Electrooxidation of Methanol at PANI/POAP Bilayered Structure Modified Platinum and Graphite Electrodes

• Electrodeposition of Polyaniline/Poly(o-aminophenol) bilayered structure on platinum and graphite substrates for methanol oxidation.
• PANI/POAP-Gra electrode showed less reactivity and stability towards methanol oxidation.
• PANI/POAP-Pt electrode exhibited superior performance with high methanol oxidation current, capacitance and specific capacitance.
• The dielectric properties and AC conductivity of the PANI/POAP-Pt electrode with respect to the applied potential were evaluated.

Polyaniline/Poly(o-aminophenol) (PANI/POAP) bilayered films were deposited by electro polymerization on platinum (Pt) and graphite (Gra) electrodes for methanol oxidation in direct methanol fuel cells. The chemical composition of bilayered structure was characterized by Fourier transform infrared (FTIR) spectroscopy. Results demonstrated the presence of FTIR peaks associated to PANI and POAP constituents confirming the bonding of PANI and POAP in the bilayered composite structure. The electrochemical properties of PANI/POAP electrodes were examined in pure and sulfuric acid mixed methanol solutions using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). PANI/POAP-Gra electrode showed less reactivity towards methanol oxidation, as well as poor stability upon repeated cycling. On the other hand, PANI/POAP-Pt electrode exhibited superior performance with high methanol oxidation current (Ia), capacitance (C), and specific capacitance (Cs). In addition, PANI-POAP-Pt electrode was found better than PANI-POAP-Gra electrode in terms of operation stability based on continuous cycling in methanol up to 100 cycles. The dielectric properties and AC conductivity (σac) of the PANI/POAP-Pt electrode with respect to the applied potential have been discussed.