One-Step Construction of SrTiO₃-TiO₂ Interfaces for Efficient NO Removal via Visible-Light Photocatalysis

The development of visible-light-responsive photocatalysts for effective nitrogen oxide (NO_x) abatement is critical for addressing urban air pollution. In this study, SrTiO₃/xTiO₂ (with x being the molar ratio of Ti over Sr) heterojunction photocatalysts were synthesized via a facile one-step precipitation method, involving ethanol-mediated precursor coordination, mild alkaline induction, and subsequent thermal activation. This approach enabled the direct incorporation of TiO₂ into the SrTiO₃ framework with tunable Ti precursor ratios, facilitating precise control over the heterojunction interface and significantly enhancing visible-light absorption. The composites were specifically designed to target the photocatalytic removal of nitric oxide (NO), which is the most reactive and dominant component of NO_x pollutants. Structural, morphological, and optical characterizations confirmed the successful formation of the SrTiO₃/TiO₂ heterojunction with intimate interfacial contact and broadened light absorption range. Among the series, the SrTiO₃/2TiO₂ heterojunction demonstrated the highest NO removal efficiency (63.89%), the lowest NO₂ generation (8.45%), rapid reaction kinetics, and excellent stability across multiple cycles, significantly outperforming both pristine SrTiO₃ and TiO₂. The enhanced photocatalytic performance is attributed to improved interfacial charge separation and efficient charge transfer processes, which facilitate the generation of reactive oxygen species, primarily superoxide and hydroxyl radicals. This work highlights the effectiveness of the SrTiO₃/TiO₂ heterojunction, synthesized via a facile one-step route, as a promising candidate for visible-light-driven NO_x abatement and advanced photocatalytic air-purification technologies.