Electrochemical advanced oxidation processes (EAOP) represent a promising strategy for the degradation of per- and polyfluoroalkyl substances (PFAS). However, the detailed mechanisms governing these transformations remain inadequately understood. While the process is initiated by electron transfer from the dissociated perfluorooctanoic acid (PFOA) anion to the anode, prior studies investigating subsequent chain-shortening reactions often neglect critical factors such as effects of applied potential, explicit water molecule interactions, surface-active site effects, and competing side reactions. In this study, we utilize quantum mechanical simulations and mechanistic analyses to investigate the degradation pathways of PFOA on various electrode surfaces. Specifically, we examine the effect of the presence of boron-doped diamond (BDD), SnO
2, Bi
2O
3, and RuO
2 electrodes to elucidate the role of material properties in modulating reaction pathways. Our results indicate that the initial chain-shortening step, decarboxylation, occurs without an energy barrier for all electrode materials except RuO
2, which exhibits a barrier of 0.9 eV. In contrast, the second chain-shortening step presents an energy barrier across all materials studied, suggesting it may be the rate-determining step during PFOA electrooxidation. Among the materials, BDD demonstrated the lowest barrier at 0.3 eV, significantly outperforming the bulk barrier of 1.2 eV, underscoring its efficacy as an electrode material. In comparison, Bi
2O
3 and SnO
2 exhibited barriers of 0.4 eV and 1.6 eV, respectively, with SnO
2 showing limited effectiveness for the second chain-shortening step. These findings provide mechanistic insight into the PFOA oxidation mechanism and highlights the impact of explicitly modeling the surfaces of various electrode materials, providing a foundation for designing optimal electrode materials for PFAS remediation.
