Pr6O11-driven electron modulation via d–f orbital hybridization for alkaline seawater electrolysis

Abstract

Rare-earth modulation provides an effective route for tuning the electronic structure of transition metals for oxygen release. However, the role of d–f orbital hybridization in governing the interfacial charge behavior in electrochemical oxygen evolution reactions (OERs) remains unclear. Herein, an in situ electrochemical reconstruction strategy is developed to transform Pr-doped CoP/Fe₂P nanoparticles into a three-dimensional CoFeOOH nanosheet network decorated with Pr₆O₁₁ clusters under operating conditions, where Pr₆O₁₁ acts as an electron modulator to regulate the interfacial charge behavior. The strong d–f orbital hybridization between the Pr 4f and Co/Fe 3d orbitals delocalizes the electrons and accelerates the interfacial charge transfer, enhancing the oxygen evolution kinetics. Consequently, charge redistribution between Pr₆O₁₁ and CoFeOOH modulates the electronic structure to optimize intermediate adsorption and lower the energy barrier. Meanwhile, the dynamically evolved Pr₆O₁₁ clusters modulate the surface adsorption energetics, making OH⁻ adsorption more favorable than Cl⁻ and thereby enhancing resistance to chloride corrosion under seawater conditions. The Pr₆O₁₁–CoFeOOH electrode exhibits an improved OER performance, requiring overpotentials of 223 and 233 mV at 100 mA cm⁻² in alkaline freshwater and simulated seawater, respectively. When applied in a Pt/C‖Pr₆O₁₁–CoFeOOH anion-exchange membrane electrolyzer, the system consistently delivers 500 mA cm⁻² at 1.7 V and operates stably for over 500 hours. This study reveals a feasible strategy for constructing robust electrocatalysts through d–f orbital hybridization, enabling efficient electrochemical energy conversion.