Tuning α‐MnOOH Formation via Atomic‐Level Fe Introduction for Superior OER Performance

Abstract The arrangement of atoms in the catalyst directly impacts the catalytic performance. Herein, a heteroatom doping strategy is found as an effective approach for the regulation of MnO ₂ crystal reconstruction during the oxygen evolution reaction (OER), thereby ensuring and optimizing the performance of the catalyst. Real‐time tracking of dynamic surface reconstruction reveals that δ‐MnO ₂ transforms into the less active γ‐MnOOH phase, while single‐atom Fe doping facilitates the formation of highly active α‐MnOOH phase. The formation of asymmetric Fe─O─Mn bonds induce lattice distortions of MnO ₂ and promote electron transfer from Fe to Mn with an increase in the Mn ³ ⁺ content, which is conducive to intensifying oxygen spillover and is a crucial factor for OER activity. Theoretical calculations also demonstrate that the effective active sites regulated in the representative catalyst of α‐MnOOH can reduce the energy barrier for a crucial step during the OER process (the *O to *OOH transition), thus significantly enhancing catalytic performance. The typical catalyst achieves the successful regulation of crystal reconstruction processes through heteroatom doping, which holds significant implications for developing a new class of catalysts, not limited to the OER catalysts reported in this study.