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S-1
Supporting Information
Spatially Resolved Electrochemistry Enabled by Thin-Film Optical
Interference
Yafeng Wang, Qian Yang and Bin Su*
Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University, Hangzhou 310058, China
As shown in Figure S1, no obvious redox current was observed for SNM/ITO with CTAB surfactants in silica
nanochannels (blue curve), indicating that the SNM was integrated and uniform over large area (centimeter scale).
Meanwhile, obvious redox current, similar to that of ITO/glass (Figure S1, red curve), was seen (Figure S1, black
curve) after removal of CTAB surfactants from nanochannels. These results are similar to those reported
previously.1,2
Figure S1. CVs of ITO/glass (red curve), SNM/ITO with CTAB surfactants in nanochannels (blue curve) and
SNM/ITO (black curve) in 50 mM KHP solution (pH = 4) containing 0.5 mM Ru(NH3)63+. The potential scan
rate was 50 mV/s.
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S2. Interferometric Electrochemistry Responses of SNM/ITO in KCl Solution
The concentration of KCl near the electrode surface will change with the sweep of applied potential. To exclude
the effect of concentration of KCl on the value of ΔI, the experiments depicted in Figure 3b were also performed
in 0.1 M and 1 M KCl solution, respectively (Figure S2a and b). The value of ΔI changed slightly with the
concentration of KCl, revealing that the variation of concentration of KCl contributed slightly to the value of ΔI.
Figure S2. Interferometric electrochemistry responses of SNM/ITO in 0.1 M KCl solution (a) and 1 M KCl solution
(b). The potential scan rate was 20 mV/s.
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S3. Interferometric Responses of ITO/glass During Electrochemical Process
Figure S3. Changes of ΔI with the sweep of potential applied to the ITO/glass in 0.5 M KCl solution (a) and 0.5 M
KCl solution (b) containing 10 mM Ru(NH3)63+. The potential was swept from +0.2 V to 0.45 V. The potential scan
rate was 20 mV/s.
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S4. Relationship between ΔI and Potential Applied on SNM/ITO
Figure S4. The variation of ΔI of SNM/ITO with the potential sweep in 0.5 M KCl solution containing 10
mM Ru(NH3)63+. The potential scan rate was 20 mV/s.
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S5. UV-Vis Spectra of Ru(NH3)63+, Ru(NH3)6
2+, Fe(CN)63 and Fe(CN)6
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Figure S5. UV-Vis spectra of Ru(NH3)63+ (a) and Ru(NH3)6
2+ (b) with different concentrations. (c) UV-Vis spectra of
10 mM Fe(CN)63 and Fe(CN)6
4.
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S6. CVs of SNM/ITO and ITO/glass in Ru(NH3)63+ Solution
Figure S6. CVs of SNM/ITO (a) and ITO/glass (b) in 0.5 M KCl solution containing different concentrations of
Ru(NH3)63+. Black curve: 0 mM, red curve: 0.5 mM, blue curve: 1 mM, green curve: 2 mM, purple curve: 3 mM,
yellow curve: 5 mM, brown curve: 10 mM, red dotted curve: 20 mM, black dotted curve: 30 mM. The potential
scan rate was 20 mV/s.
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S7. CVs of SNM/ITO and ITO/glass in Fe(CN)63 Soution
Figure S7. CVs of SNM/ITO (blue curve) and ITO/glass (red curve) in 0.5 M KCl solution containing 10 mM Fe(CN)63.
The potential scan rate was 20 mV/s.
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S8. Interferometric Electrochemistry Responses of SNM/ITO and ITO/glass in
Fe(CN)63 Solution
Figure S8. The variation of ΔI with the potential sweep for the ITO/glass (a) and SNM/ITO (b) in 0.5 M KCl
solution containing 10 mM Fe(CN)63. The potential scan rate was 20 mV/s.
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S9. Interferometric Electrochemistry Responses of SNM/ITO in Ru(bpy)32+ Solution
Figure S9. The variation of ΔI with the potential sweep for the SNM/ITO in 0.5 M KCl solution containing 10 mM
Ru(bpy)32+. The potential scan rate was 20 mV/s. Note that the Intensity of light reflected from SNM/ITO at 800 nm
was recorded during electrochemical reaction to exclude the effect of light absorption and fluorescence of
Ru(bpy)32+ on the intensity of interferometric light.
The intensity of interferometric light at 800 nm changes significantly during the
electrochemical reactions, indicting the versatility of the method for studying different
molecules.
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S10. Variations of Gray Values of Different Locations on SNM/ITO
Figure S10. (a) Interferometric image of ITO/glass partially coated by SNM. (b) Changes of mean gray values of the
entire SNM/ITO region during CV. (cf) Changes of mean gray values of different locations (marked in (a), 2 × 2
pixels, ca. 800 nm × 800 nm) on SNM/ITO electrode during CV in 0.5 M KCl solution containing 10 mM Ru(NH3)63+.
The potential scan rate was 20 mV/s.
The variations of gray value of the entire SNM/ITO (Fig. S10a and b) during CV were compared with that of different locations (2 × 2 pixels, ca. 800 nm × 800 nm, Fig. S10cf) on SNM/ITO. The tendencies of the curves were different, indicating the heterogeneity of the electrode. Moreover, the mean gray value of different locations began to increase at different times, implying that the EC reactions at different locations began to occur under different potentials. The slope of the curves was also different, revealing the difference of reaction rates at different locations.
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S11. Experimental Section
Chemicals and Materials. Hexaammineruthenium(II) chloride ([Ru(NH3)6]Cl2, 99.9%) was obtained from