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Electronic Supplementary Information

Experimental Section

Materials: Ni(NO3)2·6H2O was purchased from Aladdin Ltd. in Shanghai.

Zn(NO3)2·6H2O, urea and Hydrochloric acid (HCl) were purchased from Beijing

Chemical Works. Nickel foam (NF) was purchased from Shenzhen Green and

Creative Environmental Science and Technology Co. Ltd. Ethanol was purchased

from Aladdin Ltd. (Shanghai, China). Nafion (5 wt%) was purchased from Sigma-

Aldrich. All the reagents were used as received. The water used throughout all

experiments was purified through a Millipore system.

Synthesis of precursor on Ni foam: In a typical procedure, Ni(NO3)2·6H2O (1

mmol, 0.291g), Zn(NO3)2·6H2O, (0.1 mmol, 0.0298g) and urea (10 mmol, 0.6g)

were dissolved in 40 mL distilled water and stirred to form a clear solution. Then

the above solution and a piece of cleaned Nickel foam (2 cm × 3 cm) were

transferred to a 50 mL Teflon-lined stainless-steel autoclave and maintained at 120

°C for 7 h. After the autoclave cooled down naturally, the resulting NF was taken

out and washed with distilled water and ethanol several times, followed by drying

2 h at 60 ºC.

Synthesis of ZnxNi1-xS on Ni foam: The precursor loaded Ni foam was immersed in

40 mL 0.2 mol L–1 Na2S solution in a Teflon-lined stainless-steel autoclave (60 mL

capacity). Then the autoclave was heated in an oven at 120 °C for 4 h. After that, the

autoclave was cooled down to room temperature naturally. The Ni foam was

repeatedly washed with deionized water and ethanol in sequence, and dried in vacuum

at 50 °C for 3 h.

Characterizations: The XRD patterns were obtained from a LabX XRD-6100 X-ray

diffractometer with Cu Kα radiation (40 kV, 30 mA) of wavelength 0.154 nm

(SHIMADZU, Japan). SEM images were collected on a XL30 ESEM FEG scanning

electron microscope at an accelerating voltage of 20 kV. TEM images were collected

on a HITACHI H-8100 electron microscopy (Hitachi, Tokyo, Japan) with an

accelerating voltage of 200 kV. XPS measurements were performed using an

Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2017

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ESCALABMK II X-ray photoelectron spectrometer with the exciting source of Mg.

Electrochemical measurements: Electrochemical measurements were performed

with a CHI 660E electrochemical analyzer (CH Instruments, Inc., Shanghai) in a

standard three-electrode system using Zn-Ni3S2/NF as the working electrode, a

platinum wire as counter electrode and Hg/HgO as the reference electrode. The

potentials reported in this work were calibrated to RHE, using the following equation:

E (RHE) = E (Hg/HgO) + (0.098 + 0.059 pH) V. Polarization curves were obtained

by linear sweep voltammetry with a scan rate of 2 mV s-1. All experiments were

carried out at 25 °C.

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Fig. S1. SEM image of bare NF.

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Fig. S2. LSV curves of Zn1.5%-Ni3S2/NF, Zn3%-Ni3S2/NF, Zn9%-Ni3S2/NF and Zn12%-Ni3S2/NF for

OER with a scan rate 5 mV s-1 in 1.0 KOH.

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Fig. S3. LSV curves of Zn-Ni3S2/NF in 30% KOH with 2 mv s-1.

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Fig. S4. LSV curves for Zn-Ni3S2/NF in 1.0 M KCi (pH=8.3) and 1.0 M PBS solutions (pH=7)

with a scan rate of 5 mv s-1 for OER with iR correction.

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Fig. S5. SEM images for Zn-Ni3S2/NF after stability test.

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Fig. S6. Cyclic voltammograms of (a) Ni3S2/NF (b) Zn-Ni3S2/NF in the non-faradaic capacitance

current range at scan rates of 60, 100, 140, 180, 220, 260 and 300 mV s-1. (c) and (d) the The

capacitive currents at certain potential (0.07 V vs. HgO/HgO) as a function of scan rate for

Ni3S2/NF and Zn-Ni3S2/NF.

Table S1. Comparison of the OER activity for Zn-Ni3S2/NF with several recently reported

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catalysts.

Catalyst j (mA cm-2) η (mV) Electrolyte Ref.

Ni3S2/AT-NF 30 480 0.1 M KOH 1

ALD NiSX 10 372 1.0 M KOH 2

Ni3S2@Ni 20 350 0.1 M KOH 3

NiS/Ni foam 100 350 1.0 M KOH 4

NiFe LDH/NF 100 390 1.0 M KOH 5

Ni-P/Ni 100 374 1.0 M KOH 6

Ni3Se2/Cu foam 100 388 1.0 M KOH 7

NiCo2O4 100 430 1.0 M KOH 8

Ni-B/Ni 100 360 1.0 M KOH 9

Ni2.3%-CoS2/C 100 370 1.0 M KOH 10

NiCo2S4 NA/CC 100 340 1.0 M KOH 11

Ni/Ni3N foam 100 470 1.0 M KOH 12

CoNi SUNOE 10 450 1.0 M KOH 13

NiFe SUNOE 10 550 91.0 M KOH 13

NiCo LDH 10 367 1.0 M KOH 14

Fe-Ni oxide 10 >375 1.0 M KOH 15

NiCo2O4 NNs/FTO 10 565 1.0 M KOH 16

β-Ni(OH)2 10 444 1.0 M KOH 17

NiOOH 10 525 1.0 M KOH 18

NiO 10 >470 1.0 M KOH 19

Ni-Co-S/CF 100 363 1.0 M KOH 20

TiN@Ni3N 10 350 1.0 M KOH 21

Ni3S2/NF 50 470 1.0 M KOH 22

uFe/Ni3S2/NF 100 350 1.0 M KOH 23

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Ni3S2/PNF 100 580 1.0 M KOH 24

CdS/ Ni3S2/PNF 100 550 1.0 M KOH 24

Zn-Ni3S2/NF 100 330 1.0 M KOH This work

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