Effects of oxide platforms on the dynamics and reduction characteristics of hydrogen spillover.

The characteristics of hydrogen spillover on various metal oxides, involving the concurrent diffusion of protons (H) and electrons (e), were systematically studied by combining analytical techniques with kinetic analyses. H-temperature programmed reduction and X-ray absorption fine structure data showed that hydrogen spillover from Pt onto TiO and WO greatly decreased the temperatures at which Zn ions deposited on these remote metal oxides were reduced. In contrast, hydrogen spillover on MgO and CeO did not significantly affect the reduction of remote Zn.

Heteroatom doping enables hydrogen spillover via H/e diffusion pathways on a non-reducible metal oxide.

Hydrogen spillover, the simultaneous diffusion of protons (H) and electrons (e) is considered to be applicable to ubiquitous technologies related to hydrogen but limited to over reducible metal oxides. The present work demonstrates that a non-reducible MgO with heteroatom Al dopants (Al-MgO) allows hydrogen spillover in the same way as reducible metal oxides. Furthermore, a H storage capacity of this material owing to hydrogen spillover is more than three times greater than those of various standard metal oxides based on H transport channels within its bulk region.

Thermal Stability of High-Entropy Alloy Nanoparticles Evaluated by In Situ TEM Observations.

High-entropy alloy (HEA) nanoparticles (NPs) have attracted attention in several fields because of their fascinating properties. The high mechanical strength, good thermal stability, and superior corrosion resistance of HEAs, which are derived from their high configurational entropy, are attractive features. Herein, we investigated the thermal stability of FeCoNiCuPd HEA NPs on reduced graphene oxide via in situ transmission electron microscopy observations at elevated temperatures.

Specific Hydrogen Spillover Pathways Generated on Graphene Oxide Enabling the Formation of Non-Equilibrium Alloy Nanoparticles.

The phenomenon of hydrogen spillover is investigated as a means of realizing a hydrogen-based society for over half a century. Herein, a graphene oxide having a precisely tuned architecture via calcination in air to introduce ether groups onto basal planes along with carbon defects is reported. This material provides specific pathways for the spillover of atomic hydrogen and has practical applications with regard to the synthesis of non-equilibrium solid-solution alloy nanoparticles.

Surface Chemical Engineering of a Metal 3D-Printed Flow Reactor Using a Metal-Organic Framework for Liquid-Phase Catalytic H Production from Hydrogen Storage Materials.

The accurate positioning of metal-organic frameworks (MOFs) on the surface of other materials has opened up new possibilities for the development of multifunctional devices. We propose here a postfunctionalization approach for three-dimensional (3D)-printed metallic catalytic flow reactors based on MOFs. The Cu-based reactors were immersed into an acid solution containing an organic linker for the synthesis of MOFs, where Cu ions dissolved in situ were assembled to form MOF crystals on the surface of the reactor.

Sub-nanometric High-Entropy Alloy Cluster: Hydrogen Spillover Driven Synthesis on CeO and Structural Reversibility.

High-entropy alloy (HEA) nanoparticles (NPs) have attracted significant attention as promising catalysts owing to the various unique synergistic effects originating from the nanometer-scale, near-equimolar mixing of five or more components to produce single-phase solid solutions. However, the study of sub-nanometer HEA clusters having sizes of less than 1 nm remains incomplete despite the possibility of novel functions related to borderline molecular states with discrete quantum energy levels. The present work demonstrates the synthesis of CeO nanorods (CeO-NRs) on which sub-nanometer CoNiCuZnPd HEA clusters were formed with the aid of a pronounced hydrogen spillover effect on readily reducible CeO (110) facets.

Improved Low-Temperature Hydrogen Production from Aqueous Methanol Based on Synergism between Cationic Pt and Interfacial Basic LaO.

Aqueous phase reforming of methanol (APRM) is simple, inexpensive and provides a high hydrogen gravimetric density of 18.8 wt. %, and so is superior to traditional gas-phase reactions performed at relatively high temperatures.

Lewis acid-triggered photocatalytic hydrogen peroxide production in an aluminum-based metal-organic framework.

Al-MIL-101-NH, which was previously regarded as being inactive as a photocatalyst, produces hydrogen peroxide (HO) O reduction under visible-light irradiation, accompanied by efficient suppression of undesired HO decomposition. The low-coordination Lewis acid sites in trimetric Al-oxo clusters are crucial for the electron transfer to O.

Revealing hydrogen spillover pathways in reducible metal oxides.

Hydrogen spillover, the migration of dissociated hydrogen atoms from noble metals to their support materials, is a ubiquitous phenomenon and is widely utilized in heterogeneous catalysis and hydrogen storage materials. However, in-depth understanding of the migration of spilled hydrogen over different types of supports is still lacking. Herein, hydrogen spillover in typical reducible metal oxides, such as TiO, CeO, and WO, was elucidated by combining systematic characterization methods involving various techniques, kinetic analysis, and density functional theory calculations.

Overcoming Acidic HO/Fe(II/III) Redox-Induced Low HO Utilization Efficiency by Carbon Quantum Dots Fenton-like Catalysis.

Fenton reaction has important implications in biology- and environment-related remediation. Hydroxyl radicals (OH) and hydroxide (OH) were formed by a reaction between Fe(II) and hydrogen peroxide (HO). The acidic HO/Fe(II/III) redox-induced low HO utilization efficiency is the bottleneck of Fenton reaction.

Defect Engineering of Pt/TiO Photocatalysts via Reduction Treatment Assisted by Hydrogen Spillover.

Defect engineering of metal oxides is a facile and promising strategy to improve their photocatalytic activity. In the present study, Pt/TiO was prepared by a reduction treatment assisted by hydrogen spillover to pure rutile, anatase, and brookite and was subsequently used for hydrogen production from an aqueous methanol solution. With increasing reduction temperature, the photocatalytic activity of the rutile Pt/TiO increased substantially, whereas the activity of anatase Pt/TiO decreased and that of brookite Pt/TiO was independent of the treatment temperature.

Hydrogen spillover-driven synthesis of high-entropy alloy nanoparticles as a robust catalyst for CO hydrogenation.

High-entropy alloys (HEAs) have been intensively pursued as potentially advanced materials because of their exceptional properties. However, the facile fabrication of nanometer-sized HEAs over conventional catalyst supports remains challenging, and the design of rational synthetic protocols would permit the development of innovative catalysts with a wide range of potential compositions. Herein, we demonstrate that titanium dioxide (TiO) is a promising platform for the low-temperature synthesis of supported CoNiCuRuPd HEA nanoparticles (NPs) at 400 °C.

How the Morphology of NiO-Decorated CeO Nanostructures Affects Catalytic Properties in CO Methanation.

Effects of morphology and exposed crystal planes of NiO-decorated CeO (NiCeO) nanostructured catalysts on activity during CO methanation were examined, using nanorod (NR), nanocube (NC), and nanooctahedron (NO) structures. The NiCeO nanorods (NiCeO-NR) showed superior activity to NiCeO-NC and NiCeO-NO along with excellent selectivity for CH. This material also demonstrated exceptional durability, with no significant loss of catalytic activity or structural change after use.

Modification of Ti-doped Hematite Photoanode with Quasi-molecular Cocatalyst: A Comparison of Improvement Mechanism Between Non-noble and Noble Metals.

Loading of molecular catalyst on the surface of semiconductors is an attractive way to boost the water oxidation activity. As active sites, molecular water oxidation cocatalysts show increasing attraction and application possibility. In order to compare the advantages between molecular catalysts with non-noble and noble metals, the loading of the Fe(salen) and Ru(salen) as cocatalyst precursors on the surface of Ti-Fe O was investigated Quasi-Fe(salen) and Ru(salen) improved the photocurrent density by 1.

Experimental and computational study on roles of WO promoting strong metal support promoter interaction in Pt catalysts during glycerol hydrogenolysis.

Biodiesel is of high interest due to increased demand for energy with the concern regarding more sustainable production processes. However, an inevitable by-product is glycerol. Hence, the conversion of this by-product to higher-value chemicals, especially 1,3-propanediol (1,3-PDO) via glycerol hydrogenolysis reaction, is one of the most effective pathways towards a profitable process.

Synthesis of small Ni-core-Au-shell catalytic nanoparticles on TiO by galvanic replacement reaction.

We report the first preparation of small gold-nickel (AuNi) bimetallic nanoparticles (<5 nm) supported on titania by the method of galvanic replacement reaction (GRR), evidenced by the replacement of Ni atoms by Au atoms according to the stoichiometry of the reaction. We showed that this preparation method allowed not only the control of the gold and nickel contents in the samples, but also the formation of small bimetallic nanoparticles with strained core-shell structures, as revealed by aberration-corrected scanning transmission electron microscopy in combination with energy-dispersive X-ray spectroscopy mapping. The catalytic characterization by the probe reaction of semi-hydrogenation of butadiene showed that the resulting nickel-based nanocatalysts containing a small amount of gold exhibited higher selectivity to butenes than pure nickel catalysts and a high level of activity, closer to that of pure nickel catalysts than to that of pure gold catalysts.

Hybrid phase 1T/2H-MoS with controllable 1T concentration and its promoted hydrogen evolution reaction.

MoS2 has been investigated as a low-cost alternative to Pt in the electrochemical hydrogen evolution reaction. One of the promising methods to further activate MoS2 is phase engineering. MoS2 generally exhibits two kinds of crystalline phases: hexagonal 2H phase and octahedral 1T phase.

Metal-organic framework-based nanomaterials for photocatalytic hydrogen peroxide production.

As an environmentally friendly and renewable energy source, hydrogen peroxide (H2O2) could be produced photocatalytically through selective two-electron reduction of O2 using effective photocatalysts. Metal organic frameworks (MOFs), as hybrid porous materials consisting of organic linkers and metal oxide clusters, have aroused great interest in the design of effective catalysts for photocatalysis under visible light irradiation due to their unique properties, such as large surface area, good chemical stability, and diverse and tunable chemical components. In this perspective, we highlight our recent progress in the application of various MOF-based nanomaterials for photocatalytic H2O2 production from the selective two-electron reduction of O2 in a single-phase system (acetonitrile) and two-phase system (water/benzyl alcohol).

Diesel Soot Combustion over Mn O Catalysts with Different Morphologies: Elucidating the Role of Active Oxygen Species in Soot Combustion.

Catalytic diesel soot combustion was examined using a series of Mn O catalysts with different morphologies, including plate, prism, hollow spheres and powders. The plate-shaped Mn O (Mn O -plate) exhibited superior carbon soot combustion activity compared to the prism-shaped, hollow-structured and powdery Mn O under both tight and loose contact modes at soot combustion temperatures (T ) of 327 °C and 457 °C, respectively. Comprehensive characterization studies using scanning electron microscopy, scanning transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction and oxygen release measurements, revealed that the improved activity of Mn O -plate was mainly attributed to the high oxygen release rate of surface-adsorbed active oxygen species, which originated from oxygen vacancy sites introduced during the catalyst preparation, rather than specific surface-exposed planes.

Functionalized mesoporous SBA-15 silica: recent trends and catalytic applications.

The development of advanced materials for heterogeneous catalytic applications requires fine control over the synthesis and structural parameters of the active site. Mesoporous silica materials have attracted increasing attention to be considered as an important class of nanostructured support materials in heterogeneous catalysis. Their large surface area, well-defined porous architecture and ability to incorporate metal atoms within the mesopores lead them to be a promising support material for designing a variety of different catalysts.

Synthesis of a binary alloy nanoparticle catalyst with an immiscible combination of Rh and Cu assisted by hydrogen spillover on a TiO support.

This work demonstrated the use of TiO as a promising platform for the synthesis of non-equilibrium RhCu binary alloy nanoparticles (NPs). These metals are regarded as immiscible based on their phase diagram but form NPs with the aid of the significant hydrogen spillover on TiO with concurrent proton-electron transfer. The resulting RhCu/TiO exhibited 2.

Construction of Hybrid MoS Phase Coupled with SiC Heterojunctions with Promoted Photocatalytic Activity for 4-Nitrophenol Degradation.

Phase engineering has been recognized as a promising method for boosting the catalytic activity of molybdenum sulfide (MoS) in the field of electrocatalysts and photocatalysts. The metallic 1T-MoS exhibits much higher catalytic activity than natural semiconducting 2H-MoS but suffers from harsh synthetic conditions and metastable physical/chemical properties. The hybrid 1T/2H phase MoS shows higher catalytic activity than the 2H-MoS and exhibits better stability than the 1T-MoS, which is more favorable than the 2H-MoS in the photocatalytic reactions.

CoO-decorated CeO heterostructures: effects of morphology on their catalytic properties in diesel soot combustion.

The effect of the morphology, which exposes different crystal planes, on the physicochemical properties and catalytic activity in diesel carbon soot oxidation was studied using CoOx-decorated CeO2 (CoCeO2) heterostructured catalysts, such as nanorods (NRs), nanocubes (NCs), and nanoparticles (NPs). The CoOx/CeO2 nanorods (CoCeO2-NR) showed superior carbon soot combustion activity at lower temperatures to CoCeO2-NCs and CoCeO2-NPs under both tight and loose contact modes with soot combustion temperatures (T50) of 321 and 494 °C, respectively. A comprehensive analysis by means of X-ray diffraction, Raman spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, in situ X-ray absorption fine structure, temperature-programmed reduction, oxygen storage/release measurements, and density functional theory calculations revealed that the improved activity of CoCeO2-NRs is mainly ascribed to the high oxygen release rate and strong redox capability of the supported Co species, with complete reversibility.

Design of Advanced Functional Materials Using Nanoporous Single-Site Photocatalysts.

Nanoporous silica solids can offer opportunities for hosting photocatalytic components such as various tetra-coordinated transition metal ions to form systems referred to as "single-site photocatalysts". Under UV/visible-light irradiation, they form charge transfer excited states, which exhibit a localized charge separation and thus behave differently from those of bulk semiconductor photocatalysts exemplified by TiO . This account presents an overview of the design of advanced functional materials based on the unique photo-excited mechanisms of single-site photocatalysts.