Band Alignment in TiO ₂ /UiO‐67 S‐Scheme Heterojunction for Anti‐Interference Phosphate Sensing

Abstract Due to the high salinity, high background ions, and complex and changeable environmental conditions in seawater, the existing electrochemical sensors still have significant deficiencies in terms of selectivity, and anti‐interference ability. There is an urgent challenge to develop higher‐performance sensor materials and structures to meet the demands of marine environment monitoring. Precise regulation of band structures at heterojunction interfaces enables access to unique electrical and optical properties, thereby addressing key sensing challenges. Notably, S‐scheme heterojunctions with tunable contact barriers provide exceptional capability for interfacial energy‐level alignment. Building on this principle, the band structure of TiO 2 /UiO‐67 S‐scheme heterojunctions is engineered with physical gating as the trigger factor to optimize electrochemical sensing performance. The superior sensing performance originates from the tunable contact barrier of S‐scheme heterojunction, which not only regulates interfacial band alignment but also promotes efficient carrier separation. Mechanistically, this dual function synergistically enhances the S‐scheme charge transfer, generating a pronounced and specific response to phosphate even in seawater. As a result, the constructed sensor exhibits ultra‐low detection limit (43 p M ) and excellent resistance to interference in seawater for phosphate detection. This study provides new insights into the mechanistic comprehension and strategic adjustment of energy band engineering for sensing applications.