Supplementary information for

Inductive Effect between Atomically Dispersed Iridium and

Transition-Metal Hydroxide Nanosheets Enables Highly Efficient

Oxygen Evolution Reaction

Yulin Xinga, Jiangang Kub, Weng Fuc, Lianzhou Wangc*, Huihuang Chena*

aHefei National Laboratory for Physical Sciences at the Microscale, University of Science and

Technology of China, Hefei 230026, China.

bSchool of Zijin Mining, Fuzhou University, Fuzhou 350108, China.

cSchool of Chemical Engineering, The University of Queensland, Brisbane Qld 4072, Australia.

* Correspondent authors:

Tel: + 86 183 5514 9603, Fax: +86-551-63606266, Email: hhchen@ustc.edu.cn (Huihuang Chen)

Email: l.wang@uq.edu.au (Lianzhou Wang)

Figure S1. HADDF-STEM image of 6% Ir-Ni(OH)2. Further doping over 4% resulted in large-sized

Ir particles.

Figure S2. Overpotentials required for each sample at the current density of 10 mA cm-2. 4% Ir-

Ni(OH)2 required the lowest overpotential to reach 10 mA cm-2.

2 nm

Figure S3. (a) TEM image, (b) HADDF-STEM image, and XRD pattern of spent 4% Ir-Ni(OH)2

after the stability test. Spent 4% Ir-Ni(OH)2 retained the nanosheet morphology/structure and

maintained the uniform distribution of atomic Ir species.

Figure S4. The experimentally measured and theoretically calculated amount of molecular oxygen

versus time for 4% Ir-Ni(OH)2 at the current density of 10 mA cm-2. The experimentally quantified

rate of O2 evolution matches well with the theoretically calculated value.

2 nm100 nm

a b c

Figure S5. Overall water splitting tests of 4% Ir-Ni(OH)2. (a) Schematic diagram of the overall water

splitting device. (b) The polarization curves of 4% Ir-Ni(OH)2||Pt@C for overall water splitting in the

two-electrode cell in 1.0 M KOH electrolyte. The commercial IrO2||Pt@C coupled electrolyzer was

used as a reference. (c) Chronopotentiometric curve of 4% Ir-Ni(OH)2||Pt@C for overall water

splitting at 10 mA cm−2 for 20 h.

Figure S6. Brunauer-Emmett-Teller (BET) surface area/electrochemical surface area (ECSA)

normalized current densities at η=300 mv. 4% Ir-Ni(OH)2 demonstrated higher intrinsic catalytic

activity toward OER compared to Ni(OH)2.

b ca

Figure S7. Double layer capacitance (Cdl) measurements in 1.0 M KOH electrolyte. CVs measured

in the non-Faradaic region of -0.10 to 0.0 V vs AgCl for Ni(OH)2 (a) and 4% Ir-Ni(OH)2 (c). Cdl

calculated by using varying scan rates from 20 to 100 mV s-1 for Ni(OH)2 (b) and 4% Ir-Ni(OH)2 (d).

Figure S8. The illustration of inductive effect between Ir sites and Ni sites.

a b

c d

Ni(OH)2 Ni(OH)2

4% Ir-Ni(OH)2 4% Ir-Ni(OH)2

Figure S9. The polarization curves of 4% Ir-Fe(OH)3 and Fe(OH)3 for OER in 1.0 M KOH. The

current density of 4% Ir-Fe(OH)3 and Fe(OH)3 did not reach 10 mA cm-2 in the applied potential

range.

Figure S10. FTIR spectra of Ni(OH)2 and 4% Ir-Ni(OH)2. Ir doping into Ni(OH)2 enhanced the

adsorption of oxygen containing species on the catalyst surface.

Figure S11. Nyquist plots (inset: enlarged semicircle diameter) of 4% Ir-Ni(OH)2 and Ni(OH)2.

Figure S12. XRD patterns of 4% Ir-α-Co(OH)2, 4% Ir-β-Co(OH)2, 4% Ir-CoMn LDH, and the

corresponding undoped counterparts.

Figure S13. TEM images of α-Co(OH)2 (a), 4% Ir-α-Co(OH)2 (b), β-Co(OH)2 (c), 4% Ir-β-Co(OH)2

(d), Ir-CoMn LDH (e), and 4% Ir-CoMn LDH (f).

200 nm 200 nm

200 nm 200 nm

200 nm 200 nm

a b

c

e

d

f

Table S1. Comparison of OER performance of IrO2 reported in the literature.

Catalyst Electrolyte Overpotential (mV)

@ 10 mA cm-2 Reference

IrO2 1.0 M KOH 394 [1]

IrO2 1.0 M KOH 320 [2]

IrO2 1.0 M KOH 406 [3]

IrO2 1.0 M KOH 352 [4]

IrO2 1.0 M KOH 322 [5]

IrO2 1.0 M KOH 335 [6]

IrO2 1.0 M KOH 330 [7]

IrO2 1.0 M KOH 440 [8]

IrO2 1.0 M KOH 427 [9]

IrO2 1.0 M KOH 332 This work

Table S2. Comparison of OER performance of recent publications in 1.0 M KOH aqueous solution.

Catalysts Overpotential (mV)

@ 10 mA cm-2 Tafel slope (mV dec-1) Ref.

4% Ir-Ni(OH)2 235 58.4 This work

CoFePx 323 58 [10]

Co-PDY 270 99 [11]

CoFe2O4 NSs 275 42.1 [12]

NiO/CN 261 58.9 [13]

MoOx@N-doped MoS2−x 270 61 [14]

Tannin-NiFe/CP 290 28 [15]

Co1−xVxOOH 190 39.6 [16]

NiFe@g-C3N4/CNTs 326 67 [17]

Ni(OH)2/NiOOH 256 41 [18]

Ni0.67Fe0.33/C 210 35.1 [19]

Ni0.8Fe0.2 NSs 206 64 [20]

HHTP@ZIF-67 238 104 [21]

NiFe-LDH 280 49.4 [22]

NixB 380 89 [23]

SnCo0.9Fe0.1(OH)6-Ar 300 42.3 [24]

CoFe LDHs-Ar 266 37.9 [25]

CoO 330 44 [26]

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