Figure S 3-1. (a-b), (d-e) and (g-h) are the SEM images of the bare NF, NiCo hydroxide /NF and NiFe LDH/NF, respectively, whereas the insets show high-resolution images. (c), (f) and (i) are the corresponding EDX spectra of bare NF, NiCo hydroxide /NF and NiFe LDH/NF, respectively.
Figure S 3-2. EDX spectra of the as-prepared (a) NiCoP/NF and (b) NiFe LDH@NiCoP/NF.
Table S 3-1. EDX results of the as-prepared electrocatalysts.
Samples Ni
(atom%) O (atom%)
Co (atom%)
P (atom%)
Fe (atom%)
K (atom%)
Bare NF 98.96 1.04 -- -- -- --
NiCo hydroxide/NF 17.00 57.13 25.87 -- -- --
NiCoP/NF 53.90 16.68 12.30 17.29 -- --
NiFe LDH/NF 23.05 71.27 -- -- 5.69 --
NiFe LDH@NiCoP/NF 33.07 21.61 21.99 22.31 1.02 --
NiFe LDH@NiCoP/NF post HER 32.62 49.57 5.98 10.29 0.74 0.81 NiFe LDH@NiCoP/NF post OER 16.16 68.09 4.88 5.98 0.55 4.35
Figure S 3-3. The equivalent circuit diagram used for analysis of the EIS curves measured for the OER and the HER
Table S 3-2. Summary of the EIS results fitted to the equivalent circuit board as shown in Figure S 3-3.
Sample Reaction Rct (Ω) R1 (Ω) CPE
Y0 (μMho) n
Bare NF
HER 34.5 1.20 0.625 0.86
OER 5.39 1.11 0.052 0.811
NiCoP/NF
HER 6.01 1.10 2.29 0.866
OER 1.39 1.16 1.15 0.994
NiFe LDH/NF
HER 20.80 1.15 1.27 0.851
OER 0.63 1.10 0.625 0.555
NiFe LDH@NiCoP/NF
HER 2.77 1.20 9.16 0.824
OER 0.41 1.10 2.08 0.613
Table S 3-3. Comparison of the HER performance of our NiFe LDH@NiCoP/NF heterostructure to other reported electrocatalysts in alkaline media.
Catalyst
Electrolyte
（KOH）
η10a
(mV)
Tafel slope (mV/dec)
Durability
(h) Ref.
NiFe LDH@NiCoP/NF 1 M 120 88.2 100 This work
NiFe/NiCo2O4/NFb 1 M 105 88 10 [S1]
NiFe LDH/NiCo2O4/NF 1 M 192 59 10 [S2]
NiFe LDH@NiCo2S4/NFb 1 M 200 101.1 12 [S3]
MoS2/Ni3S2/NFb 1 M 110 83 10 [S4]
NiO@Ni@Carbon fiber 1 M 153 84 24 [S5]
EG/Co0.85Se/NiFe LDHb 1 M 260 125 10 [S6]
NiCo2Px/Carbon feltb 1 M 58 34.3 30 [S7]
NiFe LDH/NF 1 M 210 58.9 10 [S8]
Ni5P4/Ni foil 1 M 150 53 20 [S9]
Ni(OH)2/NF 1 M 172 140 24 [S10]
Ni3S2/NF 1 M 223 -- 200 [S11]
Ni(OH)2/NF 1 M 298 -- -- [S12]
Cu-P/Cu foamb 1 M 98 55 15 [S13]
If not mentioned specifically, all overpotentials were acquired without iR compensation.
a Overpotential (η) at a current density of 10 mA/cm2; b Overpotential (η) acquired at a current density of 10 mA/cm2 with additional iR compensation.
Figure S 3-4. Comparison of the as prepared NiFe LDH@NiCoP/NF with RuO2/NF for the OER activity.
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 0
50 100 150 200 250 300 350
NiFe LDH@NiCoP/NF RuO2/NF
Current density(mA/cm2 )
V (vs. RHE)
Table S 3-4. Comparison of OER performance for NiFe LDH@NiCoP/NF with other reported electrocatalysts in the alkaline media.
Catalyst Electrolyte
(KOH）
η10a
(mV)
Tafel slope
(mV/dec) Stability (h) Ref.
NiFe LDH@NiCoP/NF 1 M 220 48.6 100 This work
NiFe/NiCo2O4/NFb 1 M 340c 45.5 10 [S1]
NiFe-LDH/NiCo2O4/NF 1 M 290 53 10 [S2]
NiFe LDH@NiCo2S4/NF 1 M 201d 46.3 10 [S3]
MoS2/Ni3S2/NFb 1 M 218 88 10 [S4]
NiO@Ni@Carbon fiber 1 M 300 60 24 [S5]
NiFe LDHs@FeOOH/NFb 1 M 208 42 20 [S14]
NiFe LDH@Co0.85Se/NFb 1 M 270e 57 10 [S6]
Ni5P4/Ni foil 1 M 290 40 20 [S9]
Ni(OH)2/NF 1 M 330d 150 24 [S10]
NiFe LDH/NF 1 M 240 58.9 -- [S8]
Ni3S2/NF 1 M 280f -- 200 [S11]
Ni(OH)2/NF 1 M 350 -- -- [S12]
Cu-P/Cu foamb 1 M 325 120 15 [S13]
RuO2b 1 M 350 85 -- [S15]
IrO2b 1 M 350 67 -- [S15]
If not mentioned specifically, all overpotentials were acquired without iR compensation.
a Overpotential (η) at the current density of 10 mA/cm2; b the overpotential was corrected with iR compensation. c Current density at 1200 mA/cm2 with 65 % iR compensation. d Current density at 50 mA/cm2. e Current density at 150 mA/cm2; f Current density at 200 mA/cm2.
Figure S 3-5. (a) XRD pattern comparison of the NiFe LDH@NiCoP, post HER and post OER measurements.
SEM images of the NiFe LDH@NiCoP heterostructure after (b) HER and (c) OER measurement, inset images are the corresponding high-resolution SEM images.
Figure S 3-6. EDX mapping of the NiFe LDH@NiCoP/NF after long time OER measurement. (a) TEM image of the NiFe LDH@NiCoP and the corresponding element distribution of (b) O, (c) Co, (d) Fe, (e) Ni and (f) P.
Table S 3-5. Comparison of the overall water splitting performance of NiFe LDH@NiCoP/NF with other reported electrocatalysts in alkaline medium.
Catalyst Electrolyte（KOH） η10a (mV) Stability (h) Ref.
NiFe LDH@NiCoP/NF 1 M 340 100 This work
NiFe/NiCo2O4/NF 1 M 440 10 [S1]
NiFe LDH/NiCo2O4/NF 1 M 370 12 [S2]
NiFe LDH@NiCo2S4/NF 1 M 370 12 [S3]
MoS2-Ni3S2/NF 1 M 330 12 [S4]
NiO@Ni@Carbon fiber 1 M 500b 60 [S5]
NiFe LDH@Co0.85Se/NF 1 M 440 10 [S6]
NiFe LDH/NF 1 M 470 3 [S8]
Ni5P4/NF 1 M 470 20 [S9]
NiCoP/NF 1 M 350 25 [S16]
NiSe/NF 1 M 400 20 [S17]
Ni3Se2/NF 1 M 380 140 [S18]
NiS/NF 1 M 410 35 [S19]
NiCo2S4/carbon cloth 1 M 450 10 [S20]
V/NF 1 M 510 24 [S21]
NiP/NF 1 M 380 4.2 [S22]
Ni(OH)2/NF 1 M 450 24 [S10]
Ni3S2/NF 1 M 530 200 [S11]
Ni(OH)2/NF 1 M 600 -- [S12]
Ni-P/Cu foam 1 M 450 15 [S13]
NiMo HNRs/Ti mesh 1 M 410 10 [S23]
CoSe/Ti mesh 1 M 430 25 [S24]
NiCo2S4/Carbon cloth 1 M 450 10 [S20]
Cu3P/NF 1 M 440 12 [S25]
a Overpotential (η) at an applied current density of 10 mA/cm2; b Current density at an applied current density of 20 mA/cm2.
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4 Optimization of Chemical Vapor Deposition Process for Carbon Nanotubes Growth on Stainless Steel: Towards Efficient Hydrogen Evolution Reaction
This chapter can be referred to:
H. Zhang; J. M. de Souza e Silva; C. S. de Oliveira; X. Lu, S. L. Schweizer, A. W. Maijenburg, M. Bron, R. B. Wehrspohn, Optimization of Chemical Vapor Deposition Process for Carbon Nanotubes Growth on Stainless Steel: Towards Efficient Hydrogen Evolution Reaction. MRS Advances 2020.