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 a 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. Magneto-optical characterization reveals 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 an external magnetic field, offering a new paradigm in spin-photoelectrocatalysis for sustainable hydrogen production.