Study Of The Electrocatalysis Of Polyaniline-Modified Platinum For The Oxidation Of Sodium Formate System

Polyaniline(PANI),a typical conductive polymer,has been widely studied because of its diverse structures,high conductivity,unique doping mechanism,excellent physical properties,good environmental stability,cheap raw materials and simple synthesis method.In this dissertation,a chemical method,with p-toluenesulfonic acid(p-TSA)as an H+-doping agent and ammonium persulfate as an oxidizing agent,was applied to polymerize aniline monomers and prepare doped PANI.SEM,XRD,FT-IR and EDS methods were used to characterize the PANI;standard four-probe method was used to test the conductivity of PANI;cyclic voltammetry(CV)method was used to study the electrochemical activity of polyaniline-modified platinum(PANI/Pt)electrode in 0.1 mol/L sulfuric acid solution.Experiment results show that aniline is able to polymerize to a cluster-like PANI on the surface of Pt electrode.Moreover,the modified electrode PANI/Pt has good electrochemical activity.Cyclic voltammetry method was applied to study the electrocatalytic performance of PANI/Pt electrode on formic acid-formate oxidation in the mixed aqueous solution with different concentrations HCOONa and 0.1 mol/L H2SO4.The results show that PANI/Pt can catalyze the oxidation of formic acid-formate more efficiently.The initial potential of the oxidation is lower than-0.2 V,which is closed to the initial oxidation potential of formic acid when palladium is used as the catalyst.Under the condition of 2.0 mol/L sodium formate and 0.1 mol/L sulfuric acid,the potential of oxidation peak is 0.38 V and the maximum current density of oxidation peak is 0.014 A/cm2.Based on the widely accepted dual-path mechanism,the third pathway of formic acid electrooxidation is proved to be in existence according to our results.Further experimental results indicate that formic acid-formate electrooxidation via the third pathway is significant in a wide formate concentration range.And at the same time,the indirect pathway in the duel-path mechanism is inhibited strongly.When the ChCOONa =2.0 mol/L,the electric catalysis of PANI/Pt to the oxidation-via the third path is the best.Under this experimental condition,when the CHCOONa is among 0.8-2.5 mol/L in 0.1 mol/L sulfuric acid solution,the ratio of integral quantity by the direct route to by the total quantity is greater than or equal to 60%.Homemade sodium formate fuel cells.Analysis the catalytic oxidation output voltage at different concentration of sodium formate-0.1 mol/L sulfuric acid.The results show that when the concentration of sodium formate from 1.5 to 2.0 mol/L,the average output voltage can reach 0.48 V high and stable rapidly.And then we analyze the methods of solving the battery efficiency in theory.