Facet control and Three-dimensional Cu2O Films by
electrodeposition and Its Photoelectrochemical
Properties
Sanghwa Yoon1), Jaehong Lim2), Bongyoung Yoo1)
1)Department
of Materials Engineering, Hanyang University, Korea
2)Electrochemistry Research Group, Materials Processing Division, Korea Institute of
Materials Science, Korea
Hanyang University
2014. 09. 30
 Renewable Hydrogen Energy
Solar-fuel conversion
“Store” photoconverted energy in chemical bonds
Sun
H2
O2
H2
O2
O2
Energy
Water splitting
H2O
Fuel cell
 What is water splitting?
O2
Sun
H2
-
-
+
Photoelectrochemical cell
 Why is design of electrode important at water splitting?
 Surface area
Interface between
electrode and electrolyte
 Surface recombination
 Band bending
LOD
 Optical absorption depth
LC
Carrier diffusion
length
 Bulk recombination
 Minority carrier diffusion length
Nanostructure
 pH (platband potential)
Electrolyte
Electrode
Electrolyte
 Concentration
 Different facets with bath pHs
(a) pH 8.3
Non-Polar (b) pH 12
- SEM images of Cu2O film on Au/Ti coated Si substrate-
Polar
 Different facets with bath pHs
pH 12
Au(111)
Intensity (a.u.)
Cu2O(111)
pH 8.3
Cu2O(100)
pH 12
pH 8.3
30
40
2theta (degree)
- XRD patterns of the planar Cu2O films (pH 8.3, 12) -
50
 Enhanced Photocurrent of Cu2O films by different facets
with bath pHs
Current (mA)
0.0
-0.2
-0.4
-0.6
-0.6
pH 8.3
pH 12
-0.4
-0.2
Voltage (V vs Ag/AgCl)
- LSV curves of the planar Cu2O films (pH 8.3 and 12) -
 0.053mA⇒ 0.28mA: 5.3 times increase (-0.45V vs. Ag/AgCl)
0.0
 Fabrication of Three-dimensional Cu2O film
1)
2)
3)
PS beads
Cu2O layer
Au/Ti coated Si wafer
 Schematic of 3D Cu2O fabrication process
1) Fabrication of Multilayer polystyrene(PS) beads template
2) Electrodeposition of Cu2O
3) Dip Cu2O films in chloroform solution for removing of PS beads template
 SEM images of Three-dimensional Cu2O film
310nm
pH 8.3 (310nm)
pH 12 (310nm)
pH 12 (310nm)
{100}
(111)
{100}
- SEM images of the PS beads template and the disordered 3D Cu2O films (310, 1000nm PS beads) -
 Combination of two surface modification methods at an
angstrom to micro level
☞ (111) Orientation + 3D structure
0.2
0.0
Current (mA)
-0.2
-0.4
-0.6
Planar(pH 8.3)
Planar(pH 12)
3D(pH 12)
-0.8
-1.0
-0.6
-0.4
-0.2
0.0
Voltage (V vs Ag/AgCl)
(1) Large interface area between Cu2O and electrolyte
- LSV curves of the planar and disordered 3D Cu2O films
(pH 8.3 and 12) -
(2) Improve light absorption by light scattering and
trapping
(3) Reduce minority carrier diffusion length (electrons,
50nm~100nm)
0.053mA(pH 8.3) ⇒ 0.28mA(pH 12): 5.3times
⇒ 0.45mA(PS bead template):
1.6times (-0.45V vs. Ag/AgCl)
 Acknowledgement
This research was supported by the Pioneer Research Center Program
through the National Research Foundation of Korea funded by the
Ministry of Science, ICT & Future Planning(NRF-2012-0001262)
This work was supported by the Human Resources Development
program(No.20124030200130) of the Korea Institute of Energy
Technology Evaluation and Planning(KETEP) grant funded by the Korea
government Ministry of Trade, Industry and Energy.
Thank you