Comparative performance evaluation of self-basifying direct formate fuel cells

Formate that is capable of synthesizing from electrochemical conversion of CO₂ efficiently is emerging as one of promising fuels for direct liquid fuel cells. In this work, a comparative study on performance of self-basifying direct formate fuel cell that contains non-platinum catalysts, neutral polymer and anion-exchange membrane is reported. Experimental result shows that the peak power density (PPD) of self-basifying direct formate fuel cell reaches 47 mW cm^-2 at 60°C without additional base. It is found that the competition between the quickened electrokinetics and increased mass and charge transport resistances induces an optimal anode and cathode Pd loading of 3.0 mg cm^-2. The PPD first improves and then decreases with PTFE content in cathode, resulting in an optimal content of 10 wt%. In contrast, it decreases monotonically with anode PTFE content. In addition, the cell performance varies slightly with formate concentration due to the competitive adsorption between HCOO- and OH-. A moderate oxygen flow rate of 100 sccm is required for the highest performance. Moreover, elevating operating temperature quickens electrokinetics and facilitates mass and charge transfer, improving cell performance significantly.