A look at the enhancements in battery operation by utilizing reduced graphene oxide as an electrode substrate. Visit our website, KamatLab.com, for the latest news, publications, and research from our group.

1. ACS Catal., 2012, 2, pp 807–816
DOI: 10.1021/cs3001286 1

2. Motivation
Reduced graphene oxide is composited with many intercalation compounds in
many recent studies, with significant improvement in performance. But…Why?
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3. Approach
•Prepare Reduced Graphene Oxide (RGO)/ -MnO2 Nanowire Composite
•Synthesize different lengths of nanowires to differentiate effects inherent to MnO2
from those afforded by RGO
•Characterize composites using electron microscopy and x-ray diffraction
•Evaluate the electrochemical response of the composite electrode using
chronocoulometry and impedance spectroscopy
•Determine the overall cycling characteristics of the optimized electrode
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4. Morphology
•Short nanowires (SNW) exhibit higher crystallinity
•RGO enhances crystallinity during synthesis
•Mixed morphology (alpha/ramsdellite MnO2)
•Mn2O3 and Mn3O4 impurities
Synthesis adapted from: Chen, S., et. al, ACS Nano, 2010, 4(5), 2822-2830 4

5. RGO in 3-D
•Wrinkling characteristic of RGO generates 3-D macrostructure
•Intimate contact between nanowires and RGO
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6. RGO Self-Repair of Impurities
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7. Charge-Discharge Cycling
a – rLNW
b – LNW Controls:
c – rSNW LNW + 30% C
d – SNW r + LNW
e – LNW + 30% C
f – r + LNW 7

8. EIS and Chronocoulometry
Electron Storage on RGO: Lightcap, I. V., Kosel, T. H., Kamat, P. V., Nano Lett., 2010, 4, 577–583
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9. Summary
•Utilized -MnO2 nanowires of different lengths to probe the role of
RGO in electrochemical energy storage electrodes
•RGO serves to increase crystallinity in the final active material and
catalyzes self-repair of partially-oxidized manganese oxide impurities
•RGO significantly reduces the charge-transfer impedance at the
electrode-electrolyte interface
•RGO acts as kinetic mediator between electrons and lithium ions via its
surface storage of electrons and enhanced diffusion of Li+ through its 3-D
macrostructure
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10. Thank You!
This work can be found in ACS Catalysis
ACS Catalysis 2, 807-816 2012
DOI: 10.1021/cs3001286
More information on the Kamat Research Group can be found at:
www.kamatlab.com
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