Electronic Supplementary Material (ESI) for Nanoscale
This journal is © The Royal Society of Chemistry 2012
2
By Jia Lin, a,b
Xiaolin Liu, a
Min Guo, b
Wei Lu, a
Guoge Zhang, b,c
Limin Zhou, d
Xianfeng Chen
*a and Haitao Huang
*b a
Department of Physics, The State Key Laboratory on Fiber Optic Local Area Communication Networks and Advanced Optical Communication Systems, Shanghai Jiao Tong University, Shanghai 200240, China.
E-mail: xfchen@sjtu.edu.cn b
Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University,
Hung Hom, Kowloon, Hong Kong. E-mail: aphhuang@polyu.edu.hk c
School of Materials Science and Engineering, South China University of Technology, Guangzhou, China. d
Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon,
Hong Kong.

Electronic Supplementary Material (ESI) for Nanoscale
This journal is © The Royal Society of Chemistry 2012
Fig. S1.
SEM images of TNAs with a prolonged immersion in water (5 days): (a) top view; (b) cross-sectional view.

Electronic Supplementary Material (ESI) for Nanoscale
This journal is © The Royal Society of Chemistry 2012
Fig. S2.
XRD patterns of water-treated TNAs with a hybrid structure after annealing at
400 °C for 2 h.

Electronic Supplementary Material (ESI) for Nanoscale
This journal is © The Royal Society of Chemistry 2012
Fig. S3.
The equivalent circuit model used to fit the Nyquist curves.
R s
: series resistance. R
CO
/ C
CO
, R
TCO
/ C
TCO
, and R
CE
/ C
CE
are the resistance/capacitance at the FTO/TiO
2
, FTO/electrolyte and Pt electrode/electrolyte interfaces, respectively. W is the impedance of I
−
/I
3
−
diffusion in the electrolyte. R ct
: charge transfer resistance. C  : chemical capacitance. R t
: transport resistance.
The charge transport time was calculated by the relation
 c
= d
2
/2.35
D n
= R t
C  /2.35, where d and D n
are the film thickness and the effective diffusion constant, respectively
[1, 2]
, and

the charge collection efficiency by
 cc
=1−
 c
/
 r
[3]
.
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2. F. Fabregat-Santiago, J. Bisquert, G. Garcia-Belmonte, G. Boschloo and A. Hagfeldt, Sol.
Energy Mater. Sol. Cells , 2005, 87 , 117–131.
3. G. Schlichthörl, N. Park and A. Frank, J. Phys. Chem. B , 1999, 103 , 782–791.