As described in the title, I want to know the mechanism of the hydroxylation of the surface of silica by using piranha solution. By the way, is the hydroxylation process similar with the ozone cleaning process of silica surface?
Many thanks to anyone help me!
The degree of hydroxylation depends on many factors like the type (bridged or terminal) and density of hydroxyl groups—I think, this is what hydroxylation degree you are concerned. And It is surface hydroxyl groups which make surface hydrophilic. Piranha solution, due to its strong oxidation power, removes organic contaminants (hydrocarbons) on the surface of Si (it is always covered with a natural SiO2 layer of course at ambient conditions). UV/Ozone and O2 plasma are also good for removing hydrocarbons. But you need to be careful to link directy the surface cleanness with the degree of surface hydroxylation, you may need more surface chemistry techniques to make a strong claim.
Anyway, you may be interested in having a look at our recent paper on critical cleaning of sapphire. D. Zhang, Y. Wang, Y. Gan*, Characterization of Critically Cleaned Sapphire Single-Crystal Substrates by Atomic Force Microscopy, XPS and Contact Angle Measurements, Applied Surface Science, 274 (2013) 405-417. Here is the official link to it and you may also find the full-text on my RG home page. http://dx.doi.org/10.1016/j.apsusc.2012.12.143
https://www.researchgate.net/post/Hydroxylating_a_silicon111_silicon_oxide_surface,kindly check this link.
https://www.x-mol.com/paper/1364715547579215872,this link may be useful.
Dear Dr Wei Huang . See the useful RG link: Article Hydroxylation methods for mesoporous silica and their impact...
Please check this paper: Euro. Poly. J. 2017, 96, 414-428. The Caro's acid generate hydroxyl radicals that could break Si-H or Si-O bond and form Si-OH.