Modification of proton conductive channels (PCCs) in Nafion has been achieved with the assistance of 3, 4-dimethylbenzaldehyde (DMBA). During annealing, ionic clusters develop from small isolated spheres (1.72 nm) to wide continuous channels (5.15 nm), and the crystallinity of Nafion/DMBA membranes is also improved from 17% to 32% as shown by X-ray diffraction. Molecular dynamic simulation reveals that hydrogen bonding and hydrophobic interaction between DMBA and Nafion work synergistically to achieve better phase separation. The morphology-property relationship shows that, versus various PCCs width, the corresponding proton conductivities vary greatly from 0.079 to 0.139 S/cm at 80 degrees C. By carefully tuning the width of PCCs, the proton conductivity shows an improvement of 22-34% as compared with pristine Nafion. A significant enhancement on the maximum power density is achieved for the membrane electrode assembly on Nafion/DMBA-8h (as high as 1018 mW/cm(-2)), yielding an enhancement of 39% on pristine Nafion-8h (730 mW/cm(-2)). (C) 2014 Wiley Periodicals, Inc.