Magnetic‐Field‐Stimulated Efficient Photocatalytic N2 Fixation over Defective BaTiO3 Perovskites

Efficient coupling solar energy conversion and N2 fixation by photocatalysis has been shown promising potentials. However, the unsatisfied yield rate of NH3 curbs its forward application. Defective typical perovskite, BaTiO3, shows remarkable activity under an applied magnetic field for photocatalytic N2 fixation with an NH3 yield rate exceeding 1.93 mg L−1 h−1. Through steered surface spin states and oxygen vacancies, the electromagnetic synergistic effect between the internal electric field and an external magnetic field is stimulated. X‐ray absorption spectroscopy and density functional theory calculations reveal the regulation of electronic and magnetic properties through manipulation of oxygen vacancies and inducement of Lorentz force and spin selectivity effect. The electromagnetic effect suppresses the recombination of photoexcited carriers in semiconducting nanomaterials, which acts synergistically to promote N2 adsorption and activation while facilitating fast charge separation under UV‐vis irradiation. A model ferroelectric photocatalyst, BaTiO3, was treated with NaBH4 to introduce surface oxygen vacancies (Ov‐BTO). The resultant material offers spin‐polarized regulation and an increased internal electric field (IEF). The function of Ov‐induced photocatalytic activity under an external magnetic field is explored and the positive effect of the external magnetic field phenomenon demonstrated on photocatalytic N2 fixation.