Supporting InformationSupporting Information: Electrochromic properties of TiO. 2. nanotubes coated with electrodeposited MoO. 3 David Di Yao,* a. Matthew R. Field, b. Anthony P. O’Mullane,

Supporting Information:

Electrochromic properties of TiO2 nanotubes coated with electrodeposited MoO3

David Di Yao,*a Matthew R. Field, b Anthony P. O’Mullane, b Kourosh Kalantar-zadeh*a and Jian Zhen Ou*a

a School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC

Australia.

b School of Applied Sciences, RMIT University, Melbourne, VIC Australia.

Figure S1. High-angle annular dark field (HAADF) scanning transmission electron

microscopy (STEM) was carried out in addition to SEM to ascertain uniform MoO3 coating

of the TNTs. The dark field formed by the high angle scattered electrons is highly sensitive to

the variations in atomic number of the elements making up the sample. The lighter element

shows up as darker contrast and heavier element as brighter contrast. Titanium (Ti) and

molybdenum (Mo) have atomic numbers 22 and 42, respectively. Ti is represented by the

dark circles in the dark field, which signifies the TNTs, while the brighter Mo is seen to grow

parallel to the interior of the TNTs and around the TNT film.

Electronic Supplementary Material (ESI) for NanoscaleThis journal is © The Royal Society of Chemistry 2013

Figure S2. Twenty random pore diameters on each of ten separate SEM images for every

sample parameter was measured and compiled in a maximum-mean-minimum layout. The

average pore diameter for bare TNT, 2 cycles, 4 cycles 8 cycles and 10 cycles were 70.18,

59.69, 49.84, 40.08 and 40.93 nm respectively.

Table S1. Measurements for pore diameters for the samples are carried out and an average

for each sample was calculated.

TNT 2 cycles 4 cycles 8 cycles 10 cycles

Average 70.1808 59.69285 49.8431 40.08415 40.9347

Minimum 56.71 52.71 39.47 29.81 27.53

Maximum 79.14 70.98 59.81 52.2 49.93

Electronic Supplementary Material (ESI) for NanoscaleThis journal is © The Royal Society of Chemistry 2013

Table S2. X-ray photoelectron spectroscopy (XPS) depth profile of MoO3 coated TNT films

showing the atomic percentage of MoO3 at the surface and depth of 490 nm for samples

formed using 2, 4, 8 and 10 cycles.

Depth 2c 4c 8c 10c

Surface 3.66054 3.99905 3.74315 3.74479

490nm 1.80486 1.62602 2.60592 2.11614

Figure S3. The pre-coloration transmission of every sample is presented to compare the

initial transparency.

Electronic Supplementary Material (ESI) for NanoscaleThis journal is © The Royal Society of Chemistry 2013

Figure S4. In situ transmittance of bare TNT, 4 cycled MoO3 coated TNT and only 4 cycled

MoO3, directly deposited onto FTO, were carried out and compared. Although the only

MoO3 visibly demonstrates no optical density change (∆OD) and bare TNT ∆OD is ~0.02,

the MoO3 coating shows enhanced ∆OD.

Electronic Supplementary Material (ESI) for NanoscaleThis journal is © The Royal Society of Chemistry 2013

Figure S5. Cyclic voltammograms of the stability test for the 4 cycled coated sample was

carried out. A visible increase in the CV current could be contributed to the volume

expansion effect, where more surface area of the film is exposed to the electrolyte as the in

situ measurement carried on.1 This effect has been commonly observed during the EC

reaction2 and is believed to be caused by the strain generated during the ion intercalations.3

References:

1. C. G. Granqvist, Handbook of inorganic electrochromic materials, Access Online via

Elsevier1995.

2. J. Zhang, X. L. Wang, X. H. Xia, C. D. Gu, Z. J. Zhao and J. P. Tu, Electrochim.

Acta, 2010, 55, 6953-6958.

3. J. Scarminio, Sol. Energy Mater. Sol. Cells, 2003, 79, 357-368.

Electronic Supplementary Material (ESI) for NanoscaleThis journal is © The Royal Society of Chemistry 2013