S1

Electronic Supplementary Information for:

Enhanced photochemical activity and stability of ZnS by a simple

alkaline treatment approach

Zain Ul Abideen, Fei Teng*

Jiangsu Engineering and Technology Research Centre of Environmental Cleaning Materials

(ECM), Collaborative Innovation Centre of Atmospheric Environment and Equipment

Technology (CICAEET) , Jiangsu Key Laboratory of Atmospheric Environment Monitoring

and Pollution Control (AEMPC), School of Environmental Science and Engineering,

Nanjing University of Information Science & Technology，219 Ningliu Road, Nanjing

210044, China. Email address: tfwd@163.com (F. Teng)

Electronic Supplementary Material (ESI) for CrystEngComm.This journal is © The Royal Society of Chemistry 2018

S2

Table S1

Physiochemical properties of the as-synthesized samples

Zeta potential Band gap (eV)Samples a Crystallite

size

(nm)

b SBET

(m2g-1) (mV)

Absorption edge

(nm) cKM

method

dDFT

calculation

ZnS 4.52 27.61 -29.6 375 3.26 3.12

1M-ZnS 9.52 60.99 / 370 3.35 /

3M-ZnS 13.18 51.18 +18.0 355 3.50 3.30

5M-ZnS 17.14 37.48 / 358 3.46 /

10M-ZnS 17.13 11.02 / 365 3.43 /

a by Debye Scherer equation for the (111) peaks of ZnS; b calculated by Brunauer-Emmett-Teller (BET) method; c by

Kubelka-Munk function from UV–DRS; d calculated by density functional theory (DFT)

S3

Table S2

FT-IR analysis for ZnS

Peaks Wavenumber (cm-1) Peak intensity Interpretation

1 1397 Small, weak C-H bending

2 1552 Sharp, broad O-H bending (adsorbed water)

3 3331 Broad Associated O-H (adsorbed water)

S4

Table S3

FT-IR analysis for 3M-ZnS

Peaks Wavenumber (cm-1) Peak intensity Interpretation

1 1383 Small, weak C-H bending

2 1625 Sharp, broad O-H bending (adsorbed water)

4 3419 Broad Associated O-H (adsorbed water)

S5

Table S4

Apparent reaction kinetic constants for the degradation of MB under UV light irradiation

(λ ≤ 420 nm)

Samples ZnS 1M-ZnS 3M-ZnS 5M-ZnS 10M-ZnS

k (g mg-1 min-1) 0.0262 0.0312 0.0405 0.0335 0.0234

R2 0.94 0.96 0.93 0.98 0.98

S6

Fig. S1

Fig. S1 FT-IR spectra of the samples; (a) ZnS; (b) 3M-ZnS

4000 3500 3000 2500 2000 1500 1000 500

(a) (b)

Tran

smitt

ance

%

Wavenmber (cm-1)

S7

Fig. S2

Fig. S2 SEM images of the samples; (a) ZnS; (b) 1M-ZnS (c) 3M-ZnS; (d) 5M-ZnS; and (e)

10M-ZnS

(d) (f)

(a) (c)(b)

S8

Fig. S3

Fig. S3 EPR of the samples

0 1000 2000 3000 4000 5000 6000

Inte

nsity

(a. u

.)

Magnetic Field (Gauss)

5M-ZnS

10M-ZnS

S9

Fig. S4

Fig. S4 Zeta potentials of ZnS and 3M-ZnS

-60 -40 -20 0 20 40 60

ZnS 3M-ZnS

+18.0

Total

coun

ts

Zeta potential (mV)

-29.6

S10

Fig. S5

Fig. S5 (a) UV-DRS and (b) Tauc plots of the samples

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

1M-ZnS 5M-ZnS 10M-ZnS

(h)2

Photon Energy (eV)

(b)

200 250 300 350 400 450 500 550 600 650 700

370 nm

1M-ZnS 5M-ZnS 10M-ZnS

Abso

rban

ce (a

.u.)

Wavelength (nm)

(a)

365 nm358 nm

500 nm

S11

Fig. S6

Fig. S6 (a-d) Mott–Schottky plots at fixed frequency of 1 kHz in 0.5 M Na2SO4 (pH = 6.8);

(d) CB and VB potentials

3.0

2.5

2.0

1.5

1.0

0.5

0.0

-0.5

-1.0

-0.377 V

2.973 V

3.35

eV

CB

VB

1M-ZnS

CBCB

VBVB

pH = 6.8

-0.307 V-0.427 V

10M-ZnS5M-ZnS

3.123 V3.033 V

3.43

eV

3.46

eV O2/H2O

Pote

ntial

vs S

HE (V

) H+/H2

(d)

10M-ZnS

5M-ZnS

-0.6 -0.4 -0.2 0.0 0.2 0.40

5

10

15

20

25

30

C-2 (1

011 F

-2 c

m4 )

Potentail (V vs. SCE)

(c)

-0.6 -0.4 -0.2 0.0 0.2 0.40

5

10

15

20

25

30

C-2

(1011

F-2 c

m4 )

Potentail (V vs. SCE)

(a)

-0.6 -0.4 -0.2 0.0 0.2 0.40

5

10

15

20

25

30

C-2 (1

011 F

-2 c

m4 )

Potentail (V vs. SCE)

(b)

1M-ZnS

S12

Fig. S7

Fig. S7 (a) EIS and (b) photocurrent spectra under UV-light irradiation (λ ≤ 420 nm)

0 5 10 15 20 25 30 35 40 45 500

10

20

30

40

50

- Z" (O

hm)

Z' (Ohm)

1M-ZnS5M-ZnS10M-ZnS

(a)

100 120 140 160 180 200 220 240 260 280 300 320

Curre

nt (m

A cm

-2)

Time (second)

1M-ZnS 5M-ZnS 10M-ZnS

(b)

S13

Fig. S8

Fig. S8 SPV of (a) 1M-ZnS; (b) 5M-ZnS and (c) 10M-ZnS.

300 350 400 450 500 550 600

-4

-2

0

2

4

6

8

10(a)

Wavelegnth (nm)

Phot

ovol

tage

(M

)

300 350 400 450 500 550 600

-4

-2

0

2

4

6

8

10(c)

Wavelegnth (nm)

Phot

ovol

tage

(M

)

300 350 400 450 500 550 600

-4

-2

0

2

4

6

8

10(b)

Wavelegnth (nm)

Phot

ovol

tage

(M

)

S14

Fig. S9

Fig. S9 (a) Degradation curves and (b) reaction kinetic curves of Methylene Blue (MB)

solution under UV-light irradiation (λ ≤ 420 nm)

-30 -20 -10 0 10 20 30 40 50 600.0

0.2

0.4

0.6

0.8

1.0Light on

(a) MB

Dark

C/C 0

Time (min)

1M-ZnS5M-ZnS10M-ZnS

0 10 20 30 40 50 600.0

0.5

1.0

1.5

2.0

1M-ZnS5M-ZnS10M-ZnS

(b)

-ln (C

/C0)

Time (min)