Bandgap Engineering of Copper(I) Iodide Hybrid Materials for NIR-II Emission and Photocatalytic H₂O₂ Production

Near-infrared (NIR) luminescent materials are of great importance for photonics and energy applications, yet the realization of efficient emission in the NIR-II window (1000-1700 nm) remains challenging and requires precise bandgap engineering. Herein, we advance the cationic-ligand engineering strategy to construct two novel AIO-type CuI based hybrid materials with narrow bandgaps (∼1.6 eV). These compounds exhibited strong visible-light absorption, and NIR-II emission peaked at 1000-1025 nm with the highest photoluminescence quantum yield reaching 7.7%. Their emission mechanism was revealed by comprehensive photophysical and computational studies. Owing to their excellent visible-light harvesting ability, compound 1 demonstrated an efficient photocatalytic production of H₂O₂ from O₂ and H₂O without sacrificial agents, with a production rate of 1000 μmol g^-1 h^-1. This work demonstrates that cationic-ligand design is a powerful tool for effectively tailoring optical bandgaps, enables enhanced emission efficiency, and integrates photocatalytic function, offering a versatile approach to multifunctional hybrid semiconductors.