Zur Kristallstruktur von Cu2M(BO3)O2 (M = Fe3+, Ga3+)

The Crystal Structure of Cu₂M(BO₃)O₂ (M = Fe³⁺, Ga³⁺) Single Crystals of the compounds Cu₂M(BO₃)O₂ (M = Fe³⁺ (I), Ga³⁺ (II)) were obtained by a B₂O₃ flux-technique. They crystallize in a monoclinic distorted variant of a Ludwigite structure with a partly ordered metal distribution. X-ray investigations on single crystals led to the space group C–P2₁/c (No. 14); I: a = 3.108(1); b = 12.003(1); c = 9.459(3) Å; b? = 96.66(3)°; Z = 4 and II: a = 3.1146(2); b = 11.921(3); c = 9.477(2) Å; b? = 97.91(2)°; Z = 4. All metal-sites are distorted octahedraly coordinated by oxygen-ions. The structure contains isolated planar BO₃-units and oxygen which is not coordinated to boron.     

Calorimetric Characterization of Surface Reactivity of Supported Ga2O3 Catalysts

The surface properties of supported gallium oxide catalysts prepared by impregnation of various supports (γ-Al₂O₃, SiO₂, TiO₂, ZrO₂) were investigated by adsorption microcalorimetry, using ammonia and water as probe molecules. In the case of acidic supports (γ-Al₂O₃, ZrO₂, TiO₂), the acidic character of supported gallium catalysts always decreased in comparison with gallium-free supports; on very weakly acidic SiO₂, new acidic centers were created when depositing Ga₂O₃. The addition of gallium oxide decreased the hydrophilic properties of alumina, titania and zirconia, but increased the amount of water adsorbed on silica. The catalytic performances in the selective catalytic reduction of NO by C₂H₄ in excess oxygenwere in the order Ga/Al₂O₃>Ga/TiO₂>Ga/ZrO₂>>Ga/SiO₂. This order is more related to the quality of the dispersion of Ga₂O₃ on the support than to the global acidity of the solids. This revised version was published online in July 2006 with corrections to the Cover Date.     

ACYLATION OF AROMATIC COMPOUNDS USING MOISTURE INSENSITIVE MESOPOROUS Si-MCM-41 SUPPORTED Ga2O3 CATALYST

ABSTRACT

Mesoporous Si-MCM-41 supported Ga₂O₃ is a highly active catalyst for the acylation of aromatic compounds with different acyl chlorides. Moreover, this catalyst is not deactivated by water and hence does not require moisture-free reaction conditions.     

Platinum‐Promoted Ga/Al2O3 as Highly Active,Selective, and Stable Catalyst for the Dehydrogenation of Propane

A novel catalyst material for the selective dehydrogenation of propane is presented. The catalyst consists of 1000 ppm Pt, 3 wt % Ga, and 0.25 wt % K supported on alumina. We observed a synergy between Ga and Pt, resulting in a highly active and stable catalyst. Additionally, we propose a bifunctional active phase, in which coordinately unsaturated Ga³⁺ species are the active species and where Pt functions as a promoter.     

Investigation of opto-dielectric properties of Ti-doped Ga2O3 thin films

Several Ti-incorporated Ga-oxide (Ga₂O₃) thin films with different amounts of Ti contents have been prepared by vacuum evaporation method on glass and silicon substrates. The Ti incorporation level was measured with energy dispersion X-ray spectroscopy (EDX) method. The crystalline structure of the prepared films was determined with X-ray diffraction method. Experimental data indicate that Ti⁴⁺ ions doped in host Ga₂O₃ form solid solutions (SS) even with so large Ti% content ∼10.4% wt. All the prepared solid solutions have the known orthorhombic (ɛ-phase) phase of Ga₂O₃. The doping controls the optical and electrical properties of the host Ga₂O₃. It was found that the bandgap of the prepared undoped Ga oxide is 5.23 eV, which was decreased monotonically with increasing of Ti doping level so that it is possible to engineer the bandgap. Furthermore, the electrical measurements show that with Ti doping, it is possible to turn the high-k Ga oxide into low-k dielectric material. The optical sensitivity of the capacitance, dissipation factor, and ac-conductance of the Ga₂O₃:Ti films grown on Si was studied as a function of Ti-doping level. It was observed that the prepared Ga₂O₃:Ti film with 6–10% doping level has the highest photosensitivity among the other samples.     

DFT Simulations of Water Adsorption and Activation on Low‐Index α‐Ga2O3 Surfaces

Density functional theory (DFT) calculations are used to explore water adsorption and activation on different α‐Ga₂O₃ surfaces, namely (001), (100), (110), and (012). The geometries and binding energies of molecular and dissociative adsorption are studied as a function of coverage. The simulations reveal that dissociative water adsorption on all the studied low‐index surfaces are thermodynamically favorable. Analysis of surface energies suggests that the most preferentially exposed surface is (012). The contribution of surface relaxation to the respective surface energies is significant. Calculations of electron local density of states indicate that the electron‐energy band gaps for the four investigated surfaces appears to be less related to the difference in coordinative unsaturation of the surface atoms, but rather to changes in the ionicity of the surface chemical bonds. The electrochemical computation is used to investigate the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) on α‐Ga₂O₃ surfaces. Our results indicate that the (100) and (110) surfaces, which have low stability, are the most favorable ones for HER and OER, respectively.     

Magnetic control of bioelectrocatalytic processes based on assembled iron oxide particles

A facile magnetic control system was designed in bioelectrocatalytic process based on functionalized iron oxide particles. The iron oxide particles were modified with glucose oxidase, and ferrocene dicarboxylic acid was used as electron transfer mediator. Functionalized iron oxide particles can assemble along the direction of applied magnetic field, and the directional dependence of the assembled iron oxide particles can be utilized for device purposes. We report here how such functionalized magnetic particles are used to modulate the bioelectrocatalytic signal by changing the orientation of the applied magnetic field.     

Immobilization of In2O3 nanoparticles on the surface of reduced graphene oxide

This communication describes a new method for immobilizing indium oxide nanoparticles (∼20 nm) on the surface of reduced graphene oxide. Dispersion of graphene oxide with added In₂O₃ nanoparticles was treated in supercritical isopropanol, both a reducing agent of graphene oxide and a reaction medium. The resulting nanocomposite was characterized by different methods of physical and chemical analysis.     

一种新颖层状磷酸镓化合物[Ga3(PO4)4](H3NCH2CH2)2NH2的合成与结构表征

晶体结构;水热合成;一种新颖层状磷酸镓化合物[Ga3(PO4)4](H3NCH2CH2)2NH2的合成与结构表征     

Cr2O3-Rh/Ga2O3光催化分解水的时间分辨红外光谱研究

研究半导体光催化分解水反应中光生电荷动力学和助催化剂的作用对理解其反应机理至关重要.一般来说,助催化剂不仅可以促进半导体/助催化剂界面处的光生电荷高效分离,而且可以作为反应活性中心来直接催化表面氧化或还原反应.Cr2O3-Rh是一种重要的产氢助催化剂,通过担载Cr2O3-Rh助催化剂来提高光催化分解水的策略被应用到许多...     

ChemInform Abstract: Intermetallic Compounds Ce4Ru3Ga3 and La3Ru2Ga2 with Crystal Structures of New Types.

Ce₄Ru₃Ga₃ (I) and La₃Ru₂Ga₂ (II) are synthesized by arc melting of the elements under Ar followed by annealing (873 K, 30 d).     

Ga2O3-La2O3-Yb2O3-Er2O3(HO2O3)体系光谱性质的研究

根据稀土离子能级的特点,对Ga2O3-La2O3-Yb2O3-Er2O3(HO2O3)体系的光谱性质进行了探讨,发现它们有二类发光性质:Stokes发光和反Stokes发光,研究了发光强度和发射波长与掺杂离子的依赖关系,观察到由能量的共振转移引起的荧光浓度猝灭现象,并取得了最大发光强度时的掺杂离子浓度和一些规律性结果.     

Ga2O3对Pt/WO3/ZrO2催化剂上正庚烷异构化反应的促进作用

考察了Ga2O3掺杂的Pt/WO3/ZrO2(Pt/WGZ)催化剂在200℃时正庚烷临氢异构化反应性能.结果表明,少量Ga2O3的加入能显著提高Pt/WGZ的催化活性,异构化选择性也有所增加,这是由于B酸位增加和B酸/L酸比的改变而引起的.Pt/WGZ催化剂连续反应80 h,正庚烷转化率和异构化选择性分别稳定在76%和94%.