Environmental factors at electrochemical interfaces, such as the local electric field, are widely recognized as critical determinants of catalytic performance, which could strongly influence reaction pathways and kinetics. However, strategies that leverage these effects to precisely control catalytic activity are limited. In this study, using grand canonical potential density functional theory, we demonstrate that combining single-atom catalysts (SACs) with ferroelectric substrates is a powerful solution. The modified local electric field significantly weakens the adsorption of the *OH intermediate in the oxygen reduction reaction (ORR) on the FeN₄–C catalyst. By establishing a physical model, we reveal that the local electric field is primarily modified by surface charges induced by the applied potential and the intrinsic dipole moment of the substrate. Our findings highlight the significant role of local electric fields in tailoring catalytic mechanism, and pave the way for a promising substate engineering approach in the rational design of high-performance electrocatalytic devices.

Developing highly efficient oxygen evolution reaction (OER) catalyst for the acidic corrosive operating conditions is a challenging task. Herein, we report the synthesis of uniform RuO₂ clusters with ~ 2 nm in size via electrochemical leaching of Sr from SrRuO₃ ceramic in acid. The RuO₂ clusters exhibit ultrahigh OER activity with overpotential of ~ 160 mV at 10 mA·cm_geo⁻² in 1.0 M HClO₄ solution for 30-h testing. The extended X-ray absorption fine structure measurement reveals enlarged Jahn-Teller distortion of Ru-O octahedra in the RuO₂ clusters compared to its bulk counterpart. Density function theory calculations show that the enhanced Jahn-Teller distortion can improve the intrinsic OER activity of RuO₂.