electronic supplementary information for journal of ... file3 2. sem images of rgo/cu composite...

Electronic Supplementary Information for Journal of Materials

Chemistry A

This journal is © The Royal Society of Chemistry 2013.(Manuscript ID TA-ART-10-2013-014137)

Controllable growth of graphene/Cu composite and its

nanoarchitecture-dependent electrocatalytic activity to hydrazine oxidation

Chengbin Liu,*a Hang Zhang,

a Yanhong Tang,

b and Shenglian Luo*

a

a State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha

410082, P. R. China. E-mail: [email protected]; [email protected]

b College of Materials Science and Engineering, Hunan University, Changsha 410082, P. R. China

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry AThis journal is © The Royal Society of Chemistry 2014

2

1. Raman and X-photoelectron spectra

Fig. S1 (a) Raman spectra of GO and RGO. (b) High-resolution XPS C1s peak of GO and RGO. The

Raman spectra of GO and RGO show characteristic D and G bands, where the D/G intensity ratio

increases in RGO (1.349) relative to GO (0.998). Such increasing is often considered as a sign of GO

reduction occurring, which is mainly because the number of smaller graphitic domains increase after

reduction of GO. XPS confirms the reduction of GO based on the decreasing oxygen content in

RGO, as evidenced by the dominant C=C/C–C peak at 284.5 eV for the RGO sample.

1000 1200 1400 1600 1800 2000

GO

RGOG

Inte

ns

ity

/a

.u.

Raman Shift /cm-1

D

(a)

282 284 286 288 290

C=O

C-OC=C/C-C

Inte

nsit

y /

a.u

.Binding Energy /eV

(b)C1s

RGO

GO


3

2. SEM images of RGO/Cu composite grown in various deposition cycles

Fig. S2 SEM images for RGO/Cu composite prepared from 1 mM [Cu2+

] and 0.3 g L1

GO using

different cycle numbers for electrodeposition. It is found that the RGO is always the topmost layer

irrespective of the cycle numbers.


4

3. CV electrolysis of GO or Cu-EDTA

Fig. S3 CV electrolysis curves of 0.3 g L1

GO (left) and 1 mM Cu-EDTA (right) in 0.067 M pH8

phosphate buffer solution for 10 cycles. It is found that the reduction peak potentials of GO and Cu2+

are –1.21,2

and –0.3 V (versus saturated calomel electrode (SCE)), respectively.

-1.0 -0.5 0.0 0.5-100

-80

-60

-40

-20

0

20

I / A

E / V (vs SCE)

GO reduction

Electrolysis of GO

-1.0 -0.5 0.0 0.5

-250

-200

-150

-100

-50

0

50

I / A

E / V (vs SCE)

Electrolysis of Cu-EDTA

Cu2+ reduction


5

4. XPS measurements

Fig. S4 XPS for (a) L-RGO/Cu, (b) S-RGO/Cu, and (c) H-RGO/Cu. Similar features are observed

for the three composites. The peaks at 932.8 and 952.1 eV are ascribed to the Cu 2P3/2 and Cu 2P1/2

signals of metallic copper or Cu2O (it is difficult to distinguish metallic copper and Cu2O by XPS

features of Cu 2P due to their very closed binding energies), respectively, and the peaks at 934.4 and

954.3 eV are ascribed to the Cu 2P3/2 and Cu 2P1/2 of CuO, respectively.35

The other peaks located at

higher binding energies (940–945 eV and 954–965 eV) can be attributed to satellite peaks

characteristic of CuO.6

970 960 950 940 930

Cu 2P3/2

962.4 954.3

952.1

943.4

940.8

934.4

932.8

Co

un

t /

a.u

.

Binding energy / eV

(a) Cu 2P1/2

970 960 950 940 930

Cu 2P3/2

962.4 954.3

952.1

943.4

940.8

934.4

932.8

Co

un

t /

a.u

.

Binding energy / eV

(b) Cu 2P1/2

970 960 950 940 930

Cu 2P3/2

962.4 954.3

952.1943.4

940.8

934.4

932.8

Co

un

t /a

.u.

Binding energy /eV

Cu 2P1/2(c)


6

5. Cyclic voltammograms of bare GCE and RGO/GCE in K3[Fe(CN)6]

Fig. S5 Cyclic voltammograms at (a) the bare GCE and (b) the RGO/GCE in 0.1 M KCl containing

5 mM K3[Fe(CN)6] at different scan rates (v) of 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 mV s1

. Insets

are the plots of anodic ip versus 1/2

.

-0.4 -0.2 0.0 0.2 0.4 0.6

-60

-30

0

30

60

90

120

0.1 0.2 0.3

20

40

60

v1/2

/ (V s-1)1/2

R = 0.9998

iP = 0.675 + 216.95 v1/2

i P /

A

100 mV s-1

E / V (vs SCE)

I /

A

10 mV s-1

(a)

-0.4 -0.2 0.0 0.2 0.4 0.6

-100

0

100

200

0.1 0.2 0.30

50

100

150

i P /

A

v1/2

/ (V s-1)1/2

I /

A

E / V (vs SCE)

100 mV s-1

10 mV s-1

iP = -20.221 + 502.354 v1/2

R = 0.9982

(b)


7

6. Cyclic voltammograms for the electrodes in the back-ground electrolyte KOH

Fig. S6 Cyclic voltammograms for (a) bare GCE, (b) RGO/GCE, (c) Cu/GCE, (d) L-RGO/Cu/GCE,

(e) S-RGO/Cu/GCE, and (f) H-RGO/Cu/GCE in 0.1 M KOH without N2H4 at the scan rate of 0.1 V

s1

in the potential range of 0.4+0.7 V, with the corresponding integral area (IdV) presented.

-0.4 -0.2 0.0 0.2 0.4 0.6-15

-10

-5

0

5

10

15

20

I /

A

E / V (vs SCE)

(a) bare GCEIntegral area:

0.66 10-5

-0.4 -0.2 0.0 0.2 0.4 0.6

-20

-10

0

10

20

30

40

50

I /

A

E / V (vs SCE)

(b) RGO/GCE

Integral area:

1.51 10-5

-0.4 -0.2 0.0 0.2 0.4 0.6

-20

0

20

40

60

80

I /

A

E / V (vs SCE)

(c) Cu/GCE

Integral area:

1.35 10-5

-0.4 -0.2 0.0 0.2 0.4 0.6-40

-20

0

20

40

60

80

100

I /

A

E / V (vs SCE)

(d) L-RGO/Cu/GCE

Integral area:

1.64 10-5

-0.4 -0.2 0.0 0.2 0.4 0.6

-100

-50

0

50

100

150

200

250

300

I /

A

E / V (vs SCE)

(e) S-RGO/Cu/GCE

Integral area:

7.66 10-5

-0.4 -0.2 0.0 0.2 0.4 0.6-40

-20

0

20

40

60

80

100

120

Integral area:

2.96 10-5

I /

A

E / V (vs SCE)

(f) H-RGO/Cu/GCE


8

7. The effect of scan rate investigated on the RGO and the Cu electrodes

Fig. S7 Cyclic voltammograms at the GCEs loaded with (a1) RGO and (a2) Cu nanoparticles in 0.1

M KOH containing 10 mM hydrazine at various scan rates of 50, 60, 70, 80, 90, 100, 120, 140, 160,

180, 200, and 250 mV s1

. Insets represent the dependence of the peak current on the square root of

the scan rate. (b1) and (b2) represent the dependence of the peak potential in (a1) and (a2),

respectively, on the natural logarithm of the scan rate.

-0.4 0.0 0.4 0.8 1.2

0.0

0.5

1.0

1.5

2.0

0.2 0.4 0.60.5

1.0

1.5

ip(A) = 33.0278 + 2340 v1/2

v1/2

/ (V s-1)1/2

250 mV s-1

I

/ m

A

E / V (vs SCE)

50 mV s-1

(a1)

R = 0.9998

i p /

mA

-0.4 0.0 0.4 0.8

0.0

0.5

1.0

1.5

2.0

0.2 0.3 0.4 0.50.6

0.8

1.0

1.2

R = 0.9996

ip(A) = 169.214 + 2190 v1/2

v1/2

/ (V s-1)1/2I

/ m

A

E / V (vs SCE)

250 mV s-1

50 mV s-1

(a2)

i p /

mA

-1.5 -1.2 -0.9 -0.6

0.3

0.4

0.5R = 0.9957

Ep = 0.640 +0.274 lg v

lgv / lg(V s-1)

Ep

/ V

(b2)

-1.5 -1.2 -0.9 -0.6 -0.3

0.6

0.7

0.8

0.9

R = 0.9980

Ep = 0.989 +0.310 lg v

lgv / lg(V s-1)

EP

/ V

(b1)


9

8. Stability test of the electrodes using cyclic voltammetry

Fig. S8 Cyclic voltammograms for the L-, S-, and H-RGO/Cu composite electrodes in the potential

range of 0.4−+0.7 V at the scan rate of 100 mV s1

in 0.1 M KOH solution containing 10 mM

N2H4. The 1st, 50th, 100th, 150th, 200th, 250th, 300th, 350th, 400th cycles were demonstrated.

References

1. L. Y. Chen, Y. H. Tang, K. Wang, C. B. Liu and S. L. Luo, Electrochem. Commun., 2011, 13,

133.

2. C. B. Liu, Y. R. Teng, R. H. Liu, S. L. Luo, Y. H. Tang, L. Y. Chen and Q. Cai, Carbon, 2011,

49, 5312.

3. L. Martin, H. Martinez, D. Poinot, B. Pecquenard and F. Le Cras, J. Phys. Chem. C, 2013, 117,

4421.

4. S. Gonzalez, M. Perez, M. Barrera, A. R. G. Elipe and R. M. Souto, J. Phys. Chem. C, 1998,

102, 5483.

5. H. C. Gao, Y. X. Wang, F. Xiao, C. B. Ching and H. W. Duan, J. Phys. Chem. C, 2012, 116,

7719.

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3075.

-0.4 -0.2 0.0 0.2 0.4 0.6

0.0

0.2

0.4

0.6

0.8

1.0

1.2

I /

mA

E / V (vs SCE)

1st

400th

S-RGO/Cu

-0.4 -0.2 0.0 0.2 0.4 0.6

0.0

0.2

0.4

0.6

I /

mA

E / V (vs SCE)

1st

400th

L-RGO/Cu

-0.4 -0.2 0.0 0.2 0.4 0.6

0.0

0.2

0.4

0.6

0.8

I /

mA

E / V (vs SCE)

1st

400th

H-RGO/Cu


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