Supplementary Material

Ripple-like NiFeCo sulfides on nickel foam derived from in-

situ sulfurization of precursor oxides as efficient anodes for

water oxidation

Yong-Ming Chai a, Xiao Shang a, Zi-Zhang Liu a, b, Bin Dong*a, b, Guan-Qun Han a, b,

Wen-Kun Gao a, b, Jing-Qi Chi a, Kai-Li Yan a, Chen-Guang Liu *a

a State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China),

Qingdao 266580, PR China

b College of Science, China University of Petroleum (East China), Qingdao 266580, PR China

* * Corresponding author. Email: dongbin@upc.edu.cn (B. Dong), cgliu@upc.edu.cn (C.-G. Liu)

Tel: +86-532-86981376, Fax: +86-532-86981787*

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Fig. S1 TEM images of (a) NiFeCo/NF, (b) sNiFeCo/NF and (c) sNiFeCo-Fe/NF.

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Fig. S2 SEM mapping and EDX spectra of (a, b) NiFeCo/NF, (c, d) sNiFeCo/NF and

(e, f) sNiFeCo-Fe/NF.

Fig. S2 SEM mapping and EDX spectra of (a, b) NiFeCo/NF, (c, d) sNiFeCo/NF and

(e, f) sNiFeCo-Fe/NF.

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Fig. S3 N2 adsorption-desorption isotherms with corresponding pore size distribution

(insertion) of all samples.

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Potentials conversion from vs. SCE to vs. RHEThe potentials conversion from vs. SCE to vs. RHE are based on the following

equations:

pH (1.0 M KOH) = 14

SCE (saturated KCl) vs. RHE = 0.244 V

E (vs. RHE) = E (vs. SCE) + 0.244 V + (0.059 V) pH = E (vs. SCE) + 1.07 V

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Table. S1 Elemental values of fitted equivalent circuit corresponding to EIS spectra.

Samples Rs/Ω Rct/Ω

NiFeCo/NF 1.6 3.9

sNiFeCo/NF 1.8 1.4

sNiFeCo-Fe/NF 1.7 2.7

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Calculation of electrochemically active surface area (ECSA)

Based on previous work [1, 2], the value of ECSA can be determined through the

following equations:

ECSA=Cdl/Cs (1)

RF=ECSA/GSA (2)

where Cdl is the measured double layer capacitance in 1.0 M KOH (mF), Cs is the

specific capacitance (Cs = 0.04 mF cm−2 in 1.0 M KOH) and GSA is the geometric

surface area of as-prepared sample (2.00 cm2).

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Fig. S4 CVs of (a) NiFeCo/NF, (b) sNiFeCo/NF and (c) sNiFeCo-Fe/NF for

measuring the corresponding values of ECSA.

Table S2 Calculated ECSA values of NiFeCo/NF, sNiFeCo/NF and sNiFeCo-Fe/NF.

SampleCdl, Cs, ECSA,

cm2

GSA,

cm2RF

mF mF cm-2

NiFeCo/NF 2.3 0.04 57.5 2.00 28.8

sNiFeCo/NF 22.3 0.04 557.0 2.00 278.5

sNiFeCo-Fe/

NF18.4 0.04 459.0 2.00 229.5

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References

[1] C. C. L. McCrory, S. Jung, J. C. Peters, T. F. Jaramillo, Benchmarking

heterogeneous electrocatalysts for the oxygen evolution reaction, J. Am. Chem. Soc.

135 (2013) 16977-1691.

[2] X. Lu, C. Zhao, Electrodeposition of hierarchically structured three-dimensional

nickel-iron electrodes for efficient oxygen evolution at high current densities, Nat.

Commun. 6 (2015) 7616-7623.

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