Improved DMFC water management via superwetting, high-performance catalyst synthesized by nanocapsule method

In this paper, an effective water management structure for direct methanol fuel cell (DMFC) is designed based on the super-hydrophilicity of nitrogen-doped carbon aerogel which functions as the support of Pt catalyst. Considering the case where Pt nanoparticles deposited into the nanopores of the support are difficult to contact with the ionomer, the catalyst is synthesized by nanocapsule method, and the experimental results prove that a favorable improved oxygen reduction reaction activity of the prepared catalyst has been achieved. The produced hydrophilic catalyst is used to construct a two-layered cathode catalyst layer (CCL) with hydrophilic inner layer and hydrophobic outer layer as water management structure, since a single-layered hydrophilic CCL shows poor performance due to serious water flooding. A mathematical model is developed to study the influence of two-layered CCL, and its effect on cell performance is also analyzed by polarization tests. For the improved liquid-feed DMFCs, high hydraulic pressure is formed in CCL to promote water recovery and inhibit methanol cross-over. For the improved vapor-feed DMFC, the enhanced water recovery secures the water required for the anodic oxidation reaction, which increases the output performance and stability greatly. This study provides a new method for the optimization of DMFC.