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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 : 1,751  

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 78
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32 [13.09] -Poly(norepinephrine): Ultrasmooth Material-Independent Surface Chemistry and Nanodepot for Nitric Oxide 09-04 1389
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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 1752
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