irradiation. All samples were irradiated with a focused light of
150 W XBO lamp through the 10 cm water filter and 420 nm cutoff
filter for 90 s with a total irradiance of 551 W m2
. Contact angles
were measured using Surftens Universal instrument (OEG).
Water droplets were placed in at least three different positions
for each plate and the average value of measured contact angles
was calculated.
Transmission Electron Microscopy images were recorded using
JEM100 SX, 80 kV (JEOL) facility. The scanning electron microscopy
(SEM) images were recorded with a JEOL JSM-7500F Field Emission
apparatus operated at 15 kV. The samples were analyzed without
any surface pretreatment.
The thickness of TiO2 films was measured by a spectroscopic
ellipsometry (J.A. Woollam Co., M-2000). The data analysis was
done using the Cauchy dispersion model.
2.4. Photoelectrochemical measurements
Photocurrent measurements were performed using a typical
three-electrode setup. The experiments were conducted in the
aqueous 0.1 mol dm3 KNO3 (pH 7) electrolyte. The electrolyte
was purged with argon or oxygen for at least 30 min prior to the
measurement. A platinum wire was used as the counter electrode,
while Ag/AgCl electrode was used as the reference one. A 150 W
XBO lamp (Osram), equipped with a water cooled housing, LPS
200 power supply (Photon Technology International), an automatically
controlled monochromator and a shutter, was used as a light
source. The working electrodes (ITO-coated transparent foil with
casted and dried material) were irradiated from the backside
(through the ITO layer), in order to minimize the influence of the
film thickness on the photocurrent magnitude. The measurements
were performed with an electrochemical analyzer BAS-50 W (Bioanalytical
Systems). Measured photocurrents and incident light
intensities were used to calculate incident photon to current effi-
ciencies (IPCE).