Appendix A.

Supplementary Information

Metal-Organic Frameworks Derived Reverse-

Encapsulation Co-NC@Mo2C Complex for

Efficient Overall Water Splitting

Qirui Lianga, Huihui Jina, Zhe Wangb, Yuli Xiong*c, Shuai Yuana, Xianci Zengb, Daping He*a,b

and Shichun Mu*a

a State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,

Wuhan University of Technology, Wuhan 430070, China.

b Hubei Engineering Research Center of RF-Microwave Technology and Application, Wuhan

University of Technology, Wuhan 430070, China.

c School of Electronic and Electrical Engineering, Wuhan Textile University, Wuhan 430200,

China.

*Address corresponding to: hedaping@whut.edu.cn, ylxiong@wtu.edu.cn, msc@whut.edu.cn

Figure S1 SEM images of ZIF-67.

Figure S2 TEM images of ZIF-67.

Figure S3 SEM images of ZIF-67 after grinding with ammonium molybdate tetrahydrate.

Figure S4 SEM images of Co-NC@Mo2C.

Figure S5 (a) TEM and (b) HAADF-STEM images of Co-NC@Mo2C.

Figure S6 HRTEM image of Co-NC@Mo2C

Figure S7 EDX spectrum of Co-NC@Mo2C.

Figure S8 SEM images of Co-NC.

Figure S9 TEM images of ZIF-8.

Figure S10 TEM images of NC@Mo2C.

Figure S11 XRD patterns of Co-NC@Mo2C and some contrast samples.

Figure S12 Raman spectrum of Co-NC@Mo2C.

Figure S13 XPS spectra of Co-NC@Mo2C: (a) survey, (b) C 1s, (c) N 1s, (d) O 1s.

Figure S14 HER polarization curves of Co-NC@Mo2C at different temperatures in 1.0 M

KOH aqueous solution.

Figure S15 Time-dependent current density curves for Pt/C at constant potentials for 25 h

and corresponding polarization curves before and after 1000 CV cycles in (a) 1.0 M KOH

and (b) 0.5 M H2SO4 aqueous solution.

Figure S16 XPS spectra of Co-NC@Mo2C after HER stability test.

Figure S17 XRD patterns of Co-NC@Mo2C before and after HER stability test.

Figure S18 SEM image of the Co-NC@Mo2C after HER stability test.

Figure S19 (a, b, c) CVs with different rates from 20 to 120 mV s−1 in the region of -0.5 ~ -

0.6 V for Co-NC@Mo2C, Co-NC, NC@Mo2C in 1.0 M KOH aqueous solution respectively.

(d) The capacitive currents at -0.55 V with different scan rates.

Figure S20 Time-dependent current density curves for (a) IrO2 and (b) IrO2-Pt/C at constant

potentials for 20 h and corresponding polarization curves before and after 1000 CV cycles.

Figure S21 Comparison with selected state-of-the-art (a, b) HER and (c) OER electrocatalysts.

Figure S22 Gas collection device of water splitting.

Table S1 Inductively coupled plasma results for Co and Mo contents in Co-NC@Mo2C.

Element W(B)%Co 27.43Mo 62.95

Table S2 The surface element content of Co-NC@Mo2C measured by XPS measurements.

Element Content (at.%)C 19.64N 28.57O 31.45Co 6.94Mo 13.41

Table S3 Tafel slope (mV dec-1) of several catalysts in this experiment.

HER in 1.0 M KOH HER in 0.5 M H2SO4 OER in 1.0 M KOHCo-NC@Mo2C 65 60 61

Co-NC 172 267 121

NC@Mo2C 68 65 176

NC 277 319 228

Commercial Mo2C

122 180 96

Commercial Pt/C 69 34 /

Commercial Ir2O / / 88

Table S4 Comparison of HER performance in acid/alkaline media for Co-NC@Mo2C with

other reported electrocatalysts.

Catalysts Electrolytes η@10mA cm-2(mV)

Catalyst loading (mg cm-2)

Ref.

Co-NC@Mo2C 0.5 M H2SO4

1.0 M KOH14399

0.83 This work

MoCN-3D 0.5 M H2SO4

1.0 M KOH89122

0.26 Asia. Mater. 2016, 8, e293-e293.

Co-C-N 0.5 M H2SO4

1.0 M KOH138178

- J. Am. Chem. Soc. 2015, 137, 15070-15073.

CoP/CC 0.5 M H2SO4

1.0 M KOH67209

0.92 J. Am. Chem. Soc.2014, 136, 7587-7590.

Co, N/3DG-2 0.5 M H2SO4 141 0.28 J. Power Sources 2017, 363, 260-268.

CoP/CNT 0.5 M H2SO4 122 0.285 Angew. Chem. Int. Ed. 2014, 53, 6710-6714.

Co-NCNT/CC 0.5 M H2SO4

1.0 M KOH78180

3.4 ChemSusChem2015, 8, 1850-1855.

CoNC/GD 0.5 M H2SO4

1.0 M KOH340284

- ACS. Appl. Mater. Inter.2016, 8, 31083-31091.

Zn0.30Co2.70S4 0.5 M H2SO4

1.0 M KOH8085

0.285 J. Am. Chem. Soc. 2016, 138, 1359-1365.

MoCx/C 0.5 M H2SO4

1.0 M KOH135150

0.45 Small Methods2018, 2, 1700353.

Mo2C/GCSs 0.5 M H2SO4 200 0.36 ACS. Catal.2014, 4, 2658-2661.

Mo2CTx 0.5 M H2SO4 283 0.1 ACS. Energy. Lett.2016, 1, 589-594.

Mo2C@2D-NPCs

0.5 M H2SO4

1.0 M KOH8645

- ACS. Nano2017, 11, 3933-3942.

Mo2C@NC 0.5 M H2SO4

1.0 M KOH12460

0.28 Angew. Chem. Int. Ed. 2015, 54, 10752-10757.

uf-Mo2C/CF 0.5 M H2SO4

1.0 M KOH184185

0.25 Small Methods 2018, 2, 1700396.

Mo2C QD/NGCL

0.5 M H2SO4

1.0 M KOH136111

2.0 Chem. Commun.2016, 52, 12753-12756.

Co-P/NC 1.0 M KOH 154 0.283 Chem. Mater.2015, 27, 7636-7642.

Co-P 1.0 M KOH 94 - Angew. Chem. Int. Ed.2015, 54, 6251-6254.

Table S5 The surface elemental content of Co-NC@Mo2C after HER stability test measured

by XPS measurements.

Element Content (at.%)C 18.16N 10.76O 55.72Co 5.29Mo 10.07

Table S6 Comparison of OER performance in alkaline media for Co-NC@Mo2C with other

reported electrocatalysts.

Catalysts Electrolytes η@10mA cm-2(mV)

Catalyst loading(mg cm-2)

Ref.

Co-NC@Mo2C 1.0 M KOH 347 0.83 This work

Co-P/NC 1.0 M KOH 319 0.283 Chem. Mater. 2015, 27, 7636-7642.

Co-P 1.0 M KOH 345 - Angew. Chem. Int. Ed. 2015, 54, 6251-6254.

NiCoP/C 1.0 M KOH 330 0.25 Angew. Chem. Int. Ed. 2017, 56, 3897-3900.

Co NPs 0.1 M KOH 390 0.2 J. Am. Chem. Soc. 2015, 137, 7071-7074.

ZnCo2O4 1.0 M KOH 390 - J. Phys. Chem. Lett. 2014, 5, 2370-2374.

Co3O4 0.1 M KOH 300 - Angew. Chem. Int. Ed. 2016, 55, 5277-5281.

NCO–HNSs 1.0 M NaOH 340 - Adv. Energy. Mater. 2015, 5, 1500091.

Co3O4_EC_0.50 1.0 M NaOH 377 - ACS. Appl. Mater. Inter.

2015, 7, 24550-24555.

HFC Co3O4 2.0 M KOH 409 0.14 ACS. Appl. Mater. Inter. 2015, 7, 20322-

20331.

Ni-Co2-O HNSs 0.1 M KOH 362 0.2 Chem. Commun. 2015, 51, 7851-7854.

Co-S/Ti mesh 1.0 M KOH 361 - Electrochem.Commun. 2015, 60, 92-96.

CFO/rGO 1.0 M KOH 340 - ChemSusChem 2015, 8, 659-664.

CeO2/Co3O4-2 0.3 M KOH 386 - J. Mater. Sci-Mater. El. 2016, 27, 5294-

5302.

Fe1Co1-ONS 0.1 M KOH 308 0.36 Adv. Mater. 2017, 29. 1703614.

NiCo2O4 0.1 M KOH 340 0.25 Dalton Trans. 2015, 44, 4148-4154.

Ni-Fe-Co 0.1 M KOH 310 0.25 ACS. Catal. 2015, 6, 155-161.

BCFSn-721 0.1 M KOH 450 - Adv. Sci. 2016, 3, 1500187.

Table S7 Comparison of catalytic performance (mV) at the current density of 10 mA cm–2 in

1.0 M KOH aqueous solution for Co-NC@Mo2C with other relevant bifunctional

electrocatalysts reported in recent years.

Catalysts HER(mV)

OER(mV)

Water Splitting(V)

Ref.

Co-NC@Mo2C

Cu@CoFe LDH

Fe-Co

PO-Ni/Ni-N-CNFs

Co/NBC

N-NiMoO4/NiS2

Ni–Co–P HNBs

99

171

163

262

117

99

107

347

240

283

420

302

283

270

1.685

1.681

1.68

1.69

1.68

1.60

1.62

This work

Nano Energy 2017, 41, 327–336

Nano Energy 2017, 38, 576–584

Nano Energy 2018, 51, 286–293

Adv. Funct. Mater. 2018, 28, 1801136.

Adv. Funct. Mater. 2018, 1805298.

Energy Environ. Sci.2018, 11, 872