There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Jenny Schneider,*,† Masaya Matsuoka,‡ Masato Takeuchi,‡ Jinlong Zhang, Yu Horiuchi,‡ Masakazu Anpo,‡ and Detlef W. Bahnemann*,† †Institut fur Technische Chemie, Leibniz Universitaẗ Hannover, Callinstrasse 3, D-30167 Hannover, Germany ‡Faculty of Engineering, Osaka Prefecture University, 1 Gakuen-cho, Sakai Osaka 599-8531, Japan Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China

Understanding TiO2 photocatalysis: mechanisms and materials.

Metal–organic frameworks (MOFs), also known as porous coordination polymers (PCPs), synthesized by assembling metal ions with organic ligands have recently emerged as a new class of crystalline porous materials. The amenability to design as well as fine-tunable and uniform pore structures makes them promising materials for a variety of applications. Controllable integration of MOFs and functional materials is leading to the creation of new multifunctional composites/hybrids, which exhibit new properties that are superior to those of the individual components through the collective behavior of the functional units. This is a rapidly developing interdisciplinary research area. This review provides an overview of the significant advances in the development of diverse MOF composites reported till now with special emphases on the synergistic effects and applications of the composites. The most widely used and successful strategies for composite synthesis are also presented.

Metal–organic framework composites

Metal-organic frameworks (MOFs) are an emerging class of porous materials with potential applications in gas storage, separations, catalysis, and chemical sensing. Despite numerous advantages, applications of many MOFs are ultimately limited by their stability under harsh conditions. Herein, the recent advances in the field of stable MOFs, covering the fundamental mechanisms of MOF stability, design, and synthesis of stable MOF architectures, and their latest applications are reviewed. First, key factors that affect MOF stability under certain chemical environments are introduced to guide the design of robust structures. This is followed by a short review of synthetic strategies of stable MOFs including modulated synthesis and postsynthetic modifications. Based on the fundamentals of MOF stability, stable MOFs are classified into two categories: high-valency metal-carboxylate frameworks and low-valency metal-azolate frameworks. Along this line, some representative stable MOFs are introduced, their structures are described, and their properties are briefly discussed. The expanded applications of stable MOFs in Lewis/Bronsted acid catalysis, redox catalysis, photocatalysis, electrocatalysis, gas storage, and sensing are highlighted. Overall, this review is expected to guide the design of stable MOFs by providing insights into existing structures, which could lead to the discovery and development of more advanced functional materials.

Stable Metal-Organic Frameworks: Design, Synthesis, and Applications.

Note: Times Cited: 875 Reference EPFL-ARTICLE-206025doi:10.1021/cr0501846View record in Web of Science URL: ://WOS:000249839900009 Record created on 2015-03-03, modified on 2017-05-12

Complex Hydrides for Hydrogen Storage

In this study, operando Ce K-edge XANES measurements of CeO2-supported Ni (Ni/CeO2) catalysts for chemical looping dry reforming of methane (CLDRM) were performed. Low-loading Ni/CeO2 was effective for selectively promoting the partial oxidation of CH4 and suppressing coke deposition. Operando XANES measurements confirmed the redox state of Ce oxide in CLDRM and revealed that the reoxidation of reduced Ce oxide during CO2 reduction was faster than the reduction of Ce oxide during CH4 oxidation. Operando Ce K-edge XANES measurements of CeO2-supported Ni (Ni/CeO2) catalysts for chemical looping dry reforming of methane (CLDRM) were performed. Low-loading Ni/CeO2 was effective for selectively promoting the partial oxidation of CH4. Operando XANES measurements revealed that the reoxidation of reduced Ce oxide during CO2 reduction was faster than the reduction of Ce oxide during CH4 oxidation. 

Operando Ce K-edge XANES study of low-loading Ni/CeO2 in chemical looping dry reforming of methane

Dimethylacetamide-stabilized ruthenium nanoparticles for catalysing α-alkylations of amides with alcohols.

Perovskite oxides comprise an important class of materials, and some of their applications depend on the surface reactivity characteristics. We calculated, using density functional theory, the surface O vacancy formation energy (EOvac) for perovskite-structure oxides, with a transition metal (Ti–Fe) as the B-site cation, to estimate the catalytic reactivity of perovskite oxides. The EOvac value correlated well with the band gap and bulk formation energy, which is a trend also found in other oxides. A low EOvac value, which is expected to result in higher catalytic activity via the Mars–van Krevelen mechanism, was found in metallic perovskites such as CaCoO3, BaFeO3, and SrFeO3. On the other hand, titanates had high EOvac values, typically exceeding 4 eV/atom, suggesting that these materials are less reactive when O vacancy formation is involved in the reaction mechanism.

Trends in Surface Oxygen Formation Energy in Perovskite Oxides

In this chapter, the application of metal-organic framework (MOF) as a visible light–responsive photocatalyst for water-splitting reaction will be reviewed. The organic linker moieties as well as inorganic metal oxide clusters within MOF can act as the visible light–harvesting units where excited electrons and holes are produced. It will be demonstrated that the H2 evolution reaction on MOF photocatalysts are initiated by the photoexcitation of organic linker moieties and following electron transfer to metal oxides, that is the dye-sensitizing mechanism. On the other hand, the O2 evolution reaction on MOF is initiated by the water oxidation by the photoformed holes produced on metal oxide moieties under visible light irradiation.

The design and development of MOF photocatalysts and their applications for water-splitting reaction

Abstract The catalytic combustion of methane at a low temperature is becoming increasingly key to controlling unburned CH 4 emissions from natural gas vehicles and power plants, although the low activity of benchmark platinum-group-metal catalysts hinders its broad application. Based on automated reaction route mapping, we explore main-group elements catalysts containing Si and Al for low-temperature CH 4 combustion with ozone. Computational screening of the active site predicts that strong Brønsted acid sites are promising for methane combustion. We experimentally demonstrate that catalysts containing strong Bronsted acid sites exhibit improved CH 4 conversion at 250 °C, correlating with the theoretical predictions. The main-group catalyst (proton-type beta zeolite) delivered a reaction rate that is 442 times higher than that of a benchmark catalyst (5 wt% Pd-loaded Al 2 O 3 ) at 190 °C and exhibits higher tolerance to steam and SO 2 . Our strategy demonstrates the rational design of earth-abundant catalysts based on automated reaction route mapping. 

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Takashi Toyao

Papers

Operando Ce K-edge XANES study of low-loading Ni/CeO2 in chemical looping dry reforming of methane

Dimethylacetamide-stabilized ruthenium nanoparticles for catalysing α-alkylations of amides with alcohols.

Trends in Surface Oxygen Formation Energy in Perovskite Oxides

The design and development of MOF photocatalysts and their applications for water-splitting reaction

Designing main-group catalysts for low-temperature methane combustion by ozone