| Direct formic acid fuel cell have been receiving great attention around the world due to its high energy density, the safety of using, the high open circuit potential. Currently, the mechanism of electro-catalytic oxidation of formic acid,which is used to be the fuel for fuel cell been studied extensively,while the research and development of the catalyst material,the electrode structure and the battery system for the fuel cell were going on. At present, the electro-oxidation of formic acid can be carried out by the dual path mechanism:One is an indirect way, also called CO way, which is the reaction of formic acid from CO, and then the CO oxidizes to CO2. The other one is a direct way, that is formic acid loses two H+, then oxidizes to CO2 directly.. Although a lot of electrochemical research methods and in-situ spectroscopy methods have been used to study the electro-catalytic oxidation of formic acid, but the contribution and the role of both methods in the process of the reaction is still unknown, and the intermediate of formic acid is controversial.This thesis applied the new diagnostic methods of nonlinear electrochemical spectroscopy--total harmonic distortion (THD) to investigate the nonlinear frequency response behaviour of electro-catalytic oxidation of formic acid in on platinum and gold electrode. By changing pH and the concentration of formic acid, examining the influence of the concentration of formic acid, the PH of the reaction system on the steady-state polarization of formic acid oxidation, linear frequency response (ie:AC impedance spectroscopy) and the non-linear frequency response. And the process of formic acid oxidation were simulated. The experimental results showed that:at low potential, formic acid is more reactive, and at high potential, formate is more reactive, the electrooxidation of formic acid is controlled by both formic acid and formate at different pH, and the THD technology has it's advantage applying to the concentration sensor of formic acid. |
PDF Full Text Request