Cationic Gemini Surfactant-Assisted Synthesis of Hollow Au ...
Supporting information
Cationic Gemini Surfactant-Assisted Synthesis of Hollow Au Nanostructures by Stepwise Reductions Wentao Wang, Yuchun Han, Maozhang Tian, Yaxun Fan, Yongqiang Tang, Mingyuan Gao,* and Yilin Wang* Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China Corresponding Author Tel.: +86-10-82615802. Fax: +86-10-82615802. E-mail: [email protected] (Y.L.W.); [email protected] (M.Y.G.).
Preparation of 100 nm Solid Au Nanoparticles for Comparative Study of Methanol Electrocatalytic Oxidation. The 100 nm Au nanoparticles were prepared using a modified seed-mediated growth method. Au seeds were synthesized by the ascorbic acid reduction of HAuCl4 without any surfactant as the capping agent. Briefly, 100 µL of 20 mM HAuCl4 solution was mixed with 10 mL H2O and vortexed, and then 44 µL of 50 mM ascorbic acid solution was injected quickly into the mixture under vigorous mixing. The seed particles were used within 3-5 h after the preparation. The growth solution was prepared as follows: 30 µL of 20 mM HAuCl4 solution and 60 µL of 10 mM C12C6C12Br2 solution were mixed with 2.86 mL H2O and mixed. After that, 29 µL of 50 mM ascorbic acid solution was then added to it and thoroughly mixed. In the mean time, 1.5 mL of the prepared seed solution was added to the growth solution and mixed thoroughly. After the addition of the Au seed solution, the color of the reaction solution changed into light orange, suggesting the formation of larger Au nanoparticles (Figure S1).
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Figure S1. SEM images of the solid Au nanospheres at different magnifications.
Figure S2. TEM and HRTEM images of the as-prepared hollow Au nanospheres (a, b), Au nanocapsules (c, d) and elongated Au nanocapsules (e, f).
2
4.0 0.4 mM C12C6C12Br2 + 0.2 mM HAuCl4
3.5
0.4 mM C12C6C12Br2 + 0.2 mM HAuCl4 + 0.2 mM AA
charge transfer band
Absorbance
3.0 2.5 2.0 1.5
d-d transition band
1.0 0.5 0.0 200
250
300
350
400
450
500
550
600
650
700
Wavelength (nm)
Figure S3. UV-Vis spectra of 0.4 mM C12C6C12Br2 and HAuCl4 before (a) and after (b) the addition of 0.2 mM ascorbic acid.
Figure
S4.
SEM
image
of
the
Au
nanostructures
obtained
from
the
C12C6C12Br2/HAuCl4/Na2SO3 /NaBH4 system.
Figure S5. Photographs (a) and UV-Vis spectra (b) of the reaction of 0.4 mM C12C6C12Br2, 0.2 mM HAuCl4 and 0.2 mM AA solutions at different pH values adjusted by HCl or NaOH.
3
Figure S6. High-resolution TEM image of a single solid nanowire obtained via a one-step reduction by NaBH4.
Figure S7. TEM images of the C12C6C12Br2-Au ions aggregates formed at different AuI/AuIII ratios: 1/4 (a), 1/1 (b) and 4/1 (c). [C12C6C12Br2] = 0.4 mM, [HAuCl4] = 0.2 mM.
Figure S8.
SEM image of the hollow Au nanostructures generated from the
C12C2C12Br2 and HAuCl4 using an identical stepwise reduction approach based on AA and NaBH4. [C12C6C12Br2] = 0.4 mM, [HAuCl4] = [AA] = 0.2 mM, [NaBH4] = 1.2 mM. 4
d
50 40
c
I (µ A)
30 20
b
10
a
0 -10 -20 -30 -40 -50 -60 -70 -0.2
0.0
0.2
0.4
0.6
E / V (Ag/AgCl)
Figure S9. Cyclic voltammograms of Au solid nanosphere (a), hollow nanosphere (b), hollow nanocapsule (c) and hollow elongated nanocapsule (d) in nitrogen-saturated KOH (0.1 M) solution at a scan rate of 50 mVs-1.
5
Cationic Gemini Surfactant-Assisted Synthesis of Hollow Au Nanostructures by Stepwise Reductions Wentao Wang, Yuchun Han, Maozhang Tian, Yaxun Fan, Yongqiang Tang, Mingyuan Gao,* and Yilin Wang* Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China Corresponding Author Tel.: +86-10-82615802. Fax: +86-10-82615802. E-mail: [email protected] (Y.L.W.); [email protected] (M.Y.G.).
Preparation of 100 nm Solid Au Nanoparticles for Comparative Study of Methanol Electrocatalytic Oxidation. The 100 nm Au nanoparticles were prepared using a modified seed-mediated growth method. Au seeds were synthesized by the ascorbic acid reduction of HAuCl4 without any surfactant as the capping agent. Briefly, 100 µL of 20 mM HAuCl4 solution was mixed with 10 mL H2O and vortexed, and then 44 µL of 50 mM ascorbic acid solution was injected quickly into the mixture under vigorous mixing. The seed particles were used within 3-5 h after the preparation. The growth solution was prepared as follows: 30 µL of 20 mM HAuCl4 solution and 60 µL of 10 mM C12C6C12Br2 solution were mixed with 2.86 mL H2O and mixed. After that, 29 µL of 50 mM ascorbic acid solution was then added to it and thoroughly mixed. In the mean time, 1.5 mL of the prepared seed solution was added to the growth solution and mixed thoroughly. After the addition of the Au seed solution, the color of the reaction solution changed into light orange, suggesting the formation of larger Au nanoparticles (Figure S1).
1
Figure S1. SEM images of the solid Au nanospheres at different magnifications.
Figure S2. TEM and HRTEM images of the as-prepared hollow Au nanospheres (a, b), Au nanocapsules (c, d) and elongated Au nanocapsules (e, f).
2
4.0 0.4 mM C12C6C12Br2 + 0.2 mM HAuCl4
3.5
0.4 mM C12C6C12Br2 + 0.2 mM HAuCl4 + 0.2 mM AA
charge transfer band
Absorbance
3.0 2.5 2.0 1.5
d-d transition band
1.0 0.5 0.0 200
250
300
350
400
450
500
550
600
650
700
Wavelength (nm)
Figure S3. UV-Vis spectra of 0.4 mM C12C6C12Br2 and HAuCl4 before (a) and after (b) the addition of 0.2 mM ascorbic acid.
Figure
S4.
SEM
image
of
the
Au
nanostructures
obtained
from
the
C12C6C12Br2/HAuCl4/Na2SO3 /NaBH4 system.
Figure S5. Photographs (a) and UV-Vis spectra (b) of the reaction of 0.4 mM C12C6C12Br2, 0.2 mM HAuCl4 and 0.2 mM AA solutions at different pH values adjusted by HCl or NaOH.
3
Figure S6. High-resolution TEM image of a single solid nanowire obtained via a one-step reduction by NaBH4.
Figure S7. TEM images of the C12C6C12Br2-Au ions aggregates formed at different AuI/AuIII ratios: 1/4 (a), 1/1 (b) and 4/1 (c). [C12C6C12Br2] = 0.4 mM, [HAuCl4] = 0.2 mM.
Figure S8.
SEM image of the hollow Au nanostructures generated from the
C12C2C12Br2 and HAuCl4 using an identical stepwise reduction approach based on AA and NaBH4. [C12C6C12Br2] = 0.4 mM, [HAuCl4] = [AA] = 0.2 mM, [NaBH4] = 1.2 mM. 4
d
50 40
c
I (µ A)
30 20
b
10
a
0 -10 -20 -30 -40 -50 -60 -70 -0.2
0.0
0.2
0.4
0.6
E / V (Ag/AgCl)
Figure S9. Cyclic voltammograms of Au solid nanosphere (a), hollow nanosphere (b), hollow nanocapsule (c) and hollow elongated nanocapsule (d) in nitrogen-saturated KOH (0.1 M) solution at a scan rate of 50 mVs-1.
5
