Real contribution of formic acid in direct formic acid fuel cell: Investigation of origin and guiding for micro structure design

We first experimentally verified the real contribution of formic acid (FA) in the direct formic acid fuel cell (DFAFC). By comparing the cell performance of the fuel cell fueled with FA and methanol, we found that FA not only acts as fuel in the fuel cell, but is also of benefit to proton conducting and triple phase boundary (TPB) building in the anode. Considering the real contribution and the special mass transfer behavior of FA in the fuel cell, the anode was reasonably designed and optimized. Carbon cloth was selected as the optimized anode diffusion layer to achieve quick methanol transfer from fuel reservoir to anode catalyst. The decal method was proved to be the better choice for membrane electrode assembly (MEA) fabrication than the traditional hot pressing because it can result in better TPB building and lowering the FA crossover. DFAFC performed approximately 60% better after these anodic micro structure optimizations.

► Real contribution of formic acid (FA) in DFAFC was studied. ► FA was proved to be of great benefit to the proton conduction and TPB building. ► The anode of DFAFC was optimized with the guiding of FA's real contribution. ► Construction and fabrication method of MEA were adjusted. ► The passive DFAFC performed 60% better after structural optimizing.