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Supplementary information
Photocatalytic Activity of Nitrogen doped TiO2-based Nanowires: A Photo-Assisted 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:
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 assignmentN 1s / 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
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 % / 398.7 eV, 0.07 at %
400.2 eV, 0.18 at %
401.8 eV, 0.06 at %
407.4 eV, 0.13 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 % / -NH2 and other contaminants
Ti 2p3/2 / 458.8 eV, 22.33 at % / 458.8 eV, 24.22 at % / 458.8 eV, 23.83 at % / 458.9 eV, 24.45 at % / TiO2
O 1s / 530.0 eV, 43.48 at % / 530.0 eV, 48.75 at % / 530.0 eV, 46.95 at % / 530.1 eV, 50.17 at % / TiO2
530.9 eV, 4.91 at % / 531.3 eV, 5.31 at % / 531.2 eV, 5.75 at % / 531.4 eV, 3.87 at % / TiOH
532.0 eV, 3.63 at % / 531.4 eV, 1.65 at % / 532.5 eV, 1.94 at % / 532.2 eV, 1.99 at % / C-O
C 1s / 285.3 eV, 12.66 at % / 285.2 eV, 6.37 at % / 285.3 eV, 8.04 at % / 285.2 eV, 6.27 at % / C-(C,H)
286.9 eV, 1.6 at % / 286.8 eV, 0.95 at % / 287.0 eV, 1.01 at % / 286.7 eV, 0.96 at % / C-OH
288.7eV, 2.01 at % / 288.9 eV, 2.16 at % / 288.9 eV, 2.34 at % / 289.0 eV, 1.71 at % / COOH
289.6 eV, 0.59 at %
Pd3d5/2 / - / 334.7 eV, 0.28 at % / - / 334.7 eV, 0.23 at % / Pd (0)
- / 335.5 eV, 0.13 at % / - / 335.4 eV, 0.07 at %
- / 336.5 eV, 0.23 at % / - / 336.4 eV, 0.3 at % / PdO
- / 338.0 eV, 0.05 at % / - / 338.1 eV, 0.04 at % / Pd(II)
Pt4f7/2 / 70.9 eV, 0.26 at % / 71.0 eV, 0.37 at % / Pt(0)
72.1 eV, 0.11 at % / 72.3 eV, 0.1 at % / 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 / TiO2-NP-Pd / TiO2-NP-NPd / TiO2-NP-PdN / Peak assignmentsN 1s / Not detected / 396.7 eV,
0.1 at % / Not detected / Not detected / 395.8 eV
0.1 at % / TiN
396.5 eV
0.1 at %
400. 3 eV;
0.8 at % / 399.6 eV
0.1 at %
400.9 eV,
0.4 at % / 400.2 eV,
0.8 at % / 400.3 eV,
0.6 at % / 397.9 eV
0.2 at %
400.2 eV
1.4 at % / -NH2 and other contaminants
Ti 2p3/2 / 458.8 eV;
27.9 at % / 458.8 eV;
27.0 at % / 458.8 eV;
24.7 at % / 458.8 eV;
25.4 at % / 458.8 eV;
25.4 at % / TiO2
O 1s / 530.0 eV;
53.2 at % / 530.0 eV;
53.9 at % / 530.0 eV;
49.1 at % / 530.0 eV;
51.8 at % / 530.0 eV;
48.3 at % / TiO2
531.0 eV;
6.9 at % / 531.1 eV;
5.3 at % / 531.4 eV;
6.3 at % / 531.4 eV;
5.4 at % / 530.8 eV;
5.4 at % / TiOH
532.3 eV;
5.8 at % / 532.3 eV;
4.7 at % / 532.4 eV;
2.5 at % / 532.5 eV;
2.6 at % / 531.9 eV;
5.4 at % / C-O
C 1s / 284.8 eV
3.1 at % / 285.2 eV,
5.1 at % / 285.2 eV,
9.5 at % / 285.0 eV,
8.6 at % / 285.1 eV,
8.3 at % / C-(C,H)
286.4 eV
1.4 at % / 286.7 eV,
2.4 at % / 286.6 eV,
3.1 at % / 286.6 eV,
2.8 at % / 286.6 eV,
2.5 at % / C-OH
288.9 eV
1.0 at % / 289.1 eV,
1.0 at % / 288.8 eV,
3.8 at % / 288.8 eV,
2.5 at % / 288.9 eV,
2.7 at % / COOH
Pd3d5/2 / - / - / 334.6 eV,
0.1 at % / 334.6 eV,
0.1 at % / 334.5 eV,
0.1 at % / Pd (0)
- / - / 335.5 eV,
0.1 at % / 335.4 eV,
0.03 at % / 335.2 eV,
0.1 at % / PdO
- / - / 336.6 eV,
0.02 at % / 336.4 eV,
0.2 at % / 336.5 eV,
0.04 at % / Pd(II)
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