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A comparative study of four common-used anode gas diffusion layers [A-GDLs,namely carbon paper,carbon cloth,carbon paper based Toray-GDL and homemade carbon nanotubes based gas diffusion layer(CNT-GDL)] for direct methanol fuel cells(DMFCs)was carried out and discussed.The results of scanning electron microscope(SEM),mercury intrusion porosimeter(MIP)and gas/water permeability showed that CNT-GDL is of larger porosity in pore size of 1000-3000 nm and largest total porosity,compared with those of the other three.Carbon paper and Toray-GDL showed disadvantageous influences on cell performances at high current density,due to carbon paper with many large pores were unsuited for water diffusion,while Toray-GDL with many small pores were unsuited for gas diffusion.Though carbon cloth showed the highest methanol transfer coefficient,the cell with carbon cloth showed a little lower performance than that of CNT-GDL due to its thickness.Anode polarization results displayed that the cell with CNT-GDL had the least methanol mass transfer resistance for its proper porosity during the four cells with different A-GDLs.As a result,the cell with CNT-GDL showed the highest limiting current density and peak power density of 460 mA cm-2 and 110 mW cm-2,respectively.