Cobalt sulfides as efficient catalyst towards oxygen reduction reactions

Developing low-cost and high performance catalysts to replace precious metal based catalysts for oxygen reduction reaction(ORR) is one of the most feasible ways to promote the commercial application of fuel cells.In this work,flower-like CoS and octahedral CoS_2 are synthesized by a facile one-pot hydrothermal method without any adjunction of surfactants or follow-up thermolysis,their catalytic performance towards ORR in alkaline electrolyte are comparatively investigated.The results reveal that CoS_2 outperforms CoS owing to the higher electron density around S-S bond of S_2^2- in the crystal structure,which promotes the adsorption of oxygen on catalyst surface and facilitates the breakage of O-O bond in oxygen,leading to direct 4-electron transfer ORR.When CoS_2 particles are dispersed on the surface of rGO with large surface area,their ORR performance could be further improved.     

Fabrication of palladium nanoparticles as effective catalysts by using supramolecular gels

Two-component supramolecular gels were made through self-assembly of tetrazolyl derivatives and Pd(OAc)₂. The robust gels indicated high storage modulus(>10,000 Pa) and loss modulus, which were studied by rheological measurements. The formed Pd nanoparticles(~9 nm) obtained during the formation of the gel showed effective catalytic hydrogenation of nitrobenzene and could be recovered and reused without loss of activity.     

Ultrasound-assisted synthesis of pyrimidines and their fused derivatives: A review

The pyrimidine scaffold is present in many bioactive drugs; therefore, efficient synthetic routes that provide shorter reaction times, higher yields, and site-selective reactions are constantly being sought. Ultrasound (US) irradiation has emerged as an alternative energy source in the synthesis of these heterocyclic scaffolds, and over the last ten years there has been a significant increase in the number of publications mentioning US in either the construction or derivatization of the pyrimidine core. This review presents a detailed summary (with 140 references) of the effects of US (synergic or not) on the construction and derivatization of the pyrimidine core through classical reactions (e.g., multicomponent, cyclocondensation, cycloaddition, and alkylation reactions). The main points that were taken into consideration are as follows: chemo- and regioselectivity issues, and the results of conventional heating methods compared to US and mechanistic insights that are also presented and discussed for key reactions.     

Calcium chloride doped zinc-cobalt metal-cyanide complex:Unexpected highly activity towards ring-opening polymerization of propylene oxide

<正>Highly active calcium chloride(CaCl_2) doped Zn-Co~Ⅲdouble metal-cyanide(Ca-DMC) catalysts were firstly reported.Ca-DMCs presented a very higher polymer yield(54 kg polymer/g catalyst) at relative low temperature(80-115℃) toward ringopening polymerization(ROP) of propylene oxide(PO) than did DMC catalysts without modification.     

Combinatorial Materials Science and Catalysis

After forever changing the drug discovery process in the pharmaceutical industry, combinatorial chemistry methodologies are increasingly being applied to the discovery and optimization of more efficient catalysts and materials (see picture). With the advent of new combinatorial synthesis and screening technologies, coupled with integrated data management systems, the application of these technologies to materials science and catalyst research holds tremendous potential and brings high expectations to this new and exciting field.     

Direct Observation by Electrospray Ionization Mass Spectrometry of [Cp*RhMo3O8(OMe)5]−, a Key Intermediate in the Formation of the Double-Bookshelf-Type Oxide Cluster [(Cp*Rh)2Mo6O20(OMe)2]2−

The use of methanol as solvent is essential for the formation of the double-bookshelf-type oxide cluster [(Cp*Rh)₂Mo₆O₂₀(OMe)₂]²⁻ from [{Cp*Rh(μ-Cl)Cl}₂] and four equivalents of [Mo₂O₇]²⁻. The reaction proceeds via [Cp*RhMo₃O₈(OMe)₅]⁻. The proposed structure for this key intermediate (shown schematically) is supported by electrospray ionization mass spectrometry and labeling experiments with CD₃OD as solvent. Cp*=η⁵-C₅Me₅.     

Studies of sol–gel TiO2 and Pt/TiO2 catalysts for NO reduction by CO in an oxygen-rich condition

The textural properties, morphological features, surface basicity and oxygen reduction behaviours of titania and Pt supported titania catalysts synthesized via a sol–gel method were studied by means of N₂ physisorption, SEM, TEM, CO₂-TPD and H₂-TPR techniques. Mesostructured TiO₂ shows a very narrow pore size distribution that uniformly centred at about 4 nm. High resolution TEM images confirmed that most of Pt particles on Pt/TiO₂-SG had a size smaller than 2 nm. Both the titania support and Pt loaded catalysts chiefly contained weak basic sites with small amount of strong basic sites. Loading Pt did not significantly alter the surface reduction characters of titania, indicating a weak interaction between Pt metals and titania support. Catalytic evaluation revealed that the selectivity of NO reduction over titania was insensitive to variation of textural property. On the bare titania, low NO conversion but high selectivity to N₂O was obtained. However, the Pt/TiO₂-SG catalysts exhibited high NO conversion and high selectivity to N₂, which is assumed to relate to NO dissociation catalysed by the metallic Pt clusters. In addition, when the reaction temperature was above 200 °C, 3–11% NO₂ was yielded over the Pt/TiO₂-SG catalysts, which was discussed on a basis of reaction competition, metal-support interaction and NO dissociation.     

苯酐催化剂表面纹理的表征及表面纹理模型的探讨

大多数实用催化剂均为复杂体系,对其结构和性能进行表征并加以关联是一个重要的问题~[1].表征催化剂可提供化学组成及结构、催化剂纹理及机械性质、催化活性等信息.催化剂纹理是指其几何结构和表面形貌,包括宏观及微观尺度,如颗粒形状、表面积、孔结构、物     

POLYMERIZATION OF BUTYL METHACRYLATE BY IRON PYRIDINEBISIMINE COMPLEXES

Fe(Ⅱ)pyridinebisimine complexes activated with trialkylaluminium or modified methylaluminoxane(MMAO)ascatalysts were employed for the polymerization of butyl methacrylate(BMA).Polymer yields,catalytic activities andmolecular weights as well as molecular weight distributions of BMA can be controlled over a wide range by varying thereaction parameters such as cocatalyst,Al/Fe molar ratio,monomer/catalyst molar ratio,monomer concentration and reactiontemperature used in the polymerization.The catalytic activity of Fe(Ⅱ)complex was 11.1 kg_(polym)/mol_(Fe)h and the highestyield could reach 99.1% under optimum condition.     

Efficient <Emphasis Type="Italic">Baylis-Hillman</Emphasis> Reaction <Emphasis Type="Italic">via</Emphasis> a 1,4-Diazabicyclo[2.2.2]octane-based Ionic Catalyst

Summary. A novel ionic catalyst, 1-butyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride based on 1,4-diazabicyclo[2.2.2]octane was synthesized and applied in the Baylis-Hillman reaction, which occurred readily at room temperature to afford the corresponding adducts in good yield. The ionic catalyst could be recycled for seven runs without diminution in its catalytic activity.