Mechanistic switching in carbon paper supported Fe, Ni, and Mn-doped CoP nanosheets for efficient OER via DHS-OPM pathway

Fe@CoP-NSs/CP is synthesized and shows superior OER activity (272 mV at 10 mA cm⁻²). • DFT reveals Fe doping optimizes the d -band center (-1.92 eV) and adsorption energetics of Fe@CoP-NSs/CP. • DHS-OPM on Fe-Co sites of Fe@CoP-NSs/CP achieves a low overpotential of 0.35 V, outperforming AEM. • Fe@CoP-NSs/CP exhibits excellent stability over 30 h tested by chronoamperometry. • Machine learning identifies TM-OOH* and RDS as key predictors of catalytic efficiency (ROC-AUC up to 0.99). The oxygen evolution reaction (OER) remains a critical bottleneck for efficient oxygen production via water splitting due to its sluggish kinetics and high overpotential. Herein, we systematically investigated the OER mechanism on 3d transition metal-doped (Iron, Nickle, and Manganese) and pristine cobalt phosphide nanosheet carbon paper supported (Fe@CoP-NSs/CP, Ni@CoP-NSs/CP, Mn@CoP-NSs/CP, and CoP-NSs/CP) through a density functional theory (DFT) and experimental approach. The DFT calculations reveal that doping modulates the electronic structure of Fe@CoP-NSs/CP among the investigated systems exhibiting a d-band center closest to the Fermi level (-1.92 eV), leading to optimized adsorption energetics for key intermediates. Mechanistic mapping identifies the Dual Hetero-Site Oxide Path Mechanism (DHS-OPM) as the dominant pathway. In this mechanism, Fe-Co bimetallic sites achieve a remarkably low overpotential of 0.35 V, significantly outperforming the Adsorbate Evolution Mechanism (AEM). Experimentally, Fe@CoP-NSs/CP shows superior OER activity with an overpotential of 272 mV at 10 mA cm −2 and a Tafel slope of 47.4 mV dec −1 , with excellent stability over 30 h. Furthermore, supervised machine learning identifies TM-OOH* and rate-determining step (RDS) energies as the key predictors of catalytic efficiency, achieving ROC-AUC values up to 0.99. This work establishes a DFT-driven mechanistic framework, demonstrating that Fe@CoP-NSs/CP provides a highly efficient and durable pathway for OER. Download: Download high-res image (185KB) Download: Download full-size image