In this work, we investigate the formation of nanobubbles on a surface coated with TiO2 in an aqueous solution by in situ tapping-mode atomic force microscopy (TMAFM). The TiO2-coated surface can generate hydrogen through photocatalytic reaction in methanol/water solution when ultraviolet (UV) light (wavelength λ < 400 nm) is illuminated on the surface. We found that nanobubbles could be produced and existed at the TiO2/water interface during the TiO2 photocatalytic process. By employing a combination of techniques, including phase imaging and contact-mode imaging, we could confirm the gas origin of such observed nanobubbles. In addition, the evolution process of nanobubbles at the TiO2/water interface has also been monitored with time of the photocatalytic reaction.
Journal of Physical Chemistry C,
Vol. 112, no. 11 (Mar 2008), pp. 4029-4032