Electrochemical impedance analysis of methanol oxidation on carbon nanotube-supported Pt and Pt-Ru nanoparticles


Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are employed to investigate methanol oxidation reactions on single-walled carbon nanotube-supported platinum (Pt) and platinum-ruthenium (Pt-Ru) nanoparticles. EIS and CV measurements show consistent results: Pt catalyst supported on single-walled carbon nanotubes possesses higher catalytic activity for methanol oxidation than that on carbon black. Additionally, semicircles in the second quadrant of the Nyquist diagrams are observed for methanol oxidation on all types of catalytic nanoparticles when applying an electrical potential of 600 mV, which indicates the occurrence of negative resistance during electrocatalytic methanol oxidations. However, all impedance spectra show positive resistance at other electrode potentials (e.g., 300, 400, and 800 mV). Electrocatalytic characteristics of all catalysts are further analyzed by equivalent circuit simulations. We propose that intermediate coverage on the catalyst surface and subsequently the oscillation of nonlinear electrochemical methanol oxidations lead to the occurrence of negative resistance at 600 mV.


Physics, Astronomy, and Materials Science

Document Type





direct methanol fuel cell, anode catalyst, methanol oxidation, electrochemical impedance spectroscopy, negative resistance, equivalent circuit

Publication Date


Journal Title

Journal of Solid State Electrochemistry