Supporting Information Wiley-VCH 2009 69451 Weinheim, Germany High-Index Faceted Platinum Nanocrystals Supported on Carbon Black as Highly Efficient Catalysts for Ethanol Electrooxidation** Zhi-You Zhou, Zhi-Zhong Huang, De-Jun Chen, Qiang Wang, Na Tian, and Shi-Gang Sun* anie_200905413_sm_miscellaneous_information.pdf
1. Identification of atomic steps 1.1 Models of different atomic steps {110} {310} CNs=7 CNs=6 CNs=6 Figure S1. Models of {110}, and {310} atomic steps along <100> crystal zone axis. {311} {211} CNs=7 CNs=7 Figure S2. Models of {311} and {211} atomic steps along <110> crystal zone axis.
{311} CNs=7 CNs=6 Figure S3. Models of {311} and atomic steps along <211> crystal zone axis. 1.2 Assignment of atomic steps of HIF-Pt nanoparticle along <100> crystal zone axis. {310} {200} {310} {110} {310} {510 } {310} {510} 2 nm Figure S4. Comparison between models of atomic steps and aberration-corrected HRTEM images of one HIF-Pt nanocrystal along <100> crystal zone axis. The good agreement between models and real atomic images confirms that the HIF-Pt nanoparticles contain high density of atomic steps (CNs<8).
2. In situ FTIR spectroscopic studies of ethanol oxidation In situ FTIR spectroscopic studies were carried out on a Nicolet 870 FTIR spectrometer equipped with a liquid-nitrogen-cooled MCT-A detector and an EverGlo IR source. A thin-layer IR cell with a CaF 2 planar window was employed. Infrared radiation sequentially passed through the CaF 2 window and the thin-layer solution, and then was reflected from the electrode surface. The resulting spectra were reported as relative change in reflectivity, that is, R R( ES ) R( ER ) = (1) R R( ER ) where R(E S ) and R(E R ) are the single-beam spectra collected at sample potential (E S ) and reference potential (E R ), respectively. As a result, for solution species, downward bands in the resulting spectra indicate the formation of products, while upward bands denote the consumption of reactants. The spectral resolution was 8 cm -1. 2.1 Assignment of species in the FTIR spectra Table S1 Assignment of IR bands in the spectra for ethanol oxidation in Figure 1 Wavenumbers / cm -1 Assignments [s1] Comments 1044 The other upward band of ethanol at 1086 cm -1 was ν C O CH (upward) 3 CH 2 OH swamped by intensive absorption of ClO - 4 at 1100 cm -1. 2343 ν as Ο=C=O CO 2 The final oxidation product generated from the cleavage of C-C in ethanol. ~ 1720 ν C=O CH 3 COOH This band is usually distorted due to the changing of spectral background (e.g., interference from the H 2 O absorption at 1640 cm -1 ). 1392 δas CΗ 3 CH 3 CHO / 1370 δs CΗ 3 1280 ν C O CH 3 COOH 1100 ν ClO 4 ClO 4 - ~ 2050 ν CO Adsorbed CO (CO ad ) / This band is characteristic for acetic acid, and is usually used for quantitative analysis of acetic acid. The increase of ClO - 4 (diffusion from bulk solution to the thin-layer solution) is caused by the product of H + from ethanol oxidation (e.g., CH 3 CH 2 OH + 3H 2 O 2CO 2 + 12H + + 12e). At 0.60 V (SCE), CO ad can be oxidized quickly. So this band was originated from reference spectrum (i.e., at 0.25 V), and may be generated from the dissociative adsorption of ethanol. In the time-resolved FTIR spectra collected at 0.60 V (Figure S5), we can observe that this band is nearly independent on time. The band direction is reversed due to CO adsorbed on nanomaterials that exhibit abnormal infrared effects (AIREs). [s2]
2.2 In situ time-resolved FTIR spectra HIF-Pt/C Commercial Pt/C 5 s 15 s 25 s 5 s 15 s 25 s R/R=2.0 10-2 t R/R=2.0 10-2 t 155 s 155 s 165 s CO ad CO 165 s HAc ad ClO 4 CO CO 2 HAc 2 ClO 4 2400 2000 1600 1200 ν 2400 2000 1600 1200 / cm -1 ν / cm -1 Figure S5. In situ time-resolved FTIR spectra of ethanol oxidation on HIF-Pt/C and commercial Pt/C at 0.60 V. Time resolution: 10 s; E R = 0.25 V; 0.1 M ethanol + 0.1 M HClO 4 solution. Figure S5 shows the in situ time-resolved FTIR spectra of ethanol oxidation on HIF-Pt/C and commercial Pt/C at 0.60 V (SCE). The band at ~2050 cm -1 is attributed to linear-bonded CO, and its intensity is nearly independent on time. At the potential as high as 0.60 V, adsorbed CO (CO ad ) can be oxidized quickly, so this CO band was originated from the reference spectrum collected at 0.25 V. The time dependence of IR band intensities of solution species, i.e., CO 2 and acetic acid, illustrated clearly that more CO 2 and less acetic acid are produced on the HIF-Pt/C as compared with the commercial Pt/C.
Reference [S1] D. Lin-Vien, N. B. Colthup, W. G. Fateley, J. G. Grasselli, The Handbook of Infrared and Raman Characteristics Frequencies of Organic Molecules, Academic Press, New York, 1991. [S2] G.Q. Lu, S.G. Sun, L.R. Cai, S.P. Chen, Z.W. Tian, K.K. Shiu, Langmuir 2000 16, 778.