Supplemental Material
Examination of interfacial charge transfer in photocatalysis
using patterned CuO thin film deposited on TiO2
K. Osako,1,b) K. Matsuzaki,2,b) H. Hosono,2,3 G. Yin,1 D. Atarashi,1 E. Sakai,1
T. Susaki,2,a) and M. Miyauchi 1,4,a)
1
Department of Metallurgy and Ceramics Science, Graduate School of Science and Engineering, Tokyo Institute of
Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, Japan
2
Secure Materials Center, Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta,
Midori-ku, Yokohama, Japan
3
Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Japan
4 PRESTO,
Japan Science and Technology Agency (JST), 4-1-8, Honcho, Kawaguchi-shi, Saitama, Japan
FIG. S1. X-ray reflection (XRR) pattern
FIG. S2. XRD patterns
FIG. S3. UV-Vis spectra
FIG. S4. AFM images before Ag photodeposition
FIG. S5. XPS spectra of Ag-3d core level on patterned CuO film
FIG. S6. AFM image after photodeposition of Ag particles on pattered CuO film (100 nm thick)
FIG. S7. AFM images after photodeposition of Ag particles on patterned CuO films
log [Intensity (arb. units)]
measured
calculated
2
4
6
8
10
2 (deg)
Rutile 220
CuO 111
Rutile 110
log [Intensity (arb. units)]
FIG. S1. Typical fitting procedure of the X-ray reflection (XRR) pattern for CuO/TiO2. Using this approach, the film
was determined to have a thickness of 5.6 nm.
CuO 30 nm
CuO 9 nm
CuO 6 nm
CuO 3 nm
substrate
20
30
40
50
60
70
80
2 (deg)
FIG. S2. XRS patterns for CuO/TiO2 thin films with various CuO thicknesses. The Cu-K line was used for
measurement.
Absorbance A
0.8
100)
0.28
A(CuO/TiO2) - A(TiO2) (
1.0
6
CuO thickness
100 nm
30 nm
9 nm
6 nm
3 nm
0 nm
(a)
0.6
0.4
(b)
4
2
0
400
500
600
700
800
900
Wave length (nm)
FIG. S3. UV-Vis spectra for CuO/TiO2 thin films (a), and differential spectra versus rutile TiO2 substrate (b). The
steep optical absorption around 420 nm (panel a) is attributed to the band to band transition in rutile TiO2
corresponding to its bandgap of 3.0 eV. The differential spectra (panel b) show absorption just below the energy level
of rutile TiO2 absorption edge. Notably, because the wavelength of the blue light-emitting diode (LED) used in the
present photo-reduction experiment ranged from 425 to 530 nm, this LED cannot excite electrons in the bare rutile
TiO2 but can excite electrons both in CuO thick films and in thin CuO films on TiO2 substrate.
(a)
(b)
D
height
250nm
A
B
C
CuO: 100 nm
TiO2
TiO2
5 m  5 m 0
2 m
CuO: 6 nm
5 m  5 m 0
2 m
(c)
height
30 nm
(d)
A
D
B
C
Intensity (arb. units)
FIG. S4. AFM images before Ag photodeposition for patterned CuO films with thicknesses of (a) 100 nm and (b) 6
nm. AFM line profiles of CuO films with thickness of (c) 100 nm and (d) 6 nm, respectively.
(b)
(a)
376
372
368
364
Binding Energy (eV)
FIG. S5. XPS spectra of Ag-3d core level for 6 nm-thick patterned CuO film, (a) before and (b) after photodeposition.
height
63 nm
63.39
[nm]
0.00
5 m5.00
 5x 5.00
mµm 0
2 m
2.00 µm
FIG. S6. AFM image after photodeposition of Ag particles on the patterned CuO film with 100-nm thickness. The
probed region was very far from the film edges.
(a)
height
250.00
250
[nm] nm
Ag
CuO: 100 nm
µm
55.00
m
(b)
TiO2
10.00 x 10.00 µm
10 m  10 m
00.00
Ag
CuO: 6 nm
TiO2
5.00 µm
10.00 x 10.00 µm
10 m
 10 m
5 m
height
100.00
100nm
[nm]
00.00
FIG. S7. Low magnification AFM images after photodeposition of Ag particles on patterned CuO films with
thicknesses of (a) 100 nm and (b) 6 nm. The edges of the CuO film were formed using photo-lithography (round
shape) and a metal mask (square shape) for the 100-nm and 6-nm thick films, respectively.