Optimization of Mass Transport within Direct Formic Acid Fuel Cell Catalyst Layer via Pore Formers

Abstract

Direct formic acid fuel cells (DFAFC) offer a potentially sustainable alternative to the batteries in portable devices due to their higher charge capacity, higher efficiency, and smaller size. However, due to the two-phase flow in the anode catalyst layer and the small pore size between agglomerates in the catalyst layer (~20 nm), mass transport limitations plague the performance of the DFAFC. To maximize the performance, the two-phase transport of the reactant (formic acid, liquid) and the product (carbon dioxide, gas) must be optimized. By incorporating 15 and 25 wt% MgO, the electrochemical surface area (ECSA) of the catalyst layer increased from 21.8 cm2 g-1 to 62.7 and 85.8 cm2 g-1, respectively. Furthermore, at higher potentials the porous catalyst layers improved cell performance by 86%. These improvements in ECSA and cell performance are possibly due to an enhancement of the triple-phase boundary.