Effect of loading potential variation on direct methanol fuel cell anode performance

By scanning electrochemical microscopy ( SECM ) and traditional electrochemical method, the effect of loading potential variation on direct methanol fuel cell ( DMFC ) anode performance was studied. When the anode was loaded for 2 h at different potential, the number of peak current reduced with loading potential increasing while the corresponding peak current value increased first and then decreased, which manifested that the anodes catalytic distributed rather differently and reduced with loaded time and potential. The forward and the reverse sweep current peaks in cyclic voltammetry also first moved to negative and then shifted to positive with loaded time increasing while its resistance ability to CO continuously decreased. After loaded for 16 h and 72 h at 0.6 V, the average size of catalysts changed from 3.4 nm to 3.6 nm and 4.4 nm, respectively. While loaded for 72 h at 0.8 V, the weight ratio of Pt/Ru in catalyst changed from 2.0 to 3.9. Changing loaded potential exacerbated the uneven distribution of catalytic site, catalyst particle enlargement and Ru lose, which contributed to the catalytic activity deterioration.