Oxygen Vacancy Engineering Enables Efficient Photocatalytic Nitrogen Fixation Over Layered Bismuth Titanate

ABSTRACT Oxygen vacancy engineering is widely regarded as an effective strategy to enhance the photocatalytic performance of oxide semiconductors; however, its synergistic effects on band structure and interfacial charge carrier behavior remain insufficiently understood. In this work, layered Aurivillius‐phase Bi 4 Ti 3 O 12 was selected as a model photocatalyst, and a series of oxygen‐vacancy‐rich Bi 4 Ti 3 O 12 (Ov‐BTO) materials were successfully synthesized via a NaBH 4 reduction method. Multiple characterization results reveal that the introduction of oxygen vacancies not only induces local lattice distortion and electronic density redistribution, but also leads to the in situ formation of a small amount of metallic Bi. Band structure analysis indicates that oxygen vacancies slightly narrow the band gap and shift both the Fermi level and the conduction band position upward, which is favorable for the generation and migration of photogenerated electrons. Further investigation shows that an Ohmic contact is formed between metallic Bi and Ov‐BTO, creating a built‐in electric field at the interface that significantly promotes the efficient separation of photogenerated charge carriers. Benefiting from these synergistic effects, the optimal Ov‐BTO sample exhibits markedly enhanced photocatalytic nitrogen fixation performance under simulated solar light irradiation, achieving an NH 4 + production rate of 562.9 µmol L −1 ·g −1 ·h −1 , approximately 3.2 times higher than that of pristine BTO, along with good stability. This work provides new insights into the rational design of high‐performance oxide photocatalysts from the perspective of the synergy between defect engineering and interfacial regulation.