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Title: On the origin and underappreciated effects of ion doping in silica
Authors: Song, Xiaohui
Ding, Tao
Yao, Lin
Lin, Ming
Lee, Rachel Siew Tan
Liu, Cuicui
Sokol, Katarzyna
Yu, Le
Lou, David Xiong Wen
Chen, Hongyu
Keywords: DRNTU::Engineering::Chemical engineering::Chemical processes
Issue Date: 2015
Source: Song, X., Ding, T., Yao, L., Lin, M., Lee, R. S. T., Liu, C., et al. (2015). On the origin and underappreciated effects of ion doping in silica. Small, 11(34), 4351-4365.
Series/Report no.: Small
Abstract: The origin of selectivity in the hollowing of silica nanoparticles is investigated to further understand silica. It is realized that, during the synthesis, the silica precursors are essentially ion-paired polyelectrolytes, whose nucleation depends on the concentration of the counter ions, and most importantly, the size/length of the poly(silicic acid). Thus, the “silica” that nucleates out at the different stages of synthesis has different degrees of ion doping, which explains its solubility in water, its microporosity, and the selective etching phenomena. The etching of silica in water is shown to be a matter of silica solubility, which correlates to the relative amounts of solvent and to the solvent quality (the water/isopropanol ratio). Hollowing does not occur when the silica nanoparticles are incubated in solutions presaturated with “silica,” ruling out surface reposition and Ostwald ripening as the hollowing mechanism. The embedded ions in silica are confirmed by elemental analysis (CHNS) and inductively coupled plasma-mass spectrometry. The high ionic doping ratios (N/Si = 2.3% for NH3-catalyzed silica; Na/Si = 11.2% for NaOH-catalyzed silica) explain the unusual solubility of silica in neutral water. The new view of silica with the ionic impurities on the central stage allows for insights in silica properties and versatility in synthetic design.
ISSN: 1613-6810
DOI: 10.1002/smll.201500539
Rights: © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Fulltext Permission: none
Fulltext Availability: No Fulltext
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