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Supplementary information
Photocatalytic Activity of Nitrogen doped TiO2-based Nanowires: A PhotoAssisted Kelvin Probe Force Microscopy Study
Ming-Chung Wu,a*Hseuh-Chung Liao,b Yu-Cheng Cho,b Che-Pu Hsu,b Ting-Han Lin,a Wei-Fang
Sub, András Sápi,c Ákos Kukovecz,c,d Zoltán Kónya,c,e Andrey Shchukarev,f Anjana Sarkar,f
William Larsson,f Jyri-Pekka Mikkola,f,i Melinda Mohl,g Géza Tóth,g Heli Jantunen,g Anna
Valtanen,h Mika Huuhtanen,h Riitta L. Keiski,h and Krisztián Kordásg
a) Department of Chemical and Materials Engineering, College of Engineering, Chang Gung
University, Taoyuan 33302, Taiwan.
b) Department of Materials Science and Engineering, National Taiwan University, Taipei 10617,
Taiwan.
c) Department of Applied and Environmental Chemistry, University of Szeged, H-6720 Szeged,
Rerrich Béla tér 1, Hungary.
d) MTA-SZTE "Lendület" Porous Nanocomposites Research Group, H-6720 Szeged, Rerrich B. tér 1,
Hungary.
e) MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, H-6720 Szeged, Rerrich B. tér 1,
Hungary.
f) Technical Chemistry, Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden.
g) Microelectronics and Materials Physics Laboratories, Department of Electrical Engineering,
University of Oulu, and EMPART Research group of Infotech Oulu, P.O. Box 4500, Oulu FIN-90014,
Finland.
h) Mass and Heat Transfer Process Laboratory, Department of Process and Environmental
Engineering, University of Oulu, P.O. Box 4300, Oulu FIN-90014, Finland.
i) Industrial Chemistry & Reaction Engineering, Process Chemistry Centre, Åbo Akademi
University, FI-20500, Åbo-Turku, Finland
Tel: +886 3 2118800 ext.3545; E-mail: mingchungwu@mail.cgu.edu.tw
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Table S1: Chemical composition of N-doped and metal decorated TiO2 nanowires assessed by
XPS. The N-doped nanowires are obtained from titania nanowires (not nanotubes). The samples
labeled as N-TiO2-A were prepared by a single step annealing of the titanate nanowires in 2%
NH3 (in N2 buffer, flow of 50 mL/min) at 600 °C for 15 h. The samples labeled as N-TiO2-B were
made in two subsequent calcination steps: first, annealed in air at 600 °C for 12 h to form TiO2
anatase nanofibers and then annealed in 2% NH3 (in N2 buffer, flow of 50 mL/min) at 600 °C for
3 h. The as-obtained N-doped TiO2 nanowires were then decorated with nanoparticles of Pd and
Pt of 1wt.% loading by wet impregnation from their acetylacetonates (dissolved in acetone). The
dried and impregnated samples were annealed in air at 300 °C for 2 h, and then reduced in 15%
H2 (in Ar) at 500 °C for 4 h to form the products (Wu et al. 2011).
N-TiO2-A-Pt
N-TiO2-A-Pd
N-TiO2-B-Pt
N-TiO2-B-Pd
Peak
assignment
395.9 eV, 0.05 at %
396.9 eV, 0.03 at %
395.8 eV, 0.04 at %
396.6 eV, 0.04 at %
Not detected
Not detected
TiN
N 1s
398.6 eV, 0.15 at %
400.3 eV, 0.43 at %
407.4 eV, 0.08 at %
399.9 eV, 0.3 at %
407.5 eV, 0.07 at %
Ti 2p3/2
458.8 eV, 22.33 at %
530.0 eV, 43.48 at %
530.9 eV, 4.91 at %
532.0 eV, 3.63 at %
285.3 eV, 12.66 at %
286.9 eV, 1.6 at %
288.7eV, 2.01 at %
289.6 eV, 0.59 at %
70.9 eV, 0.26 at %
72.1 eV, 0.11 at %
458.8 eV, 24.22 at %
530.0 eV, 48.75 at %
531.3 eV, 5.31 at %
531.4 eV, 1.65 at %
285.2 eV, 6.37 at %
286.8 eV, 0.95 at %
398.7 eV, 0.07 at %
400.2 eV, 0.18 at %
401.8 eV, 0.06 at %
407.4 eV, 0.13 at %
458.8 eV, 23.83 at %
530.0 eV, 46.95 at %
531.2 eV, 5.75 at %
532.5 eV, 1.94 at %
285.3 eV, 8.04 at %
287.0 eV, 1.01 at %
398.3 eV, 0.06 at %
399.9 eV, 0.3 at %
400.1 eV, 0.2 at %
407.3 eV, 0.03 at %
458.9 eV, 24.45 at %
530.1 eV, 50.17 at %
531.4 eV, 3.87 at %
532.2 eV, 1.99 at %
285.2 eV, 6.27 at %
286.7 eV, 0.96 at %
288.9 eV, 2.16 at %
288.9 eV, 2.34 at %
289.0 eV, 1.71 at %
334.7 eV, 0.28 at %
335.5 eV, 0.13 at %
336.5 eV, 0.23 at %
338.0 eV, 0.05 at %
71.0 eV, 0.37 at %
72.3 eV, 0.1 at %
334.7 eV, 0.23 at %
335.4 eV, 0.07 at %
336.4 eV, 0.3 at %
338.1 eV, 0.04 at %
O 1s
C 1s
Pd3d5/2
Pt4f7/2
3
-NH2 and
other
contaminants
TiO2
TiO2
TiOH
C-O
C-(C,H)
C-OH
COOH
Pd (0)
PdO
Pd(II)
Pt(0)
PtO
Table S2: Chemical composition of N-doped and Pd decorated TiO2 nanoparticles assessed by
XPS. The N-doped nanoparticles (TiO2-NP-N) are obtained from titania nanoparticles (TiO2-NP)
by a single step annealing in 2% NH3 (in N2 buffer, flow of 50 mL/min) at 600 °C for 3 h. Pd
decorated nanoparticles (TiO2-NP-Pd) were made by wet impregnation from Pd-acetylacetonate
(dissolved in acetone) and subsequent annealing in air at 300 °C for 4 h and reduction in 100%
H2 flow at 500°C for 4h. TiO2-NP-NPd denotes N-doped nanoparticles (TiO2-NP-N) that are
decorated with palladium. TiO2-NP-PdN denotes Pd-decorated TiO2 nanoparticles (TiO2-NP-Pd)
that are subsequently doped with nitrogen in ammonia.
TiO2-NP
TiO2-NP-N
Not detected
396.7 eV,
0.1 at %
N 1s
458.8 eV;
27.9 at %
530.0 eV;
53.2 at %
531.0 eV;
6.9 at %
532.3 eV;
5.8 at %
284.8 eV
3.1 at %
286.4 eV
1.4 at %
288.9 eV
1.0 at %
399.6 eV
0.1 at %
400.9 eV,
0.4 at %
458.8 eV;
27.0 at %
530.0 eV;
53.9 at %
531.1 eV;
5.3 at %
532.3 eV;
4.7 at %
285.2 eV,
5.1 at %
286.7 eV,
2.4 at %
289.1 eV,
1.0 at %
-
-
-
-
-
-
400. 3 eV;
0.8 at %
Ti 2p3/2
O 1s
C 1s
Pd3d5/2
TiO2-NP-Pd
TiO2-NP-NPd
Not detected
Not detected
400.2 eV,
0.8 at %
400.3 eV,
0.6 at %
458.8 eV;
24.7 at %
530.0 eV;
49.1 at %
531.4 eV;
6.3 at %
532.4 eV;
2.5 at %
285.2 eV,
9.5 at %
286.6 eV,
3.1 at %
288.8 eV,
3.8 at %
334.6 eV,
0.1 at %
335.5 eV,
0.1 at %
336.6 eV,
0.02 at %
458.8 eV;
25.4 at %
530.0 eV;
51.8 at %
531.4 eV;
5.4 at %
532.5 eV;
2.6 at %
285.0 eV,
8.6 at %
286.6 eV,
2.8 at %
288.8 eV,
2.5 at %
334.6 eV,
0.1 at %
335.4 eV,
0.03 at %
336.4 eV,
0.2 at %
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TiO2-NP-PdN
395.8 eV
0.1 at %
396.5 eV
0.1 at %
397.9 eV
0.2 at %
400.2 eV
1.4 at %
458.8 eV;
25.4 at %
530.0 eV;
48.3 at %
530.8 eV;
5.4 at %
531.9 eV;
5.4 at %
285.1 eV,
8.3 at %
286.6 eV,
2.5 at %
288.9 eV,
2.7 at %
334.5 eV,
0.1 at %
335.2 eV,
0.1 at %
336.5 eV,
0.04 at %
Peak
assignments
TiN
-NH2 and
other
contaminants
TiO2
TiO2
TiOH
C-O
C-(C,H)
C-OH
COOH
Pd (0)
PdO
Pd(II)