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Supplemental Information

Unusual Changes in Electronic Band Edge Energies of Nanostructured

Transparent n-Type Semiconductor Zr-Doped Anatase TiO2 (Ti1-xZrxO2; x <

0.3)

Daniel G. Mieritz, Adèle Renaud and Dong-Kyun Seo

School of Molecular Sciences, Arizona State University,

Tempe, 85287-1604

Table S1. Nominal precursor weights (in grams) used for the synthesis of nanoporous TiO2 and

selected ZTO samples.

Precursor TiO2 10% ZTO 20% ZTO

30% ZTO

Ti(O-Bu)4 6.93 6.24 5.55 4.85

Ethanol 14.47 14.36 13.51 13.14

HNO3 2.49 2.49 2.49 2.49

ZrCl4 0 0.48 0.96 1.44

H2O 3.20 3.20 3.20 3.20

R 2.00 2.00 2.00 2.00

PEG 2.98 2.98 2.98 2.98

ECH 9.52 10.51 12.62 14.00

F 3.04 3.04 3.04 3.04

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Table S2. CHN elemental analysis on selected ZTO products.

Sample Wt% C Wt% H Wt% N

0-500 0.117 0.372 0.015

10-500 0.034 0.233 0.004

20-600 0.064 0.245 0.014

30-500 0.1 0.29 0.015

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Table S3. Electronegativity (χ) and optical energy gap (Eg, eV) values used in the scissor

relationship to predict the conduction band energies (ECB), and the measured flat band energies

(Ufb), combined with the point of zero zeta potential (PZZP) and pH during the measurement

(pHMeas), used to obtain the corrected flat band energy (Ufb0).

Compound χ[a]

Eg

ECB

Ufb

PZZP pHMeas Ufb0 Ref.

TiO2, anatase 5.812 3.19 -4.22 −4.26 5.45 5.05 −4.24 this study

Zr0.1Ti0.9O2 5.816 3.24 -4.20 −4.10 5.45 5.05 −4.08 this study

Zr0.2Ti0.8O2 5.820 3.29 -4.18 −4.03 5.58 5.05 −4.00 this study

TiO2, anatase 5.812 3.32 -4.15 −4.30 5.80 0.00 −3.96 1

TiO2, anatase 5.812 3.40 -4.11 −4.42 5.45[b]

3.00 −4.28 2

TiO2, anatase 5.812 3.40 -4.11 −4.27 5.45[b]

6.00 −4.30 2

TiO2, anatase 5.812 3.40 -4.11 −4.07 5.45[b]

11.00 −4.40 2

TiO2, anatase 5.812 3.20 -4.21 −3.82 5.80 7.00 −3.89 3

TiO2, anatase 5.812 3.20 -4.21 −3.77 5.80 13.70 −4.24 4

TiO2, anatase 5.812 3.20 -4.21 −4.45 5.80 1.00 −4.17 5

TiO2, anatase 5.812 3.20[b]

-4.21 −4.42 5.45[b]

7.00 −4.51 6

Zr0.05Ti0.95O2 5.814 3.23[c]

-4.20 −4.31 5.45[b]

7.00 −4.40 6

ZrO2 5.854 5.00 -3.35 −2.71 6.70 13.30 −3.10 7

ZrO2 5.854 5.00 -3.35 −2.75 6.70 13.30 −3.14 8

Bi2O3 5.917 2.80 -4.52 −5.20 6.20 0.00 −4.83 9

CdO 5.823 2.20 -4.72 −4.55 11.60 13.30 −4.65 8

CuO 5.812 1.70 -4.96 −5.05 9.50 7.00 −4.90 8

Fe2O3 5.867 2.20 -4.77 −4.65 8.60 9.00 −4.67 8

Nb2O5 6.211 3.40 -4.51 −3.72 6.06 13.30 −4.14 10

PbO 5.416 2.80 -4.02 −4.96 8.29 0.00 −4.47 9

SnO2 6.217 3.50 -4.47 −4.82 4.30 0.00 −4.57 9

Ta2O5 6.262 4.00 -4.26 −3.31 2.90 13.30 −3.93 7

TiO2, rutile 5.812 3.00 -4.31 −3.75 5.80 13.00 −4.18 8

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TiO2, rutile 5.812 3.05 -4.29 −4.50 5.80 0.00 −4.16 1

TiO2, rutile 5.812 3.00 -4.31 −3.88 5.80 7.00 −3.95 3

V2O5 6.121 2.80 -4.72 −5.55 6.54 7.00 −5.58 8

WO3 6.567 2.70 -5.22 −4.55 0.43 13.30 −5.31 7

ZnO 5.951 3.20 -4.35 −4.91 8.80 0.00 −4.39 9

BaTiO3 5.244 3.30 -3.59 −3.95 9.00 13.60 −4.22 8

CdFe2O4 5.854 2.30 -4.70 −4.55 7.22 13.30 −4.91 8

FeTiO3 5.689 2.80 -4.29 −3.66 6.30 13.30 −4.07 7

Hg2Nb2O7 6.233 1.80 -5.33 −4.82 6.25 13.30 −5.24 10

KTaO3 5.275 3.50 -3.52 −3.52 8.55 13.30 −3.80 10

PbFe12O19 5.837 2.30 -4.69 −5.75 7.17 13.30 −6.11 11

SrTiO3 5.317 3.40 -3.62 −3.35 8.60 13.00 −3.61 11

[a] All values calculated by the geometric mean of Mulliken electronegativity. Ionization and electron affinity

energies taken from ref. 12. [b]

Measured in this study [c]

Extrapolated from values measured in this study

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Figure S1. Model of the electrochemical circuit employed for impedance measurements on

nanoporous ZTO materials.

RS

RCT

Q

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Figure S2. Elemental analysis results from optical emission spectra compared to the nominal

elemental compositions for the nanoporous ZTO materials. Results from two individually

prepared ZTO sample sets are shown in red and green.

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Figure S3. Powder XRD patterns of nanoporous ZTO samples after calcination at different

temperatures. The patterns shown are (a) TiO2, (b) 10% ZTO, (c) 20% ZTO, and (d) 30% ZTO.

The silicon standard is marked by a vertical black line at 2θ = 28.44°, and the anatase Brag peaks

are indicated by the red vertical lines. Rutile peaks are labeled with ‘R’, and srilankite peaks are

labeled with ‘S’.

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Figure S4. N2 sorption isotherms (a) and BJH pore size distributions (b) for the dense samples

TiO2 (red), 10% ZTO (green), 20% ZTO (blue) and 30 % ZTO (purple).

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Figure S5. Selected area electron diffraction (SAED) patterns of a) 0-500, b) 10-500, c) 20-600

and d) 30-500. The scale bars in (a) – (c) are 2 nm-1

, and in (d) is 5 nm-1

.

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Figure S6. STEM image of 30-500 with corresponding EDS spectra of the different particle

types.

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Figure S7. TEM micrographs ((a), scale bars = 20 nm, 5 nm inset) and SAED pattern ((b), scale

bar 2 nm-1

) of ZTO 20-500.

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Figure S8. Tauc plots, with curves drawn from transmission data of films of 0-500 (red), 10-500

(green), 20-600 (blue) and 30-500 (purple), with linear regions indicated by solid lines whose x-

intercepts estimate (a) the indirect band gaps and (b) the direct band gaps.

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Figure S9. (a) Mott-Schottky plot, obtained at pH 7.48, from films of nanoporous ZTO material

on FTO with increasing Zr doping, and (b) the estimated flat band potentials.

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