Supporting Information
Double Oxidation with Oxygen and Hydrogen Peroxide for Hole-Forming in Single Wall Carbon Nanohorns
Jianxun Xu,*1,2 Minfang Zhang,1 Maki Nakamura1, Sumio Iijima,1,2 Masako Yudasaka1*
1 Nanotube Research Center, National Institute of Advanced Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, 305-8565, Japan
2 Meijo University, 1-501 Shiogamaguchi, Tenpaku-ku, Nagoya 468-8502, Japan
Supporting Information I
Raman spectra measured with JASCO NRS2100 spectrometer (excitation wavelength: 514.5 nm) are shown in Fig. SI-1 and peak height ratios of G and D bands (IG/ID), in Table SI-1.
The Raman spectrum of SWCNHox500 had G (~1590 cm-1) and D (~1350 cm-1) broad bands. There was a shoulder (~1600 cm-1) on the G band. The D band and a shoulder band indicated that the SWCNHox500 had the defective structure. These spectra features were similar after immersion in H2O2 solutions, and the intensity ratio of G and D bands were similar. These suggested that the base structure of nanohorns, that is, graphenes, were not severely damaged by the immersion in H2O2 solutions at room temperature.
Figure SI-1 Raman spectra of SWCNHas, SWCNHox500, and SWCNH-H2O2-Xd’s.
Table SI-1. IG/ID of the Raman spectra of SWCNHs samples.
SWCNHas / 0.8
SWCNHox500 / 0.9
SWCNHox-H2O2-1d / 0.9
SWCNHox-H2O2-2d / 0.8
SWCNHox-H2O2-4d / 0.9
SWCNHox-H2O2-6d / 0.9
SWCNHox-H2O2-11d / 0.9
SWCNHox-H2O2-26d / 0.7
Supporing Information II
We designate the samples stained with hexaammine Pt(IV) (Pt(NH3)6(OH)4) as SWCNHasPt, SWCNHox500Pt, or SWCNHox-H2O2-XdPt. The samples were observed with TEM and their TGAs were performed in O2 up to 1000 oC at a ramp rate of 10 oC/min. The Pt-complex particle sizes in the TEM images were measured by using the Gatan Digital Micrograph software.
The representative TEM images of SWCNHasPt, SWCNHox500Pt, SWCNHox-H2O2-6dPt, and SWCNHox-H2O2-26dPt are shown in Fig. SI-2. Many spherical black spots in the TEM images correspond to Pt-complex particles which are most likely decomposed form of Pt complexes upon electron beam irradiation. Histograms of the nano-particle sizes measured in TEM images are shown in Fig. SI-3. The particle sizes were large on SWCNHasPt and SWNCHox500Pt, while those on SWCNH-H2O2-XdPt were smaller though they slightly increased from the 6-day immersion to 11- or 26-day immersion.
The results of SWCNHasPt, SWCNHox500Pt, and SWCNHox-H2O2-26dPt corresponded to the results of Yuge et al.: The Pt-complex particle sizes were large on nanohorns with few carboxyl groups, while they were small on nanohorns with plenty of carboxyl groups, indicating that the position of small Pt-complex particles corresponded to the sites of carboxyl groups.
We also measured the quantity of Pt by TGA in O2. The TGA curves of SWCNHasPt, SWCNHox500Pt, and SWCNHox-H2O2-XdPt measured in O2 up to 1000 oC are shown in Fig. SI-4a. We supposed that the residue of each sample after TGA was Pt oxide. The residual quantity was plotted with the H2O2 treatment time, presented in Fig. SI-4b. It can be seen that the residual quantity, corresponding to the quantity of the hybrid Pt complexes, increases with the H2O2 treatment time, especially at the early stage. This is in good agreement with our TGA results (Fig. 5c) that the number of carboxyl groups increased till 6d, reaching almost saturation at 11d and 26d.
Figure SI-2. TEM images of SWCNHasPt (a), SWCNHox500Pt (b), SWCNHox-H2O2-6dPt (c), and SWCNHox-H2O2-26dPt (d). The scale bar is 20 nm in the TEM images, and 5 nm in the insets.
Figure SI-3. The Pt-complex particle size histograms for SWCNHasPt, SWCNHox500Pt, SWCNHox-H2O2-XdPt (X: 1, 2, 4, 6, 11, 26).
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Figure SI-4 (a) Results TGA measured in O2 atmosphere for SWCNHasPt, SWCNHox500Pt, and SWCNHox-H2O2-XdPt. The inset is the zoomed part of the patterned area (600-1000oC). (b) Weight percents of Pt residues after TGA (Fig. SI-5(a)) plotted with the immersion periods in H2O2.
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