Manipulating the formation of cesium lead bromide nanocrystals oleic acid.

To realize the precise modulation among the cesium lead halide perovskite-related phases is one of the most fascinating subjects and has motivated increasing research. The formation mechanisms of different phases of cesium lead halide have not been fully recognized. In this work, we reported the phase-selective synthesis of CsPbBr nanorods and CsPbBr nanocrystals (NCs) in amine-free systems, simply by adjusting the dosage of oleic acid (OA).

Evolution of Photoluminescent CdS Magic-Size Clusters Assisted by Adding Small Molecules with Carboxylic Group.

We report our investigation on the formation of photoluminescent CdS magic-size clusters (MSCs), which exhibit absorption peaking at 373 nm, along with sharp band edge emission at ∼385 nm. Denoted as MSC-373, the MSCs were synthesized from the reaction of cadmium oleate (Cd(OA)) and S powder in 1-octadecene at room temperature, together with the addition of acetic acid (HOAc) or acetate salts (M(OAc), M = Zn and Mn) during the prenucleation stage (120 °C). The morphology of as-synthesized MSC-373 was dot-like, which could be altered to flake-like morphology after purification.

Transformation of ZnS Precursor Compounds to Magic-Size Clusters Exhibiting Optical Absorption Peaking at 269 nm.

We report our investigation on the transformation pathway from precursor compounds (PCs) to magic-size clusters (MSCs) for semiconductor ZnS. We show, for the first time, a synthetic approach to ZnS MSCs in a single-ensemble form exhibiting optical absorption peaking at 269 nm. We thus symbolize the MSCs as MSC-269.

Identifying Clusters and/or Small-Size Quantum Dots in Colloidal CdSe Ensembles with Optical Spectroscopy.

It is well-known that optical absorption and photoluminescence (PL) provide information that is sensitive to the size and size distribution of colloidal binary semiconductor quantum dots (QDs). To explore the nature of reaction products, clusters, and/or small-size QDs, we show that it is important to perform as well photoluminescence excitation (PLE) spectroscopy. For two non-hot-injection reactions of cadmium oleate (Cd(OA)) and selenium (Se) in 1-octadecene (ODE), we show that sequentially extracted products displayed a similar apparent red shift in both absorption and PL with a full width at half-maximum (fwhm) of ∼30 nm.

Hydrothermal synthesis of mesoporous silica spheres: effect of the cooling process.

Hydrothermal methods have been widely used in the fabrication of silica-based micro-/nanomaterials. In this paper, we comprehensively investigated dissolution/regrowth kinetics of solid silica in alkaline media under relatively high temperature hydrothermal conditions (typically 180 °C). A decoupled dissolution and regrowth mechanism was proposed to explain the transformation of solid silica to mesoporous silica spheres in the presence of CTAB surfactant.

Ultrathin Ca-PO4-CO3 solid-solution nanowires: a controllable synthesis and full-color emission by rare-earth doping.

It was found that calcium carbonate (CaCO(3)) and hydroxyapatite (Ca(10)(OH)(2)(PO(4))(6)), which are two crucial constituents of the most abundant minerals in nature and very important bioinorganic components in the tissues of mineralizing organisms, can form solid solutions in a wide range of PO(4)(3-)/CO(3)(2-) (P/C) ratios at low temperature when prepared as ultrathin nanowire structures. This is due to the special reactivity of ultrasmall nanocrystals, which can effectively lower the synthetic temperature and promote the formation of solid solutions. The as-prepared ultrathin nanowires with suitable P/C ratios presented strong blue luminescence due to the existence of abundant defects strengthened by CO(3)(2-).

Anion-exchange-driven disassembly of a SiO2/CTAB composite mesophase: the formation of hollow mesoporous silica spheres.

Silica-based surfactant/inorganic composite mesophases have been extremely studied. In this work, we developed a mild method to realize the room-temperature disassembly of a SiO(2)/cetyltrimethylammonium bromide (CTAB) mesophase in a neutral medium. Using KMnO(4) as a typical etching agent, SiO(2)/CTAB mesophase spheres were partially disassembled into normal or rattle-type hollow structures.

Solvothermal synthesis of Pt-Pd alloys with selective shapes and their enhanced electrocatalytic activities.

Pt-Pd bimetallic alloy nanostructures with highly selective morphologies such as cube, bar, flower, concave cube, and dendrite have been achieved through a facile one-pot solvothermal synthesis. The effects of shape-controllers (sodium dodecyl sulfate (SDS), ethylenediamine-tetraacetic acid disodium salt (EDTA-2Na), NaI) and solvents (water/DMF) on the morphologies were systematically investigated. The electrocatalytic activities of these Pt-Pd alloy nanostructures toward formic acid oxidation were tested.

Pd cluster nanowires as highly efficient catalysts for selective hydrogenation reactions.

Palladium is a key catalyst invaluable to many industrial processes and fine-chemical synthesis. Although recent progress has allowed the synthesis of Pd nanoparticles with various shapes by using different techniques, the facile synthesis of Pd nanocrystals and turning them into a highly active, selective, and stable catalyst systems still remain challenging. Herein, we report the highly selective one-pot synthesis of monodisperse Pd cluster nanowires in aqueous solution; these consist of interconnected nanoparticles and may serve as highly active catalysts because of the enrichment of high index facets on the surface, including {443}, {331}, and {221} steps.

Hydrothermal synthesis of hollow silica spheres under acidic conditions.

It is well-known that silica can be etched in alkaline media or in a unique hydrofluoric acid (HF) solution, which is widely used to prepare various kinds of hollow nanostructures (including silica hollow structures) via silica-templating methods. In our experiments, we found that stöber silica spheres could be etched in generic acidic media in a well-controlled way under hydrothermal conditions, forming well-defined hollow/rattle-type silica spheres. Furthermore, some salts such as NaCl and Na(2)SO(4) were found to be favorable for the formation of hollow/rattle-type silica spheres.