S1

Supporting Information (SI)

Grain Boundaries Modified Uniformly-Conjoint

Metal/Oxides via Binder Strategy as Efficient

Bifunctional Electrocatalysts

Rongrong Zhang, Li Wang, Yu-Hang Ma, Lun Pan,* Ruijie Gao, Ke Li, Xiangwen Zhang, Ji-Jun Zou

Key Laboratory for Green Chemical Technology of the Ministry of Education, School of Chemical

Engineering and Technology, Tianjin University, Tianjin 300072, China.

Collaborative Innovative Center of Chemical Science and Engineering (Tianjin), Tianjin 300072,

China.

Corresponding author email address:

E-mail: panlun76@tju.edu.cn (L. Pan)

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2019

S2

Table of contents

Captions Page

Figure S1 XRD of CoNim-Gly and CoNi-Gly. S3

Figure S2 Schematic of melamine lie in interlamination of glyceric metal precursor (CoNim-Gly). S3

Figure S3 IR of CoNim-Gly and CoNi-Gly. S4

Figure S4 TG and DTG in argon flow of CoNim-Gly and CoNi-Gly. S4

Figure S5 TEM of CoNi. S5

Figure S6 HRTEM of CoNi. S5

Figure S7 TEM of CoNi-melamine with different Co/Ni ratio. Com and Nim are synthesized with

only one metal source of cobalt and nickel respectively. S5

Figure S8 XRD of CoNim and CoNi. S6

Figure S9 The linear combination fitting (LCF) of XANES for CoNi which main component is

metal. S6

Figure S10 The fine X-ray photoelectron spectroscopy (XPS) of CoNi and CoNim, fitting of O 1s. S7

Table S1 Elements concentration of CoNim and CoNi by XPS. S8

Figure S11 The XANES of Co K-edge for CoNim. S9

Figure S12 The XANES of Ni K-edge for CoNim. S9

Figure S13 XRD of Com and Nim. S10

Figure S14 RRDE tests for electron transfer number of Pt/C (a), IrO2 (b), and RuO2 (c). S11

Figure S15 LSV of IrO2 (a) and RuO2 (b) before and after 2000 cycle tests. S12

Figure S16 HRTEM of CoNim after OER stability test (washed from electrode). S13

Figure S17 HRTEM of CoNim after ORR stability test (washed from electrode) S13

Figure S18 Optimized adsorption structures of metal and metal oxides with (100) crystal faces. S14

Figure S19 Optimized OH adsorption structures of (100) crystal faces with composite clusters. S15

Figure S20 Optimized O2 adsorption structures of (100) crystal faces with composite clusters. S16

Figure S21 Galvanostatic (10 mA/cm2) charge-discharge cycling curves for Pt/C-IrO2 (a) and

CoNim (b). S17

Figure S22 (a,b) Co 2p and Ni 2p XPS spectra of CoNim surface after OER stability test. In Co 2p

and Ni 2p XPS, the surface Co, Co2+ and Ni, Ni2+ were oxidized to Co3+ and Ni3+. S18

// XAFS fit specific information. S19

// References S20

S3

Figure S1. XRD of CoNim-Gly and CoNi-Gly.

Figure S2. Schematic of melamine lie in interlamination of glyceric metal precursor (CoNim-Gly).

10 20 30 40 50 60 70 80

Inte

nsi

ty

2/degree

CoNim-Gly

CoNi-Gly

S4

Figure S3. IR of CoNim-Gly and CoNi-Gly.

0 200 400 600 800

40

50

60

70

80

90

100

w/

%

Temperature/ ℃

CoNi-Gly

CoNim-Gly

88.78%

55.24%

91.63 %

58.75 %

52.35%

57.22%

DT

G

Figure S4. TG and DTG in argon flow of CoNim-Gly and CoNi-Gly.

500 1000 1500 2000 2500 3000 3500 4000

0.0

0.1

0.2

0.3

0.4

0.5

0.6

OH

C-N

N-H

Tra

nsm

itta

nce

Wavenumbers /cm-1

CoNi-Gly

CoNim-Gly

N-H

S5

Figure S5. TEM of CoNi.

Figure S6. HRTEM of CoNi.

Figure S7. TEM of CoNi-melamine with different Co/Ni ratio. Com and Nim are synthesized with

only one metal source of cobalt and nickel respectively.

S6

Figure S8. XRD of CoNim and CoNi.

7700 7720 7740 7760

0.0

0.4

0.8

1.2

Co K-edge

no

rmal

ized

x

(E)

energy/eV

CoNi

LCF fitting

8% CoO

91% Co-foil

1% Co3O4

8300 8320 8340 8360 8380 8400 8420

0.0

0.4

0.8

1.2 Ni K-edge

photon enenrgy (eV)

A

bso

rpti

on (

a.u.)

CoNi

LCF fitting

6% NiO

94% Ni

residual

Figure S9. The linear combination fitting (LCF) of XANES for CoNi which main component is metal.

30 40 50 60 70 80 90

•

Ni 04-0850

Co 15-0806•

••

Inte

nsi

ty

2/degree

CoNi

CoNim

NiO 47-1049

Co3O

4 42-1467

CoO 48-1719

S7

540 538 536 534 532 530 528 526

CoNim

Inte

nsi

ty

Binding Energy/eV

O 1s

OV

OH2O

OOH-

OL

540 538 536 534 532 530 528 526

OV

OH2O

OOH-

O 1s

Inte

nsi

tyBinding Energy/eV

CoNi

OL

Figure S10. The fine X-ray photoelectron spectroscopy (XPS) of CoNi and CoNim, fitting of O 1s.

OL is oxygen-metal in lattice, OV is oxygen-metal in edge and interface, OOH- and OH2O are adsorbed

oxygen from air.1 Using lattice oxygen atoms (OL and OV) represent oxides content according to these

fittings.

S8

Table S1. Elements concentration of CoNim and CoNi by XPS.

Name CoNim CoNi

C 45.53 49.90

O 35.43 26.71

Co 10.30 11.27

Ni 8.74 12.12

S9

7700 7710 7720 7730 7740 7750 7760

0.0

0.5

1.0

1.5

norm

aliz

ed x

(E

)

energy/eV

CoNim

CoNi

Co

Co3O4

CoO

Co K-edge

Figure S11. The XANES of Co K-edge for CoNim.

8320 8330 8340 8350 8360 8370 8380 8390

0.0

0.4

0.8

1.2

1.6 Ni K-edge

no

rmal

ized

x

(E)

energy/eV

CoNim

CoNi

Ni

NiO

Figure S12. The XANES of Ni K-edge for CoNim.

S10

Information of different Co/Ni ratio samples

20 30 40 50 60 70 80 90

Inte

nsi

ty

/degree

Com

20 30 40 50 60 70 80 90

Inte

nsi

ty

/degree

Nim

Figure S13. XRD of Com and Nim.

S11

Figure S14. RRDE tests for electron transfer number of Pt/C (a), IrO2 (b), and RuO2 (c).

0.4 0.5 0.6 0.7 0.8 0.9 1.0

10 uA/cm2

Cu

rren

t

E/V (RHE)

1 mA/cm2

0

1

2

3

4

N

Pt(a)

1.3 1.4 1.5 1.6 1.7 1.8

Iring

Cu

rren

t

E/V (RHE)

20 mA/cm2

Idisk

0

1

2

3

4N

IrO2(b)

1.3 1.4 1.5 1.6 1.7 1.8

Iring

Curr

ent

E/V (RHE)

20 mA/cm2

Idisk

0

1

2

3

4

N

RuO2(c)

S12

Figure S15. LSV of IrO2 (a) and RuO2 (b) before and after 2000 cycle tests.

1.3 1.4 1.5 1.6 1.7 1.8

0

20

40

60

80

100

I/m

Acm

-2

E/V (RHE)

fresh

post 2000-cyclesIrO2(a)

1.3 1.4 1.5 1.6 1.7 1.8

0

20

40

60

80

100

I/m

Acm

-2

E/V (RHE)

fresh

post 2000-cyclesRuO2(b)

S13

Figure S16. HRTEM of CoNim after OER stability test (washed from electrode).

Figure S17. HRTEM of CoNim after ORR stability test (washed from electrode).

S14

Figure S18. Optimized adsorption structures of metal and metal oxides with (100) crystal faces.

S15

Figure S19. Optimized OH adsorption structures of (100) crystal faces with composite clusters.

S16

Figure S20. Optimized O2 adsorption structures of (100) crystal faces with composite clusters.

S17

Figure S21. Galvanostatic (at 10 mA/cm2) charge-discharge cycling curves for Pt/C-IrO2 (a) and

CoNim (b).

0.0 0.5 1.0 1.5 2.0 2.5 3.0

1.2

1.4

1.6

1.8

2.0

Pote

nti

al/V

Time/h

Pt/C-IrO2 @10 mA/cm2(a)

0.0 0.5 1.0 1.5 2.0 2.5 3.0

0.6

0.9

1.2

1.5

1.8

2.1

Pote

nti

al/V

Time/h

CoNim @10 mA/cm2(b)

S18

Figure S22. (a,b) Co 2p and Ni 2p XPS spectra of CoNim surface after OER stability test. In Co 2p

and Ni 2p XPS, the surface Co, Co2+ and Ni, Ni2+ were oxidized to Co3+ and Ni3+.

810 805 800 795 790 785 780 775

Co

Co2+

Co 2p1/2

sat.

sat. Co

3+

Inte

nsi

ty

Binding Energy/eV

Co 2p3/2

CoNim-fresh

CoNim-after OER stability test (a)

890 885 880 875 870 865 860 855 850

Ni3+

Ni2+

CoNim-fresh

CoNim-after OER stability test (b)

sat. sat.

Ni 2p1/2

Ni 2p3/2

Inte

nsi

ty

Binding Energy/eV

Ni

S19

XAFS fit specific information.

Three paths from 1.10 Å to 2.85 Å (Co-O of Co3O4, Co-O of CoO, and Co-Co of Co metal) were

used in Co k-edge adsorption spectrum fit, and three paths from 1.25 Å to 3.00 Å (Ni-O of NiO, Ni-

Ni of Ni metal, Ni-Ni of NiO) were used in Ni k-edge adsorption spectrum fit. According to the

principle and results of LCF, the following standard EXAFS formula can be used in absorption

spectrum of mixed substances:

(k) =∑𝑁𝑗𝑆0

2𝑓𝑗(𝑘)

𝑘𝑅𝑗2

𝑗

𝑒−2𝑘2𝑗

2𝑒−2𝑅𝑗 𝑗(𝑘)⁄ sin[2𝑘𝑅𝑗 + 𝑗(𝑘) + 2

𝐶(𝑘)]

j=1, 2, 3 represent three paths mentioned above. Nj denotes the total number of atoms in the j-th

shell. S02 is the amplitude reduction factor. R is the distance between the absorbing and scattering

atoms. (k) is the mean free path of the excited photoelectron. f(k) and δ(k) are the backscattering

amplitude and scattering phase shift of the scattering atom, respectively. φC(k) is phase-shift of the

absorbing atom. 2 known as the Debye-Waller factor, is the mean square variation in the interatomic

distance R and 𝑒−2𝑘2𝑗

2 term accounts for the effects of dynamic (thermal) vibration and

configuration (structural) disorder which smear out the EXAFS oscillations at high k region. The N

values obtained by fitting are multiplied by the ratio of the substance from LCF to obtain the atomic

coordination number of each substance in the mixture.2

S20

Reference

1. Xu, L.; Jiang, Q.; Xiao, Z.; Li, X.; Huo, J.; Wang, S.; Dai, L., Plasma-Engraved Co3O4 Nanosheets

with Oxygen Vacancies and High Surface Area for the Oxygen Evolution Reaction. Angew. Chem. Int.

Ed. 2016, 55 (17), 5277-81.

2. Sun, Z.; Yan, W.; Yao, T.; Liu, Q.; Xie, Y.; Wei, S. XAFS in Dilute Magnetic Semiconductors. Dalton

T. 2013, 42, 13779-13801.