indicate that the oxidation of 5-formyl-2-furancarboxylic acid (FFCA) to FDCA is the slowest step for the aerobic oxidation of HMF to FDCA over activated MnO. We demonstrate through combined computational and experimental studies that HMF oxidation to FDCA is largely dependent on the MnO crystal structure.

A high performance catalyst of shape-specific ruthenium nanoparticles for production of primary amines by reductive amination of carbonyl compounds.

The creation of metal catalysts with highly active surfaces is pivotal to meeting the strong economic demand of the chemical industry. Specific flat-shaped pristine fcc ruthenium nanoparticles having a large fraction of atomically active {111} facets exposed on their flat surfaces have been developed that act as a highly selective and reusable heterogeneous catalyst for the production of various primary amines at exceedingly high reaction rates by the low temperature reductive amination of carbonyl compounds. The high performance of the catalyst is attributed to the large fraction of metallic Ru serving as active sites with weak electron donating ability that prevail on the surface exposed {111} facets of flat-shaped fcc Ru nanoparticles.

Heterogeneously Catalyzed Aerobic Oxidation of Sulfides with a BaRuO Nanoperovskite.

A rhombohedral BaRuO nanoperovskite, which was synthesized by the sol-gel method using malic acid, could act as an efficient heterogeneous catalyst for the selective oxidation of various aromatic and aliphatic sulfides with molecular oxygen as the sole oxidant. BaRuO showed much higher catalytic activities than other catalysts, including ruthenium-based perovskite oxides, under mild reaction conditions. The catalyst could be recovered by simple filtration and reused several times without obvious loss of its high catalytic performance.

Liquid-phase oxidation of alkanes with molecular oxygen catalyzed by high valent iron-based perovskite.

Hexagonal BaFeO3-δ containing high valent iron species acted as an efficient heterogeneous catalyst for the aerobic oxidation of alkanes without the need for additives. The activity of BaFeO3-δ was much higher than that of typical Fe3+/Fe2+-containing iron oxide-based catalysts, and the recovered catalyst could be reused without significant loss of catalytic performance.

Electronic Effect of Ruthenium Nanoparticles on Efficient Reductive Amination of Carbonyl Compounds.

Highly selective synthesis of primary amines over heterogeneous catalysts is still a challenge for the chemical industry. Ruthenium nanoparticles supported on NbO act as a highly selective and reusable heterogeneous catalyst for the low-temperature reductive amination of various carbonyl compounds that contain reduction-sensitive functional groups such as heterocycles and halogens with NH and H and prevent the formation of secondary amines and undesired hydrogenated byproducts. The selective catalysis of these materials is likely attributable to the weak electron-donating capability of Ru particles on the NbO surface.

Preparation of Mesoporous Basic Oxides through Assembly of Monodispersed Mg-Al Layered Double Hydroxide Nanoparticles.

Mesoporous basic Mg-Al mixed metal oxides (MMOs) with a high surface area and large pore size have been prepared through the assembly of monodispersed layered double hydroxide nanoparticles (LDHNPs) with block copolymer templates. The particle sizes of the LDHNPs were mainly controlled by varying the concentration of tris(hydroxymethyl)aminomethane (THAM), which was used as a surface stabilizing agent. LDHNPs and micelles of a block copolymer (Pluronic F127) were assembled to form a composite.

A bifunctional cerium phosphate catalyst for chemoselective acetalization.

Acid-base solid catalysts synthesized with structurally controlled uniform active sites can lead to unique catalysis. In this study, a CePO catalyst was synthesized using a hydrothermal method and found to exhibit high catalytic performance for the chemoselective acetalization of 5-hydroxymethylfurfural with alcohols, in sharp contrast to other homogeneous and heterogeneous acid and/or base catalysts. In the presence of CePO, various combinations of carbonyl compounds and alcohols are efficiently converted into the corresponding acetal derivatives in good to excellent yields.

Amino Acid-Aided Synthesis of a Hexagonal SrMnO Nanoperovskite Catalyst for Aerobic Oxidation.

A simple and efficient synthetic method for preparing high-surface-area perovskites was investigated by focusing on the importance of the formation of an amorphous precursor. Hexagonal SrMnO with high surface area was successfully synthesized by simple calcination of the amorphous precursor prepared using and metal instead of metal , without pH adjustment. The specific surface area reached up to ca.