Optimization of a Perovskite Oxide-Based Cathode Catalyst Layer on Performance of Direct Ammonia Fuel Cells

To maximize fuel cell performance, transport pathways for electrons, ions, and reactants should be connected well. This demands a well-constructed microstructure in the catalyst layer (CL). Herein we design and optimize a cathode CL for a direct ammonia fuel cell (DAFC) using a perovskite oxide as the catalyst to reduce reliance on platinum group metals (PGMs). The effects of tailoring carbon, ionomer, and polytetrafluoroethylene (PTFE) content in cathode CLs (CCLs) were explored, and several DAFCs were tested. Using the same catalyst and operating conditions, the lowest maximum current density and peak power density obtained were 85.3 mA cm-2 and 5.92 mW cm-2, respectively, which substantially increased to 317 mA cm-2 and 30.1 mW cm-2 through proper carbon, ionomer, and PTFE optimization, illustrating the importance of an effective three-phase interface. The findings reveal that despite employment of an active catalyst for oxygen reduction at the cathode site, the true performance of the catalyst cannot be reflected unless it is supported by proper design of the CCL. The study also reveals that by optimizing the CCL, similar performances to those of Pt/C-based CCLs in literature can be obtained at a cost reduction.

Automated summary

To maximize fuel cell performance, a well-constructed microstructure in the catalyst layer (CL) is crucial for the effective transportation of electrons, ions, and reactants. In this study, a cathode CL for a direct ammonia fuel cell (DAFC) was designed and optimized using a perovskite oxide catalyst to reduce reliance on platinum group metals (PGMs). The results showed that the carbon, ionomer, and polytetrafluoroethylene (PTFE) content in the cathode CLs (CCLs) had a significant impact on the performance of the DAFCs. By optimizing these components, the maximum current density and peak power density were substantially increased, highlighting the importance of an effective three-phase interface.