Supplementary Information
Facile Synthesis of MnO2/CNTs Composite for Supercapacitor Electrodes with Long Cycle Stability Li Li,1,2 Zhong A. Hu,*1 Ning An,1 1
Yu Y. Yang,1 Zhi M. Li,1 and Hong Y. Wu1
Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of
Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, Gansu 730070, China. 2
College of Chemical Engineering, Northwest University for Nationalities, Lanzhou,
Gansu 730030, China.
XPS analysis
0
200
400
600
800
Mn 2p3/2
Intensity (a.u.)
O 1s Mn 2p3/2
11.6eV
C 1s
Mn 3p Mn 3s
Intensity (a.u.)
a
Mn 2p1/2
1.
1000
635
Binding energy (eV)
4.96eV
Mn 2p1/2
640 645 650 655 Binding energy (eV)
660
Mn 3s
Intensity (a.u.)
c
b
80
85 90 Binding energy (eV)
95
Figure S1 (a) XPS, (b) Mn 2p XPS and (c) Mn 3s XPS spectra of MnO2/CNTs composite. Figure S1a shows a typical overall XPS spectrum of the composite, which suggested that the composite is composed of Mn, O and C elements. In the Mn 2p region (Figure S1b), the Mn 2p3/2 peak is centered at 643.01 eV and the Mn 2p1/2 peak at 654.61 eV, with an energy separation of 11.6 eV, which matches with the reported data for MnO2.1,2 2.
Raman analysis
ID:IG=0.45
2D D
500 1000 1500 2000 2500 -1 Raman shift (cm )
571 648
b
G Intensity (a.u.)
Intensity (a.u.)
a
D ID:IG=1.21 G 2D D'
500 1000 1500 2000 2500 -1 Raman shift (cm )
Figure S2 Raman spectrum of (a) the pristine CNTs and (b) MnO2/CNTs composite. Figure S2b shows a typical spectrum of the MnO2/CNTs composite over the measured spectral range. Four characteristic peaks of CNTs at 1329 (D band), 1580 (G band), 1615 (D′ band) and 2663 cm-1 (2D band) are clearly observed from this figure, as reported previously.3-6 Among them, the D band is attributed to the defects in the curved graphene sheet on the nanotubes and the G band represents the crystalline structure of the nanotubes. Usually, the intensity ratio of D to G band (ID/IG) is an important yardstick to measure the degree of defects of carbon materials.7 Compared with the ID/IG value of the pristine CNTs (Figure S2a), the ID/IG value of the composite increased greatly. Near the G band, the D′ vibrational mode, which does not exist in pure graphite, is observed with high intensity in intercalated graphite compounds.8-10 In addition, two sharp, low frequency bands at about 571 and 648 cm-1 for the composite are in good agreement with the birnessite-type MnO2 compounds previously reported.11, 12 3.
TG analysis
Figure S3 TG curves of MnO2/CNTs composite. 4.
Wettability test
Figure S4 Contact angle measurement of (a) the pristine CNTs and (b) MnO2/CNTs composite. 5.
BET test
100
pristine CNTs 2 -1 surface area: 51m g Adsorption Desorption
60 40 20 0
120
3
Quantity Adsorbed (cm /g)
0.0
200 160
MnO2/CNTs composite 2 -1
80
surface area: 71m g
60
Adsorption Desorption
40 20 0 0.0
0.2 0.4 0.6 0.8 1.0 Relative Pressure (p/p0)
2 -1
surface area: 317m g
120 Adsorption Desorption
80 40 0.0
c
100
b pure MnO2
0.2 0.4 0.6 0.8 1.0 Relative Pressure (p/p0)
3
80
3
a
Quantity Adsorbed (cm /g)
120
dV/dlog(D) (cm /g)
3
Quantity Adsorbed (cm /g)
140
0.2 0.4 0.6 0.8 1.0 Relative Pressure (p/p0)
0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00
d MnO2/CNTs MnO2 CNTs
0
10
20
30
40
Pore Diameter (nm)
Figure S5 Nitrogen adsorption-desorption isotherms of (a) the pristine CNTs, (b) the pure MnO2, and (c) the MnO2/CNTs composite. (d) BJH pore size distributions plot.
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