Generation Pathway of Hydroxyl Radical in Fe/N/C-Based Oxygen Reduction Electrocatalysts under Acidic Media

The identification of the generation pathway of (OH)-O-center dot radical during the oxygen reduction reaction (ORR) is critical because it determines which strategy should be adopted to minimize these corrosive species. In this way, researchers can develop a more stable Fe/N/C ORR catalyst or a catalyst layer in the proton exchange membrane fuel cells (PEMFCs). To date, this critical problem has still been unresolved. Herein, the generation of the (OH)-O-center dot radical during the acidic ORR was mimicked by using two known pathways, that is, the Fenton (and Fenton-like) and the electrochemical reduction of H2O2(H2O2-ECR) process. The latter was determined as the main generation pathway of (OH)-O-center dot radical below 30 degrees C. As the temperature surpassed 30 degrees C, the H2O2-ECR process began to lose its dominance because of the appearance of a third so-far unknown generation pathway. This work lays a basis for future development of radical elimination strategies to stabilize a Fe/N/C ORR catalyst or a catalyst layer in PEMFCs.

Automated summary

The main generation pathway of (OH)-O· radical during the acidic ORR was identified as the electrochemical reduction of H2O2 process, but a third unknown pathway appeared above 30 degrees Celsius, which provides a basis for developing radical elimination strategies to stabilize Fe/N/C ORR catalysts or catalyst layers in PEMFCs in the future.