Supporting Information

Transcription

1 Supporting Information Ultrathin and Ultralong Single-crystal Pt Nanowire Assemblies with Highly Stable Electrocatalytic Activity Bao Yu Xia, Hao Bin Wu, Ya Yan, Xiong Wen (David) Lou,* and Xin Wang* School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore , Singapore * To whom all correspondence should be addressed. X.W. ( wangxin@ntu.edu.sg) and X.W.L. ( xwlou@ntu.edu.sg, homepage: S1

2 Figure S1. FESEM image (a) and corresponding EDX spectrum (b) of Pt nanowire assemblies. Figure S2. XRD pattern of Pt nanowire assemblies. S2

3 Figure S3. (a) FESEM and (b) TEM images of Pt nanoparticles obtained in the absence of KOH. Figure S4. TEM images of the products obtained with different amounts of KOH added in the reaction solution keeping other conditions unchanged: a) 50 mg, b) 100 mg, c) 200 mg, and d) 700 mg. The corresponding high magnification TEM images are shown in the insets. S3

4 Figure S5. (a) FESEM images of Pt products obtained with different amounts of KOH added: (a) 50 mg; (b) 100 mg; (c) 300 mg, (d) 600 mg, (e) 700 mg, and (f) 900 mg. Figure S6. a) Thermogravimetric analysis (TGA) and b) FT-IR spectrum of as-prepared Pt nanowire assemblies. S4

5 Figure S7. a) Wide scan X-ray photoelectron spectroscopy (XPS) spectrum of Pt nanowire assemblies, and the corresponding spectra of Pt4f (b), N1s (c) and C1s (d). Figure S8. a) Wide scan X-ray photoelectron spectroscopy (XPS) spectrum of Pt/C and the corresponding spectrum of Pt4f (b). S5

6 Figure S9. (a) FESEM image and corresponding EDX spectrum of the Pt product obtained by replacing KOH with NaOH. Figure S10. Optical photo images of the mixture solution with different stirring times. S6

7 Figure S11. (a) FESEM images of Pt products obtained with different EG/DMF volume ratios: (a) 2:8, (b) 3:7, (c) 5:5, and (d) 8:2. Figure S12. (a) FESEM images of Pt products using H2O/DMF solution with different volume ratios: (a) 2:8, (b) 4:6, (c) 6:4, and (d) 8:2. S7

8 Figure S13. (a) FESEM images and corresponding EDX spectra of Pt based Pt-Au and Pt-Pd nanowire assemblies obtained with different atomic ratios: 1:3 (a, b) and 3:1 (c, d). Figure S14. (a) HRTEM images of Pt-Au (a, b) and Pt-Pd (c, d) nanowire assemblies indicate the solid solution structure. S8

9 Figure S15. (a) XRD patterns of Pt-based Pt-Au (a) and Pt-Pd (b) nanowire assemblies obtained with different atomic ratios. Figure S16. N 2 adsorption-desorption isotherm of Pt nanowire assemblies. S9

10 Figure S17. Cyclic voltammograms (CV) of Pt nanowire membrane (a, c) and commercial Pt/C (b, d) electrocatalysts for formic acid oxidation recorded in 0.5 M H 2 SO M HCOOH solution (a, b) and methanol oxidation recorded in 0.5 M H 2 SO M CH 3 OH solution (c, d) at a scan rate of 20 mv s -1. S10

11 Figure S18. Electrochemical CO-stripping curves before and after 3000 cycles for Pt nanowires assemblies (a), commercial PtRu/C (b) and Pt/C (c) catalysts in 0.5 M H 2 SO 4 solution with a scan rate of 20 mv s -1. S11

12 Figure S19. Rotation-speed-dependent (from rpm) current potential curves for Pt nanowires assemblies (a, c) and commercial Pt/C (d, e) catalysts before (a, d) and after 3000 cycles (c, e). (b) Koutecky-Levich plot at 0.7 V for Pt nanowires assemblies from the curves shown in (a). (f) Comparison of ORR polarization curves before and after 3000 cycles at 1600 rpm for Pt nanowires (NW) and commercial Pt/C electrocatalysts. The potential is applied with a scanning rate of 10 mv s -1. S12

13 Figure S20. Ring (Fe 2+ Fe 3+ + e - ) and disk (Fe 3+ + e - Fe 2+ ) currents for the determination of the collection efficiency on rotating ring-disk electrode (RRDE) in 0.1 M NaOH electrolyte supplemented with 10 mm K 3 Fe(CN) 6 at a sweep rate of 20 mv s -1 (the ring potential is at 1.1 V vs. RHE). The collection efficiency, N, is then determined from the ring (I R ) and disk (I D ) currents: N = -I R /I D, and yield a value of 0.25 ± 5%, in fairly good agreement with its theoretical value. 1-4 Reference: (1) Markovic, N. M.; Gasteiger, H. A.; Ross, P. N. J. Phys. Chem. 1995, 99, (2) Antoine, O.; Durand, R. J. Appl. Electrochem. 2000, 30, 839. (3) Paulus, U. A.; Schmidt, T. J.; Gasteiger, H. A.; Behm, R. J. J. Electroanal. Chem. 2001, 495, 134. (4) Markovic, N. M.; Schmidt, T. J.; Stamenkovic, V.; Ross, P. N. Fuel Cells 2001, 1, 105. S13

14 Figure S21. Ring (I R ) and disk (I D ) currents during oxygen reduction (from rpm) on Pt nanowires assemblies (a, b) and commercial Pt/C (c, d) catalysts in 0.5M H 2 SO 4 at a sweep rate of 10 mv s -1 (the ring potential is 1.1 V vs. RHE). S14