supplementary information fep@nc towards …1 supplementary information potential-driven surface...
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Supplementary Information
Potential-driven surface active structure rearrangement over
FeP@NC towards efficient electrocatalytic hydrogen evolutionFumin Tang,1 Hui Su,1 Xu Zhao,1 Hui Zhang,1 Fengchun Hu,1 Peng Yao,2 Qinghua Liu1, and Weiren Cheng1,*
1National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China2Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, Anhui, P. R. China
*E-mail: [email protected]
Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics.This journal is © the Owner Societies 2019
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S1. Calibration of potential vs Ag/AgCl to RHE.1
the relation between Ag/AgCl and RHE potential can be calibrated in
the high purity H2 saturated 0.5 M H2SO4 electrolyte with a Pt wire as the
working electrode. With a scan rate of 1 mV/s, the average potential,
where the current density started to came across X axis (becoming zero)
in CV curves, was regarded as the thermodynamic potential for the
hydrogen electrode reactions (Figure S2).
S2. Calculation of jECSA and TOF (Figure S9).2,3
(1);𝐸𝐶𝑆𝐴=
𝐶𝑑𝑙𝐶𝑠
(2);𝑗𝐸𝐶𝑆𝐴=
𝑗 × 𝑆𝐸𝐶𝑆𝐴
(3).𝑇𝑂𝐹=
𝑗 × 𝑆2𝑛𝐹
ECSA is short for electrochemical active surface area;
Cdl and Cs is double layer capacitance and specific capacitance of samples,
and Cs is assumed to 35 μC/cm2 according to previous report3.
j, S, F and n is the current density under given overpotential, the surface
area of the electrode, Faraday constant and the mole number of active
metal atoms for the electrode.
3
Figure S1. LSV curves in 0.5 M H2SO4 for FeP@NC synthesized under
different temperatures.
4
-0.30 -0.25 -0.20 -0.15 -0.10
-0.004
-0.003
-0.002
-0.001
0.000j (
A)
Potential (V vs Ag/AgCl)
-0.18 V
Figure S2. CV curve of Pt wire in 0.5 M H2SO4 electrolyte.
Figure S3. Details of the device in in-situ XAS measurement.
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5 nm200 nm
(a) (b)
0.24 nm
Figure S4. SEM and HRTEM images of FeP particles.
0 2 4 6 8 10 12 14 16-2
-4
-6
-8
-10
-12
-14
FeP@NC FeP particles
j (m
A/c
m2 )
Time (h)
Figure S5. Chronopotentiometric measurements with an initial current
density of 10 mA/cm2 for FeP@NC at -0.135 VRHE and for FeP particles
at -0.495 VRHE.
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0 1000 2000 3000
300
600
900
1200 FeP particles FeP@NC
- Im
Z (
)
Re Z ()
Figure S6. Nyquist plots of FeP particles and FeP@NC at -0.15 VRHE in a
large scale.
406 404 402 400 398 396 394
Inte
nsity
(a.u
.)
Energy (eV)
Pyridinic-N
N 1s Pyrrolic-N
Figure S7. Deconvolution of N 1s XPS spectra for FeP@NC.
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-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15-0.08
-0.06
-0.04
-0.02
0.00
0.02
0.04m
A/c
m2
V vs Ag/AgCl
20 mV/s 40 mV/s 80mV/s 120 mV/s 160 mV/s
-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15
-0.8-0.6-0.4-0.20.00.20.40.60.8 160 mV/s
120 mV/s80mV/s
20 mV/s
mA
/cm
2
V vs Ag/AgCl
40 mV/s
(a) (b)
Figure S8. Cyclic voltammetry curves of (a) FeP particles and (b)
FeP@NC.
85 135 1850
2
4
6
8
10
12
14
FeP particles
TOF
(10-3
·s-1
)
Overpotential (mV)
0
50
100
150
200
250
300
350
400 FeP@NC
TOF
(10-3
·s-1
)85 135 185
0
4
8
12
16
20
24
j EC
SA (m
A/c
m2 )
Overpotential (mV)
FeP@NC FeP particle
(a) (b)
Figure S9. (a) JECSA, and (b) TOF comparison of FeP@NC and FeP
particles under different overpotentials in 0.5 M H2SO4.
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-0.12
-0.10
-0.08
-0.06
-0.04
-0.02
0.00
0.02
2.5 mA/cm2
0 mA/cm2
AfterBefore
Pote
ntia
l (V
vs R
HE)
Test SequenceDuring
0 mA/cm2
Figure S10. Working condition of work electrode during in-situ XAS
measurement.
7112 7113 7114 7115 7116 7117
-0.04
-0.02
0.00
0.02
0.04
0.06
2nd d
eriv
ativ
e
Energy (eV)
Before HER After HER During HER
7120 7140 7160 71800.0
0.2
0.4
0.6
0.8
1.0
1.2
XA
NES
Energy (eV)
Before HER After HER During HER
Figure S11. (a) XANES and (b) 2nd derivative curves of pre-edge region.
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0 2 4 6 8 10
-6
-4
-2
0
2
4
6
1s
Ener
gy (e
V)
D.O.S
3dz2
Figure S12. DOS calculation of 3dz2 orbits in different surface structure.
100 nm
(a) (b)
30 35 40 45 50 55 60 65
Inte
nsity
2(Degree)
FeP pdf.78-1443
Before HER
After HER
(c)
5 nm
Figure S13. (a) TEM, (b) HRTEM images and XRD patterns of
FeP@NC after long-time HER measurement.
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536 534 532 530 528
Inte
nsity
(a.u
.)
Binding Energy (eV)
Before HER
After HERAfter HER
H2O/OH Fe-OP-O
C-OO 1s
Figure S14. XPS comparison of O 1s for FeP@NC.
Table S1. The EXAFS fitted results for structure parameters around Fe
atoms.
Paths N σ2 (10-3) ΔE(eV) ΔR(Å)
Before HER
Fe-P 5.6 6.4 -1.84 0.024
Fe-O <0.05
During HER
Fe-P 5.8 5.3 -1.55 0.039
Fe-O 0.85 5.5 -2.12 -0.04
After HER
Fe-P 5.6 6.3 -1.84 0.024
Fe-O 0.23 5.0 -3.25 -0.04
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Table S2. The ratio of different bonds according to Figure S14.
Fe-O P-O C-O H2O/OH
Before HER 12.0 % 32.9 % 52.7 % 2.4 %
After HER 22.1 % 24.9 % 49.7 % 3.3 %
Table S3. Summary of HER performance for recent typical TMP electrocatalysts in 0.5 M H2SO4 electrolyte. (Stability is defined as the time when current density decays to its’ 90 %)
η@10 mA/cm2
(mV)
Tafel slope
(mV/dec)Stability Ref.
FeP@NC 135 78 >15 h This work
FeP 240 67 - Chem. Commun., 2013, 49, 6656.
FeP/NCNSs 114 64 - ACS Sustain. Chem. Eng., 2018, 6, 11587-
11594.
FeP nanowires 96 39 < 1 h Chem. Commun., 2016, 52, 2819–2822.
CoP nanorod bundle arrays/Ti
203 40 ~10 h Electrochem. Commun., 2015, 56, 56–60.
CoP@BCN-1 87 46 < 10 hAdv. Energy Mater., 2017, 7, 1601671.
Ni-P@Carbon fiber paper
98 58.8 - Adv. Funct. Mater., 2016, 26, 4067–4077.
Ni3P porous hollow
85 50 > 11 h J. Mater. Chem. A, 2016, 4, 10925–10932.
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172 62 < 6 h RSC Adv., 2015, 10290–10295.
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143 57 - Nanoscale, 2016, 8,8500–8504 .
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124 58 < 10 h Appl. Catal. B: Environ., 2016, 196, 193–198
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References
1. Li Y.Y., J. Am. Chem. Soc., 2011, 133, 7296-7299.
2. Liu B. et al, Adv. Mater., 2018, 30, 1803144.
3. McCrory C. C. L., J. Am. Chem. Soc., 2013, 135, 16977−16987.