Asymmetric TiS1O1N2 site for interfacial polarization with improved NO3−-to-NH3 photoreduction†

The efficiency of photocatalytic ammonia production is limited by insufficient active sites and sluggish interfacial charge transfer in photocatalysts. To address this, a titano-oxide phthalocyanine monatomic layer (TiOPc) is modified onto the face-centered cubic structured CdIn₂S₄via a hydrothermal process, significantly increasing the number of active sites. The close proximity of CdIn₂S₄ and TiOPc creates a local interface with an asymmetric configuration, resulting in a pronounced potential difference and an electron-rich TiS₁O₁N₂ polarization site. This configuration facilitates rapid charge transport between the two materials through the interfacial Ti–S bond. Profiting from these properties, TiOPc/CdIn₂S₄ delivers an impressive NH₃ formation rate of 2572.8 μmol g⁻¹ h⁻¹ and an apparent quantum efficiency achieving 7.16%, 6.86%, 4.12%, 2.13%, 1.86% and 1.15% at 400, 450, 500, 550, 650 and 700 nm, respectively. This study offers a practical method for designing symmetry breaking structures and establishing strongly coupled interfaces to enhance photocatalytic performance.