Atomic Exploration of the Fluorination-Driven Structural Rearrangement of Carbon Electrocatalysts toward Efficient Oxygen Reduction Reactions
Yang Li, Zhen Cao, Cailing Chen, Guoxiang Zhao, Edy Abou‐Hamad, Zhi‐Peng Wu, Zirui Wang, Qiaohong Li, Magnus Rueping, Yu Han, Luigi Cavallo, Huabin Zhang
Abstract
The atom arrangement in carbon electrocatalysts is crucial for enhancing the intrinsic activity toward oxygen reduction reactions (ORRs), a key process in multiple renewable energy systems. However, the challenge of designing electrocatalysts with improved performance by manipulating atomic arrangement has been limited by synthetic constraints and a lack of understanding of the catalytic phase formation. Herein, we gain atomic-level insight into the origin of a highly active site by creating a model catalyst with a heteroatom-decorated carbon matrix of a specific configuration. The introduction of fluorine (F) during the synthesis of the nitrogen (N)-decorated carbon matrix induces structural rearrangement, converting most pyrrolic-N (P r -N) into highly stable graphitic-N (G-N), thereby achieving a N configuration predominantly composed of pyridinic nitrogen (P y -N) and G-N. The multidopant synergistic effect of F, P y -N, and G-N causes a destabilized π-conjugated electron network of the carbon matrix, resulting in a more localized electronic structure. As a result, multiple dopant configurations with high ORR activity have been explored, among which the asymmetric P y -N and G-N configurations feature the lowest theoretical ORR overpotential, ultimately enabling the optimized F@NC catalyst to exhibit excellent oxygen reduction activity. This work establishes a foundation for the rational design of metal-free carbon-based electrocatalysts toward ORR.