Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

Journal Article · Thu Oct 15 00:00:00 EDT 2015 · AIP Advances

DOI:https://doi.org/10.1063/1.4933190· OSTI ID:22492126

Gupta, Sanju; Price, Carson ^[1]

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1. Department of Physics and Astronomy, Western Kentucky University, 1906 College Heights Blvd., Bowling Green, KY 42101-3576 (United States)

Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO){sub 1}, (PPy/ErGO){sub 1}, (PAni/GO){sub 1} and (PPy/GO){sub 1}. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, C{sub s}, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent C{sub s} of ≥350 F g{sup −1} as compared with constituents (∼70 F g{sup −1}) at discharge current density of 0.3 A g{sup −1} that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (re)activity of surface ion adsorption sites density at solid/liquid interface.

• OSTI ID: 22492126
• Journal Information: AIP Advances, Vol. 5, Issue 10; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 2158-3226
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
CAPACITANCE
CAPACITIVE ENERGY STORAGE EQUIPMENT
CAPACITORS
CURRENT DENSITY
DIFFUSION
ELECTROCHEMISTRY
ELECTROLYTES
GRAPHENE
INTERFACES
IONS
LAYERS
LIQUIDS
MICROSCOPY
NANOSTRUCTURES
OXIDES
POLYMERIZATION
POLYMERS
REDUCTION
THIN FILMS