Intense and wavelength-tunable photoluminescence from surface functionalized MgO nanocrystal clusters

We report fancy brilliant photoluminescence (PL) from surface functionalized MgO nanocrystal clusters (NCs). Single-crystal-like MgO NCs were prepared by a simple one-pot pyrolysis method in the mixed organic solvent of octylamine (OTA) and oleic acid (OA) using magnesium acetate as a precursor. Under the chemical equilibrium of etching and re-growth with the assistance of OA, the MgO products were surface functionalized. It was found that such surface functionalized MgO NCs exhibited intense visible light PL with high PL thermal-stability, and the apparent quantum yield was as high as 19 +/- 1%. In addition, through controlling the synthetic temperature and the reaction time, the functionalized surfaces of MgO NCs were facilely tuned, resulting in the tuneable wavelength of the PL from blue-violet to yellow. Different low-coordinated oxygen sites, capping OA and carbonate species on the surface of the MgO nanocrystals were thought to be the origin of PL at different wavelengths. Considering the intense PL, high PL stability at ambient conditions, low cost and low toxicity, such MgO NCs might have potential applications in medicine and biology as a new kind of fluorescent label.National Natural Science Foundation of China[20725310, 20721001, 21073145, 20801045]; National Basic Research Program of China[2007CB815303, 2011CBA00508

Solid state precursor strategy for synthesizing hollow TiO(2) boxes with a high percentage of reactive {001} facets exposed

Three-dimensional, hollow, anatase TiO(2) boxes, each was enclosed by six single-crystalline TiO(2) plates exposed with highly reactive {001} facets, were facilely obtained by calcining a cubic TiOF(2) solid precursor at 500-600 degrees C. The formation of such particular nanostructures is attributed to the hard self-template restriction and the adsorption of F(-) ions from the TiOF(2).National Natural Science Foundation of China[20725310, 20801045, 21021061, 21073145]; National Basic Research Program of China[2007CB815303, 2011CBA00508

Facile syntheses and electrocatalytic properties of porous Pd and its alloy nanospheres

Pd-based catalysts are of great interest both for fundamental research and applications. It still remains a challenge to develop reliable and versatile approaches to prepare Pd-based nanostructures with higher performance and better stability. In this article, a facile solution route has been developed to prepare Pd nanospheres, as well as Pd-Pt, Pd-Ag and Pd-Pt-Ag alloy nanospheres. SEM and TEM investigations revealed that the as-prepared nanospheres were three-dimensionally interconnected porous networks with primary nanoparticles as building blocks. The chemical composition of these nanospheres can be easily adjusted by controlling the molar ratio of precursors. Electrochemical measurements indicated that the electrocatalytic activity of these nanospheres towards formic acid oxidation depended on the composition of the nanospheres. By judiciously adjusting the composition of the Pd based alloy nanospheres, the performance of the Pd based catalysts, i.e., the onset potential of the formic acid oxidation, the corresponding peak current density and the ability to tolerate CO, can be optimized.National Natural Science Foundation of China[20725310, 21021061, 21073145]; Key Scientific Project of Fujian Province of China[2009HZ0002-1]; National Basic Research Program of China[2007CB815303, 2009CB939804]; NCET in Fujian Province Universit

Facile syntheses and enhanced electrocatalytic activities of Pt nanocrystals with {hkk} high-index surfaces

通讯作者地址: Jiang, ZY (通讯作者),Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 2. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 电子邮件地址: [email protected]; [email protected] (Pt) is an outstanding catalyst for many important industrial products. Because of its high cost and scarce reserves, it is very important to improve the performance of Pt catalysts. As the metal nanocrystals (NCs) with high-index surfaces usually show very good catalytic activity because of their high density of atomic steps and kinks, the preparation of Pt NCs with high-index facets has become a very important and hot research topic recently. In this article, we report a facile synthesis of high-yield Pt NCs with a series of {hkk} high-index facets including {211} and {411} via a solvothermal method using Pt(II) acetylacetonate as the Pt source, 1-octylamine as the solvent and capping agent, and formaldehyde as an additional surface structure regulator. Multipod Pt NCs with dominant {211} side surfaces were produced without formaldehyde, while concave Pt NCs with dominant {411} surfaces formed under the influence of formaldehyde. By analyzing the products by IR spectroscopy, we found the presence of CO on the surface of concave Pt NCs with {411} surfaces prepared from the solution containing formaldehyde. It was concluded that amine mainly stabilized the monoatomic step edges, resulting in the {211} exposed surface; with addition of formaldehyde, it decomposed into CO, leading to the formation of {411} surfaces by the additional adsorption of the CO on the {100} terraces. In addition, it was found that the as-prepared Pt NCs with high-index {211} and {411} surfaces exhibited much better catalytic activity in the electro-oxidation of ethanol than a commercial Pt/C catalyst or Pt nanocubes with low-index {100} surfaces, and the catalytic activities of Pt crystal facets decreased in the sequence {411}>{211}>{100}.National Basic Research Program of China 2011CBA00508 National Natural Science Foundation of China 21131005 21021061 21073145 21171141 National Fund for Fostering Talents of Basic Science J1030415 Key Scientific Project of Fujian Province of China 2009HZ0002-

Carbonate ions-assisted syntheses of anatase TiO2 nanoparticles exposed with high energy (001) facets

National Basic Research Program of China [2011CBA00508]; National Natural Science Foundation of China [21021061, 21073145, 21131005]; Fundamental Research Funds for the Central Universities [2010121017]Anatase TiO2 nanoparticles exposed with a remarkable amount (60%) of high-energy (001) facets were synthesized via a fluorine-free hydrothermal route, using K-titanate nanowires as a precursor and urea as a surface regulator. The carbonate ions were found to play a key role in the formation of the exposed (001) facets

Synthesis of Pd-Rh Core-Frame Concave Nanocubes and Their Conversion to Rh Cubic Nanoframes by Selective Etching of the Pd Cores

NSF [DMR-1215034]; Georgia Institute of Technology; China Scholarship Council (CSC); World Class University Program from MEST through NRF [R31-10026

Cu2+-Assisted Synthesis of Hexoctahedral Au-Pd Alloy Nanocrystals with High-Index Facets

National Basic Research Program of China [2011CBA00508, 2007CB815303]; National Natural Science Foundation of China [20725310, 21021061, 21073145, 21131005]; Key Scientific Project of Fujian Province of China [2009HZ0002-1]Controlled syntheses of multicomponent metal nanocrystals (NCs) and high-index surfaces have attracted increasing attention due to the specific physical and chemical properties of such NCs. Taking advantage of copper underpotential deposition as a bridge, hexoctahedral Au-Pd alloy NCs with {hkl} facets exposed were successfully synthesized, while phase separation occurred in the absence of Cu2+ ions. The as-prepared hexoctahedral Au-Pd alloy NCs exhibited very excellent performance in terms of both formic acid electro-oxidation and methanol tolerance due to synergism between the high-index facets and the alloy

Cu2+-Assisted Synthesis of Hexoctahedral Au-Pd Alloy Nanocrystals with High-Index Facets

National Basic Research Program of China [2011CBA00508, 2007CB815303]; National Natural Science Foundation of China [20725310, 21021061, 21073145, 21131005]; Key Scientific Project of Fujian Province of China [2009HZ0002-1]Controlled syntheses of multicomponent metal nanocrystals (NCs) and high-index surfaces have attracted increasing attention due to the specific physical and chemical properties of such NCs. Taking advantage of copper underpotential deposition as a bridge, hexoctahedral Au-Pd alloy NCs with {hkl} facets exposed were successfully synthesized, while phase separation occurred in the absence of Cu2+ ions. The as-prepared hexoctahedral Au-Pd alloy NCs exhibited very excellent performance in terms of both formic acid electro-oxidation and methanol tolerance due to synergism between the high-index facets and the alloy

Synthesis of layered protonated titanate hierarchical microspheres with extremely large surface area for selective adsorption of organic dyes

National Basic Research Program of China [2011CBA00508]; National Natural Science Foundation of China [21131005, 21021061, 21073145, 21171142]; Fundamental Research Funds for the Central Universities [2010121017]In this paper, we report a facile synthesis of layered protonated titanate (LPT) hierarchical microspheres through a one step solvothermal reaction in the presence of hexamethylenetetramine (HMTA). Structural characterizations reveal these LPT hierarchical microspheres with a 3D flower-like morphology are built with self-assembled ultrathin nanosheets that are actually composed of several layers or even a monolayer of protonated titanate with an enlarged interlayer spacing. And it is found that these LPT hierarchical microspheres have a certain extent of absorption in the visible region, showing a yellow colour. The changes of such special LPT nanostructures in interlayer spacing and colour should be attributed to the intercalation of NH4+ or other amino-derivatives generated by the decomposition of HMTA. It is exciting that these LPT hierarchical microspheres possess extremely large surface area, reaching the value of 450 m(2) g(-1), and they display specific selectivity towards methylene blue, compared to methyl orange, cresol red and rhodamine B