Electronic Supplementary Information (ESI) Stepwise synthesis

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is © The Royal Society of Chemistry 2018
Electronic Supplementary Information (ESI) Stepwise synthesis of [email protected] yolk-shell nanocages with much enhanced electrocatalytic performances both in solar cells and hydrogen evolution reactions
Yudi Niu, Xing Qian,* Jie Zhang, Weimin Wu, Hongyu Liu, Chong Xu and Linxi Hou* College of Chemical Engineering, Fuzhou University, Xueyuan Road No. 2, Fuzhou 350116, China. *E-mails: [email protected]; [email protected] Fax: +86-0591-2286 6244; Tel: +86-0591-2286 5220.
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Fig. S1. SEM images of the cracked (a) [email protected], (b) CoS/CoS2-C, (c) [email protected] after ultrasonic treatment, and (d) tungsten light scanning electron microscopy (TLSEM) image of [email protected]
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Counts

1600
S
1200
800
CCo
400 O Si
0

[email protected]

Element Atom percent ()

Co

8.15

S

17.46

C

74.39

Co

Cu

Co Cu

0 2500 5000 7500 Energy (eV)
Fig. S2. EDX spectra image of [email protected]

10000

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ZIF-67
5 10 15 20 25 30 35 40 2 Theta (degree)
Fig. S3. XRD spectra of ZIF-67.
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Intensity (a.u.)

(0 2 2)
(1 1 2)
(0 2 2) (0 1 3)
(2 2 2)
(1 1 4) (2 2 3) (1 3 4)
(0 4 4)

(0 1 1)

Pore volumn (cm3g-1nm-1)

(a) 0.03 0.02 0.01 0.00 1

2.18 nm

[email protected] a-CoS

4.90 nm

10

100

Pore diameter (nm)

(b) 0.03 0.02

CoS/CoS2-C [email protected]

Pore volumn (cm3g-1nm-1)

0.01

0.00

40

80 120 160

Pore diameter (nm)

Fig. S4. Pore-size distribution of [email protected], a-CoS, CoS/CoS2-C and [email protected]

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Table S1. Pore-structure parameters derived from the BET curves.

Samples

Pore volume(cm3 g−1)

Specific area (m2 g−1)

[email protected]

0.322

161

CoS/CoS2-C

0.109

13.9

[email protected]

0.081

12.3

a-CoS

0.153

43.9

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100

90

Weight / %

80

70
60
50
40 0

[email protected] CoS/CoS2-C [email protected]

50.6% 47.2%

200 400 600 800

67.4% 62.9% 57.4% 53.6%
1000 1200

Temp. / ℃

Fig. S5. Thermogravimetric (TGA) curves of [email protected], CoS/CoS2-C and [email protected] samples.

Thermogravimetric analysis (TGA) of these samples was performed in air atmosphere to investigate the compositions of [email protected], CoS/CoS2-C and [email protected] (Figure S5, ESI). A weight loss below 200 °C was measured for the samples, which was ascribed to the disappearance of adsorbed water. The observed weight loss between 200 and 500 °C was mainly attributed to the combustion of the C element.1 An increase in weight, followed by a decrease in weight, which was observed between 500 and 735 °C, was ascribed to an initial oxidation of CoS2/CoS transforming to CoSO4. Then, the subsequent decomposition of CoSO4 transformed to Co3O4 between 735 °C and 890 °C. During this temperature, the mass content of the residual Co3O4 of the samples [email protected], CoS/CoS2-C and [email protected] was 50.6%, 57.4% and 67.4%, respectively. At the end, the stable mass content of CoO which was transformed by Co3O4 from 890 to 910 °C has been recorded as 47.2%, 53.6% and 62.9%, respectively. By calculations, the roughly estimated mass loading of CoS2/CoS in [email protected], CoS/CoS2-C (the main component can be observed as CoS2, according to the XRD result) and [email protected] were 77.4%, 87.9% and 76.3%, respectively.

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Current density (mA/cm2)

20

15

Intitial

10

2000th cycle

5

0

0.0

0.4

0.8

Potential (V)

Fig. S6. J−V curves of [email protected] before and after 2000 times CV cycles.

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Fig. S7. (a) SEM image and (b, c) TEM images of [email protected] after the HER test.
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300

Measured

250

Calculated

200

H2 (umol)

150

100

50

0

0 20 40 60 80 100 120
Time (min)
Fig. S8. Calculated (solid line) and measured (red dot) amount of hydrogen at different times for [email protected] at a constant current density of 20 mA cm−2 in 0.5 M H2SO4.

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