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ۼ : 13-02-06 11:36
[13.01]μ -Reversible and Cyclical Transformations between Solid and Hollow Nanostructures in Confined Reactions of Manganese Oxide and Silica within Nanosized Spheres
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ȸ : 1,555  

Reversible and Cyclical Transformations between Solid and Hollow Nanostructures in Confined Reactions of Manganese Oxide and Silica within Nanosized Spheres
-Tae-Lin Ha , Jin Goo Kim , Soo Min Kim , and In Su Lee *

Annealing of MnO@SiO2 nanospheres in a reducing gas environment resulted in the transformation of the core–shell structure into a hollow structure as a result of outward diffusion of MnO species into the thermodynamically more stable silicate phase. When the hollow silicate nanospheres were oxidized, the interior cavities were refilled with a Mn3O4 phase segregated from the silicate phase, and the hollow structure reverted to the initial core–shell structure. More interestingly, when catalytically active Pt nanocrystals were introduced into the manganese oxide/silica system, the Mn3O4 was readily reduced to the chemically reactive MnO, even at low temperature, which enabled reconversion of the solid nanospheres with a Mn3O4 core to hollow nanostructures during reductive annealing. Therefore, when MnO@SiO2/Pt(II) nanospheres were subjected to an oxidation/reduction cycle by repeatedly switching the flowing gas between air and hydrogen, the nanospheres underwent a reversible change between solid and hollow structures, depending on the gas environment. The solid-to-hollow-to-solid transformation was successfully cycled many times simply by repeatedly switching the flowing gas during annealing.


 
 

Total 73
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27 [13.4]⹮ -Free-Standing, Single-Monomer-Thick Two-Dimensional Polymers through Covalent Self-Assembly in Solution 11-25 1150
26 [13.3]⹮ -Supramolecular Velcro for Reversible Underwater Adhesion 11-25 1082
25 [13.01] -Active Role of Proton in Excited State Intramolecular Proton Transfer Reaction 06-19 1374
24 [13.01]μ -Reversible and Cyclical Transformations between Solid and Hollow Nanostructures in Confined Reactions of Manganese Oxide and Silica within Nanosized Spheres 02-06 1556
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21 [12.06]μ - Electroless Pt Deposition on Mn3O4 Nanoparticles via the Galvanic Replacement Process 07-03 1929
20 [12.06]Ž± -Surface-Dependent, Ligand-Mediated Photochemical Etching of CdSe Nanoplatelets 06-14 1619
19 [12.05]⹮ -In Situ Supramolecular Assembly and ModularModification of Hyaluronic Acid Hydrogels for 3D Cellular Engineering 11-25 854
18 [12.01] -Coherent Electronic and Phononic Oscillations in Single-Walled 03-05 1846
17 [12.02]ؿ -Ferritin-Based New Magnetic Force Microscopic Probe Detecting 10 nm Sized Magnetic Nanoparticles 02-17 1765
16 [11.11]踸, -Ionic Surfactant–Coated Burkholderia Cepacia Lipase as a Highly Active and Enantioselective Catalyst for the Dynamic Kinetic Resolution of Secondary Alcohols 12-27 2254
15 [11.2] -DNA-Functionalized Nanochannels for SNP Detection 02-22 3569
14 [11.1]⹮ -Supramolecular fishing for plasma membrane proteins using an ultrastable synthetic host–guest binding pair 11-25 1026
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