Non‐Determining Step Matters: Unveiling the Synergistic Mechanism of High‐Entropy (NiCoFeMoIn) ₃ S ₄ Catalysts for Enhanced Oxygen Production in Seawater

Abstract High‐entropy materials (HEMs) are a highly promising class of electrocatalysts for the oxygen evolution reaction (OER). However, a comprehensive understanding of their synergistic catalytic mechanisms remains elusive, limiting the development of efficient catalysts. In this work, the catalytic performance of the HEMs (NiCoFeMoIn) 3 S 4 for oxygen evolution in alkaline seawater is investigated, which exhibited excellent performance, achieving an ultralow overpotential of 254/275 mV in alkaline freshwater/seawater at a current density of 100 mA cm −2 . Experiments revealed the involvement of multiple metal sites in the OER processes and the migration of oxygen‐related intermediates among them. Density functional theory (DFT) calculations demonstrated a significant discrepancy between the energy barrier of the rate‐determining step (RDS) and the experimental data. Both results challenge the prevailing view that focuses solely on the RDS in understanding HEMs catalysis. While the Monte Carlo simulations, informed by DFT data and synergistic interactions in the non‐determining step (NDS), revealed 50 mV reduction in overpotential and a 50% increase in catalytic efficiency. These simulations align well with the experimental results, further confirming the importance of NDS. The work provides a novel insight of the synergistic catalytic mechanisms and underscores the non‐negligible role of NDS on HEMs catalysis in electrochemical reactions.