Supplementary Information
Facet-Dependent Electrochemical Properties of Co3O4 Nanocrystals toward
Heavy Metal Ions
Xin-Yao Yu,1 Qiang-Qiang Meng,2 Tao Luo,1 Yong Jia,1 Bai Sun,1 Qun-Xiang Li,2,*
Jin-Huai Liu,1 and Xing-Jiu Huang1,*
1Research
Center for Biomimetic Functional Materials and Sensing Devices, Institute of Intelligent Machines, Chinese
Academy of Sciences, Hefei 230031, PR China. 2Hefei National Laboratory for Physical Science at the Microscale,
University of Science and Technology of China, Hefei, Anhui 230026, PR China. *Correspondence should be addressed to
X.J.H (E-mail: xingjiuhuang@iim.ac.cn) and Q.X.L (E-mail: liqun@ustc.edu.cn).
Figure S1. Scheme of the route for preparation of Co3O4 nanocubes and nanoplates.
Figure S2. a, low magnification SEM and b, TEM images of Co3O4 nanoplates.
-1-
Figure S3. XRD pattern of Co3O4 nanoplates precursor (black line), Co3O4 nanoplates (red
line) and Co3O4 nanocubes (blue line).
Figure S4. BET nitrogen adsorption isotherms of Co3O4 nanoplates and nanocubes.
Figure S5. a, Cyclic voltammograms and b, Nyquist diagrams of electrochemical impedance
spectra of bare GCE, Co3O4 nanocubes and Co3O4 nanoplates modified GCE in the solution
of 5 mM Fe(CN)63-/4- and 0.1 M KCl, respectively.
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Figure S6. SWASV responses of 1.0 μM Pb(II) on bare, Co3O4 nanocubes and Co3O4
nanoplates modified GCE in 0.1 M NaAc-HAc (pH= 5.0). Deposition potential: -1.2 V,
accumulation time: 180 s, step potential 5 mV, amplitude 20 mV, frequency 25 Hz.
Figure S7. SWASV responses of a, Co3O4 nanoplates and b, Co3O4 nanocubes modified
electrode toward Pb(II) at different concentrations in 0.1 M NaAc-HAc solution (pH= 5.0).
The concentration range for nanoplates and nanocubes modified electrode is 0.3-1.4 μM and
0.7-1.7μM, respectively.
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Figure S8. Linearized Langmuir isotherms of Pb(II) onto a, Co3O4 nanoplates and b, Co3O4
nanocubes.
Figure S9. The slab model of Co3O4(001) surface: a, Side view, b, Top view of 1×1 supercell;
c, Side view, d, Top view of
2´
2 supercell. In a
2´
2 supercell, there are 4 stable
adsorption sites for Pb atoms on Co3O4(001) surface labeled with I within cyan circles in
panel d.
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Figure S10. The slab model of Co3O4 (111) surface: a, Side view, b, c Top view. In a unit
cell, there are 4 stable adsorption sites labeled by II within cyan circles in panel b, and 12
second stable adsorption sites labeled by II′ within cyan circles in panel c for Pb/Co3O4(111)
system.
Figure S11. The Bader charge analysis for Pb atom on Co3O4 surfaces: a, Pb/Co3O4(001)
surface and b, Pb/Co3O4(111) surface. The blue and red colors stand for the losing and
gaining electron, respectively.
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Figure S12. The diffusion paths of Pb on Co3O4 surfaces: a, Pb/Co3O4(001) surface with two
diffusion directions. b, Pb/Co3O4(111) surface with six directions. Here, the directions are
labeled with black solid lines with arrow for clarity.
Table S1. The adsorption energies (in eV) of low- and high-coverage of Pb on Co3O4 (001)
and (111) surfaces using different computational schemes.
Pb/Co3O4
(001)
(111)
PBE
-3.70
-4.11
low-coverage of Pb
PBE+U
relativistic corrections
-5.65
-3.98
-5.88
-4.30
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high-coverage of Pb
PBE
-3.38
-3.69