Flow Rate Effect on Methanol Electro-oxidation in a Microfluidic Laminar Flow System

The effect of flow rate on the methanol electro-oxidation reaction in laminar flow was investigated using a direct methanol laminar flow fuel cell (LF-FC). A micro fuel cell was fabricated in polydimethylsiloxane using standard soft-lithography techniques. The electrochemical performance of methanol oxidation was characterized by anode polarization and electrochemical impedance spectroscopy analysis with and without sulfuric acid. The results show that in the absence of a sulfuric acid electrolyte (H2SO4) the methanol flow rate significantly influences methanol oxidation kinetics of the laminar flow direct methanol fuel cell. In the absence of H2SO4, it was found that the charge transfer resistance and onset potential of the methanol oxidation reaction significantly increases as the methanol flow rate increases. As a result, the anode current density of LF-FCs decreases at higher flow rates of methanol. However, this negative effect was reduced when a strong electrolyte, such as sulfuric acid, was mixed with the methanol solution.