Synergistic Dual‐Defect Engineering in Amorphous‐Nanocrystalline Heterostructures for Accelerated Oxygen Evolution

ABSTRACT Defect engineering has been widely demonstrated as an effective strategy for enhancing the activity of OER metal catalysts, among which the introduction of twin boundaries (TBs) has proven particularly efficient. However, single‐type defects offer limited performance enhancement. Achieving synergistic catalytic improvement through multiple defects, although maintaining a simple and scalable synthesis route, remains a significant challenge. Here, we propose a dual‐defect synergistic engineering strategy by integrating amorphous‐nanocrystalline heterojunctions (ANHs) with TBs. This architecture is achieved via an innovative combination of nanosecond laser‐ablated carbon paper as a substrate and pulsed electrodeposition to fabricate a NiFeMo electrocatalyst. The resulting catalyst exhibits outstanding OER performance in alkaline media, demonstrating an overpotential of merely 196 mV at 10 mA cm −2 . Notably, it also achieves an exceptionally low Tafel slope of only 18.9 mV dec −1 , indicative of accelerated reaction kinetics. In situ Raman spectroscopy coupled with DFT calculations reveals that the ANHs and TBs act synergistically during OER. Distinct active species spontaneously migrate to energetically favorable defect sites with minimized energy barriers, thereby reducing the energy barrier of the rate‐determining step and significantly enhancing the reaction rate. This work provides a cost‐effective and facile dual‐defect engineering strategy, offering new insights into defect synergy for the rational design of high‐performance OER electrocatalysts.