Dear all
I have used UVO (UV-Ozone) treatment to create -OH end on SiO2 surface. It seems to work pretty well, but I can't find any articles explaining the exact mechanism. In my opinion, H2O vapor in the air might be the one supporting H atoms to form -OH ends. However, hydroxylation occurs anyway after quite a long gas purge with N2+O2 gas. My setup may not purge the air perfectly, but I'm still questioning the source of H atom during -OH end formation. If you know the mechanism of hydroxylation of SiO2 with UVO or have some articles about it, please let me know.
Thanks.
If you are sure the hydrogen doesn't come from outside the silica (the gas phase), the alternative answer is that it comes from inside the silica - in other words, from water and OH groups trapped inside the solid that somehow diffuse to the surface. Complete removal of water from silica requires long annealing to >1000C.
You may be able to test this theory by first generating your silica from a D2O medium rather than H2O. Trapped D2O and OD groups, if they subsequently diffuse to the surface, will be easily distinguishable from H2O and OH by FTIR.
The assumption of H2O vapor active role is quite feasible as far as an UV-assisted ozonolysis of H2O vapor obviously could lead to some hydroxylation - https://spartanwatertreatment.com/advanced-oxidation-uv-ozone/.
Further about the possible mechanism you could refer to:
Article Characterization, modeling and physical mechanisms of differ...
- Article Reactions and Diffusion of Water and Oxygen Molecules in Amo...
Hope these will help.
- Badges
- Science topic
- Similar topics
- Phytochemistry
- Extracts