Supporting Informationfor

Multicomponent N doped graphene coating Co@Zn heterostructures electrocatalystsas high efficiency HER electrocatalyst in alkaline electrolyte

Experimental details

The prepartion of 20%Pt/C electrode

10 mg of 20% Pt/C were dispersed in 5 mL of water ethanol mixtures (VH2O = 2450μL, VEtOH

= 2500μL) and 50 μL of 5% Nafion solution. The mixture was sonicated, to form a homogeneousink, and then dropped onto NF. Then, the 20%Pt/C were loaded onto NF with ~2.0 mg/cm2.

Electrochemical measurements

A standard three-electrode system with a potentiostat (CHI 660, Shanghai Chenhua Ltd. Co.)was used to take the HER performance. Hg/HgO and graphite rod were acted as the reference andcounter electrode, respectively. The NG@Co@Zn@NF was used as the working electrode(0.5×0.5 cm2). Linear sweep voltammetry (LSV) for HER were conducted in 1.0 M KOH with 5mV/s. The iR-correction was manually performed. Electrochemical impedance spectra (EIS) weretested from 10-2 to 106 Hz, with a sweep rate of 5 mV. And the potentials were referenced to areversible hydrogen electrode (RHE), by adding (0.098 + 0.059 pH) V.

10 20 30 40 50

ZIF-8 JCPDS#60-2542

In

tens

ity (a

. u.)

2 degree

ZIF-8@NF

(c)

Figure S1. SEM images of ZIF-8@NF(a and b); XRD patterns of ZIF-8@NF(c).

10 20 30 40 50 60 70 80

Co(OH)F JCPDS#50-0827

(c)

In

tens

ity (a

. u.)

2 degree

Co(OH)F@ZIF-8@NF

Figure S2. SEM images of Co(OH)F@ZIF-8@NF(a and b); XRD patterns ofCo(OH)F@ZIF-8@NF(c).

10 20 30 40 50 60 70 80

Co

3O

4@ZnO@NF

Co3O

4

NiO

Co3O

4 JCPDS#43-1003

NiO JCPDS#71-1179

(a)In

tens

ity (a

. u.)

2 degree

790 788 786 784 782 780 778 776Binding Energy (eV)

Inte

nsity

(a.u

.)

Y Observed Y Generated 1 2 3 Baseline Linear Bg

Co2p

(c)

779.3780.9784.6

Sat.

Co 3+

Co 2+

534 532 530 528 526

Absorbed O

O1s

(d)

Inte

nsity

(a.u

.)

Binding Energy (eV)

D2 D4 C1 C2 A

529.16530.53

Metal-O

1050 1045 1040 1035 1030 1025 1020 1015

Binding Energy (eV)

(e)

Inte

nsity

(a.u

.)

Zn 2p3/2

B

Zn 2p1/2

Zn2p

Figure S3. XRD patterns (a) and TEM images (b) of Co3O4@ZnO@NF; High-resolution XPSspectra of (c) Co 2p, (d) O 1s, and (e) Zn 2p peaks for Co3O4@ZnO@NF. The the peaks at bindingenergies (BE) of 779.3, 780.9 and 784.6 eV are assigned to Co3+, Co2+ and Sat. respectively. Thehigh-resolution O 1s region shows three peaks at 529.2 and 530.5 eV, assigned to the O-Co andabsorbed O species , respectively. The BEs of Zn 2p1/2 and Zn 2p3/2 appear at ~1045 and ~1022 eV,respectively.

Figure S4. SEM images of NG@Co@Zn@NF-850(a and b); TEM images ofNG@Co@Zn@NF-850(c and d).

10 20 30 40 50 60 70 802 degree

Ni(220)

Ni(200)

Ni(111)

C(002)

Bare NF NG@Co@Zn@NF-850

(a)

Inte

nsity

(a. u

.)

1050 1045 1040 1035 1030 1025 1020 1015

Zn 2p3/2

Binding Energy (eV)

Inte

nsity

(a.u

.)

C

(b)

Zn 2p1/2

Zn2p

536 534 532 530 528

Absorbed O

O-Co

Inte

nsity

(a.u

.)

Binding Energy (eV)

F2 Y Generated D1 D2 D3 Baseline Linear Bg % (7)

O-Zn

(c) O1s

Figure S5. XRD patterns of Bare NF and NG@Co@Zn@NF-850(a); High-resolution XPSspectra of (b) Zn 2p and (c) O1s peaks for NG@Co@Zn@NF-850.

Table S1. Comparison of electrocatalytic HER activity of other catalysts reported in recent years.

Catalyst Electrolyte CurrentDensity (j)

Overpotential at thecorresponding j

Tafel Slope Reference

NG@Co@Zn@NF-850

1.0 M KOH 10 mA·cm-2 34 mV 36.0 mV·dec-1 This work

Ni3N@CQD 1.0 M KOH 10 mA·cm-2 69 mV 108 mV·dec-1 [S1]Mo/Co@N-C 1.0 M KOH 10 mA·cm-2 157 mV 148 mV·dec-1 [S2]

NC@Vo-WON 1.0 M KOH 10 mA·cm-2 16 mV 33 mV·dec-1 [S3]Fe3C@Mo2C@N

-C1.0 M KOH 10 mA·cm-2 116 mV 43 mV·dec-1 [S4]

Ni3C@CNTs 1.0 M KOH 10 mA·cm-2 132 mV 49 mV·dec-1 [S5]NC@CuCo

Nitride1.0 M KOH 10 mA·cm-2 105 mV 76 mV·dec-1 [S6]

CoP@BCN 1.0 M KOH 10 mA·cm-2 215 mV 52 mV·dec-1 [S7]MoS2@N-CNTs 1.0 M KOH 10 mA·cm-2 110 mV 40 mV·dec-1 [S8]

CoP@CNT 1.0 M KOH 10 mA·cm-2 67 mV 54 mV·dec-1 [S9]NiNx@porous

carbon1.0 M KOH 10 mA·cm-2 147 mV 114 mV·dec-1 [S10]

Co2P@N,P-CNTs

1.0 M KOH 10 mA·cm-2 132 mV 103 mV·dec-1 [S11]

MoP@NPG 1.0 M KOH 10 mA·cm-2 126 mV 56 mV·dec-1 [S12]

Table S2. The details of fitting results for impedance. The Rs represent the solution resistance, Qand Rct represent the element of the catalyst/electrolyte interface and the charge transfer resistanceat catalyst/electrolyte interface, respectively.

Catalyst Rs Rct

NF 3.4 114.6

NG@Co@Zn@NF-850 3.2 4.7

0.15 0.20 0.25 0.30 0.35 0.40-20

-15

-10

-5

0

5

10

15

Potential （V vs. RHE）

C

urre

nt D

ensi

ty (m

A c

m-2

) 20mV/s 40mV/s 60mV/s 80mV/s 100mV/s

Figure S6. CV curves of NG@Co@Zn@NF-850 at various scan rates.

10 20 30 40 50 60 70 80

C(002)

2 degree

(c)

Inte

nsity

(a. u

.)

NG@Co@Zn@NF-350

Ni(220)

Ni(200)

Ni(111)

Figure S7. SEM images(a and b) and XRD patterns(c) of NG@Co@Zn@NF-350.

10 20 30 40 50 60 70 80

C(002)

2 degree

(c)

Inte

nsity

(a. u

.)

NG@Co@Zn@NF-550

Ni(220)

Ni(200)

Ni(111)

Figure S8. SEM images(a and b) and XRD patterns(c) of NG@Co@Zn@NF-550.

10 20 30 40 50 60 70 80

C(002)

(c)

2 degree

Inte

nsity

(a. u

.)

NG@Co@Zn@NF-750

Ni(220)

Ni(200)

Ni(111)

Figure S9. SEM images(a and b) and XRD patterns(c) of NG@Co@Zn@NF-750.

Table S3 The ratio of Co0+: Co3+: Co2+ for different catalysts.

Co0+ Co3+ Co2+

NG@Co@Zn-350 59.5 % 17.6 % 22.9 %

NG@Co@Zn-550 45.6 % 26.9 % 27.5 %

NG@Co@Zn-750 22.6 % 32.4 % 45.0 %

NG@Co@Zn-850 0 % 34.2 % 65.8 %

Zn2p3/2Zn2p1/2

Zn2p

Zn-350

Zn-550

1050 1040 1030 1020

NG@Co@Zn@NF-750

NG@Co@Zn@NF-550

NG@Co@Zn@NF-350

Binding Energy (eV)

(a)

Inte

nsit

y (a

.u.)

Y ObservedO1s

NG@Co@Zn@NF-350

NG@Co@Zn@NF-550

NG@Co@Zn@NF-750

Y Observed

536 534 532 530 528 526

(b)

Binding Energy (eV)

Inte

nsity

(a.u

.)

Y Observed

Figure S10. High-resolution XPS spectra of (a) Zn 2p and (b) O 1s peaks forNG@Co@Zn@NF-350, NG@Co@Zn@NF-550 and NG@Co@Zn@NF-750.

0.15 0.20 0.25 0.30 0.35 0.40

-5

0

5

Potential （V vs. RHE）

20mV/s 40mV/s 60mV/s 80mV/s 100mV/s

Cur

rent

Den

sity

(mA

cm

-2)

(a)

0.15 0.20 0.25 0.30 0.35 0.40

-5

0

5

20mV/s 40mV/s 60mV/s 80mV/s 100mV/s

Potential （V vs. RHE）

Cur

rent

Den

sity

(mA

cm

-2)

(b)

0.15 0.20 0.25 0.30 0.35 0.40

-10

-5

0

5

Potential （V vs. RHE）

Cur

rent

Den

sity

(mA

cm

-2)

20mV/s 40mV/s 60mV/s 80mV/s 100mV/s

(c)

Figure S11. CV curves of NG@Co@Zn@NF-350 (a), NG@Co@Zn@NF-550 (b) andNG@Co@Zn@NF-750 (c) at various scan rates.

10 20 30 40 50 60 70 80

(a)

2 degree

Inte

nsity

(a. u

.)

Before i-t testAfter i-t test

C(002)

290 288 286 284 282

Binding Energy (eV)

Inte

nsity

(a.u

.)

Y Observed Y Generated E6 E8 D2 D4 Baseline Linear Bg

C-Ox

C-N

sp3 C

sp2 C

(c)C

1s

283.8eV284.1 eV284.9 eV288.0 eV

408 406 404 402 400 398 396 394

Pyridine N

Oxidative N

N1s

Binding Energy (eV)

Inte

nsity

(a.u

.)

Y Observed Y Generated C1 C2 A E1 F1 B

(d)

Co-N

Pyrrolic N

Graphitic N

786 784 782 780 778 776

Peak shake

Co2p(e)

Binding Energy (eV)

Inte

nsity

(a.u

.)

Co3+

Sat.

Co2+

1050 1045 1040 1035 1030 1025 1020 1015

(f)

Inte

nsity

(a.u

.)

Binding Energy (eV)

Zn 2p3/2

Zn 2p1/2

Zn2p

536 534 532 530 528 526

Zn-O

O1s(g)

Binding Energy (eV)

Inte

nsity

(a.u

.)

D2 D4 1 2 3 Baseline Linear Bg

528.8530.6531.6

Co-O

Absorbed O

Figure S12. XRD patterns(a), SEM images(b) and High-resolution XPS spectra of (b) C 1s, (c) N1s, (d) Co 2p and (e) Ni 2p peaks after 90h i-t test for NG@Co@Zn@NF-850. The peaks ofhigh-resolution spectrum of C1s at binding energies (BE) of ~284.0, 284.1, 284.9 and 288.0 eV areassigned to sp2, sp3, C-N and C-Ox, respectively. The peaks of N 1s at 397.4, 398.6, ~400.0, 402.1and 406.7 eV are assigned to the pyridine N, Co-N, pyrrolic N, graphitic N and oxidative N,respectively. For high-resolution spectrum of Co 2p3/2, the peaks at binding energies (BE) of 779.3,780.9, and783.5 eV are assigned to Co3+, Co2+, and Sat. respectively, The high-resolution spectrumof Zn 2p shows Zn 2p1/2 and Zn 2p3/2 appear at ~1045 and ~1022 eV, respectively. Thehigh-resolution O 1s region (Figure S5c) shows three peaks at 528.8, 530.6 and 531.6 eV, assignedto the O-Zn, O-Co and absorbed O species , respectively.

Reference

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