Aligned polyaniline nanorods in situ grown on gas diffusion layer and their application in polymer electrolyte membrane fuel cells

•Polyaniline nanorods are grown on gas diffusion layer by in situ polymerization.•The length of polyaniline nanorods can be changed by altering polymerization condition.•The polyaniline nanorods can increase oxygen transport of cathode catalyst layer.•The PEMFC with optimized polyaniline nanorods shows better performance.

Catalyst layers (CLs) with spatially ordered structure can improve mass transport of reactants/products, which is essential for the high performance of polymer electrolyte membrane fuel cells (PEMFCs). In this study, aligned polyaniline (PANI) nanorods grown on gas diffusion layers by in situ polymerization are used as supports for platinum to fabricate ordered CLs. The length and diameter of the PANI nanorods can be controlled by optimizing the reaction temperatures or the aniline concentrations during the in situ polymerization process. With the optimized aligned PANI nanorods as supports of cathode, the mass specific power density of the PEMFC reaches 2.5 kW gPt−1, which is 21% higher than that of the conventional PEMFC without PANI. This improvement can be attributed to the reduced oxygen transport resistance revealed by oxygen gain and electrochemical impedance spectroscopy.