Insights into the Proton-Coupled Electron Transfer Mechanism in Fuel Cells

Proton-coupled electron transfer (PCET) is not only an important fundamental process in energy systems but also a pivotal factor in enhancing electrocatalytic functions in fuel cells (FCs). This article investigates the PCET mechanism in low-temperature (300-500 °C) protonic ceramic fuel cells, focusing on its role in catalyzing the hydrogen oxidation reaction and the oxygen reduction reaction. Our findings reveal that PCET significantly enhances the electrocatalytic activity by mitigating polarization losses, reducing charge-transfer resistance by 1 to 2 orders of magnitude, and thereby accelerating the reaction kinetics compared to scenarios without PCET. Importantly, changes in relaxation time upon proton injection evidence the robustness of PCET. The marked reduction in activation energy to 0.31 eV further illustrates how PCET overcomes energy barriers, facilitating more efficient reaction pathways. These insights highlight the critical role of PCET in optimizing the electrocatalytic performance of FCs, underscoring its significant importance in advancing FC technology.