1

Supporting Information

Nanograined surface shell wall controlled ZnO-ZnS core-shell

nanofibers and their shell wall thickness dependent visible

photocatalytic properties

Kuglaur Shanmugam Ranjith,*a Anitha Senthamizhan,

a Brabu Balusamy,

a and Tamer Uyar*

ab

aUNAM - National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.

bInstitute of Materials Science & Nanotechnology, Bilkent University, Ankara, 06800, Turkey

E-mails: K.S.R: ranjith@unam.bilkent.edu.tr, T.U: uyar@unam.bilkent.edu.tr,

Fig. S1. Representative SEM images of as-electrospun PVA/zinc acetate composite NF.

Electronic Supplementary Material (ESI) for Catalysis Science & Technology.This journal is © The Royal Society of Chemistry 2017

2

Fig. S2 EDAX spectra of (g) 30 min and (h) 180 min sulfidated ZnO-ZnS core-shell NF.

20 30 40 50 60 70 80

Zn

O (

10

0)

Zn

O (

00

2)

Inte

nsity (

a.u

)

2 Theta (deg)

ZnS (0016)b

Fig. S3 SEM image and XRD spectrum of ZnO nanostructures sulfidated for 740 min.

3

300 400 500 600

0.0

0.5

1.0

1.5

2.0

Ab

so

rbtio

n

Wavelength (nm)

ZnO

ZnO-ZnS 30 min

ZnS-ZnS 90 min

ZnO-ZnS 180 min

ZnO-ZnS 360 min

ZnO-ZnS 540 min

a

2.6 2.8 3.0 3.2 3.4 3.6

K-M

plo

t

Band gap (eV)

ZnO

ZnS 30 min

ZnS 90 min

ZnS 180 min

ZnS 360 min

ZnS 540 min

b

Fig. S4 (a) UV-Vis DRS absorption spectra and (b) K-M plot for the shell wall controlled ZnO-ZnS core-shell NF.

282 284 286 288 290 292

Inte

nsity (

cps)

Binding energy (eV)

RAW

C-C

C-O

O-C=O

a C 1s

282 284 286 288 290 292

ZnO-ZnS 540 min

ZnO-ZnS 360 min

C 1s

Inte

nsity

(cps

)

Binding energy (eV)

Raw

C-C

C-O

O-C=O

b

ZnO-ZnS 180 min

Fig. S5 XPS spectra of C 1s of (a) as prepared ZnO NFs, (b) C 1s of 180 min, 360 min, 540 min sulfidated ZnO-ZnS

core-shell NF.

4

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Wavelength (nm)

240 min

0 min

a

Ab

sControl MB under UV irradiation

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Wavelength (nm)

Ab

s

Control MB under visible irradiation

240 min

0 min

b

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

160 mins

Ab

s (

a.u

)

Wavelength (nm)

ZnO nanofiber under UV irradiation

0 mins

c

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

160 min

Ab

s (

a.u

)

Wavelength (nm)

ZnO-ZnS (180 min) core shell nanofiber

under UV irradiation0 min

d

400 500 600 700 800400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2e

240 min

Ab

s

ZnO nanofibers under visible irradiation0 min

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

240 mins

Ab

s

Wavelength (nm)

0 mins

ZnO-ZnS (180 min) nanofibers under visible irradiationf

Fig. S6 Time dependent UV-Visible absorption spectra of MB degradation in the presence of electrospun ZnO and

shell wall controlled ZnO-ZnS (180 min) core-shell NF under UV and Visible irradiation.

5

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

240 min

Wavelength (nm)

0 min

Ab

s

ZnO nanofiber catalyst under dark

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Wavelength (nm)

240 min

0 min

Ab

s

ZnO-ZnS (180 min) core shell nanofibers

under dark

Fig. S7 Time dependent UV-Visible absorption spectra of MB dye in the presence of ZnO and ZnO-ZnS 180 min

under dark condition.

Fig S8 Representative digital photographs and degradation spectrum of Rhodamine B in the presence of ZnO and

ZnO-ZnS NF during the photocatalytic measurements under UV irradiation and visible irradiation at different time

intervals.

6

300 400 500 600

0.0

0.5

1.0

1.5

2.0

140 min

Ab

s

Wavelength (nm)

ZnO NF under Visible irradiation

0 min0 min 140 min

300 400 500 600

0.0

0.5

1.0

1.5

2.0

140 min

Ab

s

Wavelength (nm)

0 min

ZnO-ZnS (180 min) under visible irradiation

0 min 140 min

Fig. S9 Representative digital photographs and degradation spectrum of 4-Nitrophenol in the presence of ZnO and

ZnO-ZnS NF during the photocatalytic measurements under visible irradiation at different time intervals.

200 250 300 350 400

0.0

0.5

1.0

1.5

2.0

2.5

3.0

180 min

Ab

s

Wavelength (nm)

ZnO under visible irradiation

0 min

a

200 250 300 350 400

0.0

0.5

1.0

1.5

2.0

2.5

3.0

180 min

Ab

s

Wavelength (nm)

ZnO-ZnS (180 min) under visible irradiation

0 min

b

Fig. S10 Degradation spectrum of 4-cholorophenol in the presence of ZnO and ZnO-ZnS NF during the

photocatalytic measurements under visible irradiation at different time intervals.

7

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

A

bs

Wavelength (nm)

MB

Catalyst + BQ

Catalyst + TEOA

Catalyst + IPA

Catalyst

ZnO as a catalyst

a

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Abs

Wavelength (nm)

MB

Catalyst + BQ

Catalyst + TEOA

Catalyst + IPA

Catalyst

ZnO-ZnS (180 mins) as catalyst

b

400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Abs

Wavelength (nm)

with out catalyst

Catalyst +BQ

Catalyst +TEOA

Catalyst + IPA

Catalyst

ZnO-ZnS (540 mins) as catalyst

c

Fig. S11 Optical absorption spectra of aqueous MB solution photocatalytically degraded using ZnO and ZnS core

NF under visible light irradiation in the absence and presence of BQ (a quencher of O2°), IPA (a quencher of °OH),

TEOA ((a quencher of h+). The photocatalytic reactions were carried out for 140 min time. The dotted line

represents the initial optical absorption of MB solution before photocatalysis.

8

0.0

0.2

0.4

0.6

0.8

1.0

0 50100150200

0.0

0.2

0.4

0.6

0.8

1.0

0 50100150200

0.0

0.2

0.4

0.6

0.8

1.0

0 50100150200

0.0

0.2

0.4

0.6

0.8

1.0

0 50100150200

0.0

0.2

0.4

0.6

0.8

1.0

0 50100150200

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

C/C

o

4 cycle3 cycle2 cycle 5 cycle1 cycle

Time (min)

a

1 2 3 4 5 6 7 8 9 100

20

40

60

80

100

Degra

dation e

ffic

iency

Repeatable cycles

ZnO

ZnO-ZnS (180 min)b

Fig. S12 Recyclic catalytic properties of (a) hierarchical 3h sulfidated ZnO-ZnS core-shell NF and (b) Reusable

catalytic performance up ten cycles

9

Fig. S13 Representative SEM images of electrospun derived (a) ZnO and (b) ZnO-ZnS (180 mins) core-shell NF

after photocatalytic measurements.

1020 1030 1040

1020 1030 1040

1020 1030 1040

1020 1030 1040 1050

ZnO-ZnS before

a ZnO NF before

ZnO NF after

Inte

nsity (

cp

s)

Binding energy (eV)

ZnO-ZnS after

528 530 532 534 536

ZnO after

ZnO before

ZnO-ZnS before

ZnO -ZnS after

b

Inte

nsity (

cp

s)

Binding energy (eV)

Fig. S14 XPS spectra of Zn 2p (a) and O 1s (b) in pristine ZnO and ZnO-ZnS (180 min) core-shell NF before and

after photocatalytic activity.

10

158 160 162 164 166 168 170 172

ZnO-ZnS (180 min) after irradiation

Inte

nsity (

cp

s)

Binding energy (eV)

ZnO-ZnS (180 min) before irradiation

S- 2 2

p

SO

3 2

p

Fig. S15 XPS spectra of S2p of ZnO-ZnS (180 min) core-shell NF before and after photocatalytic activity.

Table S1. XPS results presenting the position and the relative contribution of the Zn, O and S bonding for the shell

wall controlled ZnO-ZnS based core-shell NF.

S.

No

Samples Band gap

eV

O1s

nm

Atomic % Zn 2p

nm

S 2p /SO4

ratio

1 ZnO 3.2 OL - 530.1

Ov - 531.1

Ocl- 532.3

67

26

7

2p 3/2

– 1021.5

2p ½ -1044.6

---

2 ZnO-ZnS 0.5h 2.91 OL - 530.1

Ov - 531.1

Ocl- 532.3

64

27

9

2p 3/2

– 1021.6

2p ½ -1044.7

49.21

3 ZnO-ZnS 1.5h 2.65 OL - 530.1

Ov - 531.1

Ocl- 532.3

34

47

19

2p 3/2

– 1022.5

2p ½ -1045.6

19.43

4 ZnO-ZnS 3h 2.62 OL - 530.1

Ov - 531.1

Ocl- 532.3

25

49

24

2p 3/2

– 1022.8

2p ½ -1045.8

14.28

5 ZnO-ZnS 6h 2.91 OL - 530.1

Ov - 531.1

Ocl- 532.3

17

51

32

2p 3/2

– 1022.8

2p ½ -1045.8

11.02

6 ZnO-ZnS 9h 2.95 OL - 530.1

Ov - 531.1

Ocl- 532.3

12

32

56

2p 3/2

– 1022.8

2p ½ -1045.7

8.09

11

Table S2. Photo responsive properties of shell wall controlled ZnO-ZnS based core-shell NF.

S.

N

o

Hybrid Nano

fibers

Shell wall

thickness

Band edge

absorbance

Degradation

efficiency under

UV in 140 min

(λ = 365 nm)

Degradation

efficiency under

Visible in 150 min

(λ > 400 nm)

Degradation

Rate (min-1

)

(λ = 365 nm)

Degradation

Rate

(λ > 400 nm)

1 ZnO - 387.7 nm 84.64 % 32.27 % 0.0135 0.0028

2 ZnO-ZnS 0.5h ~ 5 nm 418.4 nm 87.37 % 70.21 % 0.0158 0.0091

3 ZnO-ZnS 1.5h ~ 10 nm 457.6 nm 93.78 % 91.58 % 0.0185 0.0155

4 ZnO-ZnS 3h ~ 20 nm 462.7 nm 91.89 % 96.23 % 0.0207 0.0246

5 ZnO-ZnS 6h ~ 40 nm 448.2 nm 83.55 % 80.42 % 0.0127 0.0105

6 ZnO-ZnS 9h > 60nm 398.2 nm 75.51 % 60.87 % 0.0105 0.0057