The surface science of titanium dioxide

Polymeric graphitic carbon nitride materials (for simplicity: g-C(3)N(4)) have attracted much attention in recent years because of their similarity to graphene. They are composed of C, N, and some minor H content only. In contrast to graphenes, g-C(3)N(4) is a medium-bandgap semiconductor and in that role an effective photocatalyst and chemical catalyst for a broad variety of reactions. In this Review, we describe the "polymer chemistry" of this structure, how band positions and bandgap can be varied by doping and copolymerization, and how the organic solid can be textured to make it an effective heterogenous catalyst. g-C(3)N(4) and its modifications have a high thermal and chemical stability and can catalyze a number of "dream reactions", such as photochemical splitting of water, mild and selective oxidation reactions, and--as a coactive catalytic support--superactive hydrogenation reactions. As carbon nitride is metal-free as such, it also tolerates functional groups and is therefore suited for multipurpose applications in biomass conversion and sustainable chemistry.

Polymeric Graphitic Carbon Nitride as a Heterogeneous Organocatalyst: From Photochemistry to Multipurpose Catalysis to Sustainable Chemistry

Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal–support interaction, and metal–reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results o...

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles.

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

The Interaction of Water with Solid Surfaces: Fundamental Aspects Revisited

Silver–tungsten oxide wafer-like nanoarchitectures were prepared for the first time for selective epoxidation of a wide range of alkenes to their corresponding epoxides with high yield. The wafer-like nanostructure provides sufficient contact between the substrate/catalyst and overcomes the steric influence of the bulkier substrates. The influence of various reaction parameters, such as temperature, substrate to oxidant molar ratio, reaction time, and so forth, were investigated in detail. The catalyst was characterized by XRD, XPS, EXAFS, ICP-AES, RAMAN, SEM, and TEM. Raman studies prove that the formation of peroxo tungsten species is responsible for epoxiation reaction. High stability and recyclability of the Ag–W catalyst is also observed under the investigated conditions.

Fabrication of Silver–Tungsten Wafer-like Nanoarchitectures for Selective Epoxidation of Alkenes

Diamondoids were synthesized by dielectric barrier discharges in supercritical xenon containing dissolved adamantane, which served as a precursor. The synthesis of diamantane was confirmed by gas chromatography mass spectrometry measurements, in addition to energy-dispersive X-ray spectroscopy and micro-Raman spectroscopy measurements. Moreover, the possible synthesis of two higher-order diamondoids, pentamantane and decamantane, with molecular weights of 330 and 456, respectively, is indicated from the selective ion monitoring mode. The largest production yield was obtained in the vicinity of the critical point.

http://iopscience.iop.org/article/10.1143/JJAP.50.030207/pdf

Synthesis of Diamondoids by Supercritical Xenon Discharge Plasma

A novel and simple method for the synthesis of aromatic linear polyester amides has been developed by the carbonylation–polycondensation reaction of aromatic diiodides and aminohydroxy compounds in the presence of ImmPd-IL@SBA-15 catalytic system. Polyester amides with moderate intrinsic viscosity were synthesized in excellent yields using the ImmPd-IL@SBA-15 catalyst and represents efficient heterogeneous and phosphine-free approach for the synthesis of various linear polyester amide derivatives. The ImmPd-IL@SBA-15 catalyst solves the basic problem of catalyst recovery and furnishes good to excellent yield of desired product within short reaction time. The recycled catalyst was characterized using the XPS and TEM analysis. The catalyst was recycled four times without significant loss in activity. Catalytic polyester amide synthesis

Synthesis of Polyester Amide by Carbonylation–Polycondensation Reaction Using Immobilized Palladium Metal Containing Ionic Liquid on SBA-15 as a Phosphine-Free Catalytic System

The well-known cumene process via an explosive cumene hydroperoxide intermediate in liquid phase currently employed for phenol production is energy-intensive and not environmentally friendly. Therefore, there is a demand for an alternative single-step gas-phase catalysis process. According to the conventional catalysis concept, selective oxidation reactions are promoted by redox catalysts and not by acid–base catalysts. In general, alkali and alkaline earth metal ions cannot activate each of benzene, O2, and N2O when they adsorb separately. However, we observed an unprecedented catalysis of single alkali and alkaline earth metal ion sites incorporated into zeolite pores for the selective oxidation of benzene to phenol with N2O and O2 + NH3, thereby providing a single-site catalytic platform with high selectivity. Among alkali and alkaline earth metal ions, single Cs+ and Rb+ sites with ion diameters of >300 pm in the pores of β-zeolites exhibited remarkable selectivity for benzene C–H activation to phenol...

Confined Single Alkali Metal Ion Platform in a Zeolite Pore for Concerted Benzene C–H Activation to Phenol Catalysis

Supported metal nanoparticles hold great promise in heterogeneous catalysis as active and reusable catalysts for various organic transformations. Preparation methods of metal nanoparticles with excellent control over size, shape, and morphology on supports has significantly advanced to improve the performances of the resulting catalysts. Here, we aim to discuss the development of supported metal nanoparticles on mesoporous silica SBA-15 in the presence of immobilized ionic liquids mostly based on examples from the previously reported results. This review highlights the preparation methods for size-controlled syntheses and the immobilization of metal nanoparticles on solid supports, especially SBA-15 by various techniques.

Takehiko Sasaki

Papers

Fabrication of Silver–Tungsten Wafer-like Nanoarchitectures for Selective Epoxidation of Alkenes

Synthesis of Diamondoids by Supercritical Xenon Discharge Plasma

Synthesis of Polyester Amide by Carbonylation–Polycondensation Reaction Using Immobilized Palladium Metal Containing Ionic Liquid on SBA-15 as a Phosphine-Free Catalytic System

Confined Single Alkali Metal Ion Platform in a Zeolite Pore for Concerted Benzene C–H Activation to Phenol Catalysis

Metal Nanoparticles Syntheses on Ionic Liquids Functionalized Mesoporous Silica SBA‐15