Nitrogen-Doped Graphene Supported CoSe2 Nanobelt Composite ...
Supporting Information for
Nitrogen-Doped Graphene Supported CoSe2 Nanobelt Composite Catalyst for Efficient Water Oxidation Min-Rui Gao, Xuan Cao, Qiang Gao, Yun-Fei Xu, Ya-Rong Zheng, Jun Jiang, Shu-Hong Yu*
Homepage: http://staff.ustc.edu.cn/~yulab Subpage: http://minrgao.weebly.com
Figure S1. (a, b) Additional TEM images of the NG-CoSe2 composite prepared at 180 oC for 12 h with a volume ratio of VDETA/VGO-DIW-suspension = 2:1.
S1
Figure S2. TEM image of the as-prepared large GO sheets.
Figure S3. TEM images of the products prepared at 180 oC for 12 h with different volume ratio of VDETA/VGO-DIW-suspension. (a) 5:1; (b) 3:1; (c) 2:5; (d) 1:6.
S2
110
Relative Mass / %
100
21.2 wt% weight loss from NG
90 80 70 60 50 40 30 20 10 0
100 200 300 400 500 600 700 800 900
Temperature / oC Figure S4. TGA curve of the NG-CoSe2 composite. The measurement was performed under nitrogen with a heating rate of 10 oC min-1.
S3
Figure S5. SAED patterns of NG (a) and NG-CoSe2 composite (b), respectively.
S4
Figure S6. Additional HRTEM images of the NG-CoSe2 composite catalyst.
S5
Figure S7. CV curves for modified GC electrodes comprising the NG-CoSe2 composite (a), pure CoSe2 nanobelts (b), commercial RuO2 (c), and 20 wt% Pt/C (d) with (red) and without (blue) correction for iR losses. The ionic resistance (~45 Ω) from the solution was determined by the EIS technique.
S6
Figure S8. SEM image of the physical mixture of NG sheets and CoSe2 NBs. The mass ratio of NG sheets and CoSe2 NBs (21.2/78.8 w/w) is the same as that of chemically synthesized NG-CoSe2 composite to ensure the fair comparison.
S7
25
j / mA cm-2
20
NG-CoSe2 composite NG & CoSe2 NBs
15 10 5 0 1.2
1.4
1.6
1.8
E / V vs. RHE, iR-corrected Figure S9. Polarization curves for OER on NG-CoSe2 composite and the physical mixture of NG sheets and CoSe2 NBs, demonstrating clearly that the NG-CoSe2 composite effects more efficient OER catalysis. Catalyst loading: 0.2 mg cm-2.
S8
Table S1. Summary of literature Tafel slopes of various cobalt-based OER catalysts Catalyst
Electrolyte
Tafel Slope [mV/decade]
Reference
CoOx film
1 M KOH
42
S1
Co3O4/N-rmGO
1 M KOH
67
S2
CdO/Co3O4
1 M KOH
61~65
S3
NixCo3-xO4 nanowire arrays
1 M KOH
59~64
S4
CoPi (Pi = phosphate)
0.1 M KPi
60
S5
CoOx (amorphous)
0.1 M KOH
42±2
S6
FeCoOx (amorphous) Mn3O4/CoSe2
0.1 M KOH
33±5
S6
0.1 M KOH
64
S7
NG-CoSe2
0.1 M KOH
40
Present work
Supplementary references S1.
S2.
S3.
S4. S5.
S6.
S7.
Trotochaud, L.; Ranney, J. K.; Williams, K. N.; Boettcher, S. W. Solution-Cast Metal Oxide Thin Film Electrocatalysts for Oxygen Evolution. J. Am. Chem. Soc. 2012, 134, 17253-17261. Liang, Y. Y.; Li, Y. G.; Wang, H. L.; Zhou, J. G.; Wang, J.; Regier, T.; Dai, H. J. Co3O4 Nanocrystals on Graphene as A Synergistic Catalyst for Oxygen Reduction Reaction. Nat. Mater. 2011, 10, 780-786. Nkeng, P.; Koenig, J. F.; Gautier, J. L.; Chartier, P.; Poillerat, G. Enhancement of Surface Areas of Co3O4 and NiCo2O4 Electrocatalysts Prepared by Spray Pyrolysis. J. Electroanal. Chem. 1996, 402, 81-89. Li, Y. G.; Hasin, P.; Wu, Y. Y. NixCo3-xO4 Nanowire Arrays for Electrocatalytic Oxygen Evolution. Adv. Mater. 2010, 22, 1926-1929. Surendranath, Y.; Kanan, M. W.; Nocera, D. G. Mechanistic Studies of the Oxygen Evolution Reaction by a Cobalt-Phosphate Catalyst at Neutral pH. J. Am. Chem.Soc. 2010, 132, 16501-16509. Smith, R. D. L.; Prévot, M. S.; Fagan, R. D.; Zhang, Z. P.; Sedach, P. A.; Siu, M. K. J.; Trudel, S.; Berlinguette, C. P. Photochemical Route for Accessing Amorphous Metal Oxide Materials for Water Oxidation Catalysis. Science 2013, 340, 60-63. Gao, M. R.; Xu, Y. F.; Jiang, J.; Zheng, Y. R.; Yu, S. H. Water Oxidation Electrocatalyzed by an Efficient Mn3O4/CoSe2 Nanocomposite. J. Am. Chem. Soc. 2012, 134, 2930-2933.
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Nitrogen-Doped Graphene Supported CoSe2 Nanobelt Composite Catalyst for Efficient Water Oxidation Min-Rui Gao, Xuan Cao, Qiang Gao, Yun-Fei Xu, Ya-Rong Zheng, Jun Jiang, Shu-Hong Yu*
Homepage: http://staff.ustc.edu.cn/~yulab Subpage: http://minrgao.weebly.com
Figure S1. (a, b) Additional TEM images of the NG-CoSe2 composite prepared at 180 oC for 12 h with a volume ratio of VDETA/VGO-DIW-suspension = 2:1.
S1
Figure S2. TEM image of the as-prepared large GO sheets.
Figure S3. TEM images of the products prepared at 180 oC for 12 h with different volume ratio of VDETA/VGO-DIW-suspension. (a) 5:1; (b) 3:1; (c) 2:5; (d) 1:6.
S2
110
Relative Mass / %
100
21.2 wt% weight loss from NG
90 80 70 60 50 40 30 20 10 0
100 200 300 400 500 600 700 800 900
Temperature / oC Figure S4. TGA curve of the NG-CoSe2 composite. The measurement was performed under nitrogen with a heating rate of 10 oC min-1.
S3
Figure S5. SAED patterns of NG (a) and NG-CoSe2 composite (b), respectively.
S4
Figure S6. Additional HRTEM images of the NG-CoSe2 composite catalyst.
S5
Figure S7. CV curves for modified GC electrodes comprising the NG-CoSe2 composite (a), pure CoSe2 nanobelts (b), commercial RuO2 (c), and 20 wt% Pt/C (d) with (red) and without (blue) correction for iR losses. The ionic resistance (~45 Ω) from the solution was determined by the EIS technique.
S6
Figure S8. SEM image of the physical mixture of NG sheets and CoSe2 NBs. The mass ratio of NG sheets and CoSe2 NBs (21.2/78.8 w/w) is the same as that of chemically synthesized NG-CoSe2 composite to ensure the fair comparison.
S7
25
j / mA cm-2
20
NG-CoSe2 composite NG & CoSe2 NBs
15 10 5 0 1.2
1.4
1.6
1.8
E / V vs. RHE, iR-corrected Figure S9. Polarization curves for OER on NG-CoSe2 composite and the physical mixture of NG sheets and CoSe2 NBs, demonstrating clearly that the NG-CoSe2 composite effects more efficient OER catalysis. Catalyst loading: 0.2 mg cm-2.
S8
Table S1. Summary of literature Tafel slopes of various cobalt-based OER catalysts Catalyst
Electrolyte
Tafel Slope [mV/decade]
Reference
CoOx film
1 M KOH
42
S1
Co3O4/N-rmGO
1 M KOH
67
S2
CdO/Co3O4
1 M KOH
61~65
S3
NixCo3-xO4 nanowire arrays
1 M KOH
59~64
S4
CoPi (Pi = phosphate)
0.1 M KPi
60
S5
CoOx (amorphous)
0.1 M KOH
42±2
S6
FeCoOx (amorphous) Mn3O4/CoSe2
0.1 M KOH
33±5
S6
0.1 M KOH
64
S7
NG-CoSe2
0.1 M KOH
40
Present work
Supplementary references S1.
S2.
S3.
S4. S5.
S6.
S7.
Trotochaud, L.; Ranney, J. K.; Williams, K. N.; Boettcher, S. W. Solution-Cast Metal Oxide Thin Film Electrocatalysts for Oxygen Evolution. J. Am. Chem. Soc. 2012, 134, 17253-17261. Liang, Y. Y.; Li, Y. G.; Wang, H. L.; Zhou, J. G.; Wang, J.; Regier, T.; Dai, H. J. Co3O4 Nanocrystals on Graphene as A Synergistic Catalyst for Oxygen Reduction Reaction. Nat. Mater. 2011, 10, 780-786. Nkeng, P.; Koenig, J. F.; Gautier, J. L.; Chartier, P.; Poillerat, G. Enhancement of Surface Areas of Co3O4 and NiCo2O4 Electrocatalysts Prepared by Spray Pyrolysis. J. Electroanal. Chem. 1996, 402, 81-89. Li, Y. G.; Hasin, P.; Wu, Y. Y. NixCo3-xO4 Nanowire Arrays for Electrocatalytic Oxygen Evolution. Adv. Mater. 2010, 22, 1926-1929. Surendranath, Y.; Kanan, M. W.; Nocera, D. G. Mechanistic Studies of the Oxygen Evolution Reaction by a Cobalt-Phosphate Catalyst at Neutral pH. J. Am. Chem.Soc. 2010, 132, 16501-16509. Smith, R. D. L.; Prévot, M. S.; Fagan, R. D.; Zhang, Z. P.; Sedach, P. A.; Siu, M. K. J.; Trudel, S.; Berlinguette, C. P. Photochemical Route for Accessing Amorphous Metal Oxide Materials for Water Oxidation Catalysis. Science 2013, 340, 60-63. Gao, M. R.; Xu, Y. F.; Jiang, J.; Zheng, Y. R.; Yu, S. H. Water Oxidation Electrocatalyzed by an Efficient Mn3O4/CoSe2 Nanocomposite. J. Am. Chem. Soc. 2012, 134, 2930-2933.
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