Synergistic Spin-State Modulation in Co/N co-Doped TiO₂ for Enhanced Photoelectrocatalytic Oxygen Evolution under External Magnetic Fields

Abstract

The oxygen evolution reaction (OER) remains a major kinetic bottleneck in alkaline water splitting, necessitating innovative approaches to enhance efficiency. This study presents a novel spin-state modulation strategy in Co/N co-doped TiO₂, integrating oxygen vacancy engineering and ferromagnetic Co doping to enable spin-polarized charge transfer. Under low external magnetic field, the photoelectrocatalytic (PEC) OER performance exhibits ~1.6 fold enhancement, surpassing conventional spin-catalysis strategies. Nitrogen doping extends light absorption into the visible spectrum, further improving charge carrier dynamics. Magnetooptical characterizations reveal prolonged excited carrier lifetimes and strong spin polarization effects, validated by density functional theory (DFT) calculations, confirming the emergence of spin-polarized electronic states. This work establishes a scalable, contactless energy transfer approach via external magnetic field, offering a new paradigm in spin-photoelectrocatalysis for sustainable hydrogen production.