Nano Res.
Electronic Supplementary Material
Simultaneous optical and electrochemical recording ofsingle nanoparticle electrochemistry
Linlin Sun, Yimin Fang, Zhimin Li, Wei Wang (), and Hongyuan Chen ()
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University,Nanjing 210093, China
Supporting information to DOI 10.1007/s12274-017-1439-0
S1 Characterizations of nanoparticles
The nanoparticles used in the present work were characterized by transmission electron microscopy (TEM)
to access the morphology and size distribution. TEM analysis gives an average diameter of 61 ± 25 nm for
Ag nanoparticles (Fig. S1(a)) and 195 ± 30 nm for SiO2 nanoparticles (Fig. S1(b)). The UV–vis spectrum of Ag
nanoparticles shows the spherical colloids have an absorption peak at ca. 413 nm (Fig. S1(c)).
Figure S1 TEM image and size distribution (inset) of Ag nanoparticles (a) and SiO2 nanoparticles (b). (c) UV–vis absorption spectrum of Ag nanoparticles
Address correspondence to Wei Wang, [email protected]; Hongyuan Chen, [email protected]
| www.editorialmanager.com/nare/default.asp
Nano Res.
S2 Schematic illustration of an Au microelectrode
Figure S2 (left) Schematic illustration of an Au microelectrode. (right) Bright-field image of the microelectrode (60× objective).
S3 Distribution of collision locations
We collected collision locations of 40 Ag nanoparticles. Figure S3 shows that the distribution of collision locations
in the gold film surface is uniform.
Figure S3 Distribution of collision locations of Ag nanoparticles in the gold film surface at the potential of 300 mV in 0.1 M KNO3.
S4 Effect of the low-pass filter bandwidth of the Axon
We performed the potential step to a 10 μm Au ultramicroelectrode (UME) in 0.1 M KNO3 from 0 to 300 mV under
different electronic filters (Fig. S4). It was found that a low-pass filter significantly broaden the electrochemical
current spike.
Figure S4 (a) Transient current spike from the potential step under different electronic filters (2, 4, 10, and 20 Hz). (b) Relationship between the width of the electrochemical current spike and the low-pass filter bandwidth of the Axon.
www.theNanoResearch.com∣www.Springer.com/journal/12274 | Nano Research
Nano Res.
S5 Conversion from SPR intensity to theoretical current of single nanoparticles
The amount of charge transfer is equal to the number of dissolved (oxidized) Ag atoms from the particles, so
we have
3
A Agd( 4 / 3 )d
d d
eN r mQi
t t
(S1)
where i, ρ, mAg, NA and r are the theoretical current, density of silver, mass of silver atom, Avogadro’s constant,
and the radius of the particle, respectively.
In our previous study, SPR intensity is proportional to the nanoparticle volume [S1] and we obtain a quantitative
model
SPRlog 2.52 2.84 logI r (S2)
where ISPR and r are the SPRM intensity and the radius of the particle, respectively.
Combining Eqs. (S1) and (S2), we can calculate theoretical current.
At the same time, we can use Eq. (S1) to calculate the size of AgNP from electrochemical current, which was
generally consistent with the TEM characterization. Figure S5 shows the theoretical average diameter of 30
individual AgNPs was 45 ± 15 nm.
Figure S5 The theoretical size distribution of 30 individual AgNPs.
S6 Descriptions of movies
Movie S1 Collision and oxidation of three Ag nanoparticles (potential: 300 mV, and electrolyte: 0.1 M KNO3).
Reference
[S1] Fang, Y. M.; Wang, W.; Wo, X,; Luo, Y. S.; Yin, S. W.; Wang, Y. X.; Shan, X. N.; Tao, N. J. Plasmonic imaging of electrochemical
oxidation of single nanoparticles. J. Am. Chem. Soc. 2014, 136, 12584–12587.