Novel 3D Semiconducting Open-Frameworks based on Cuprous Bromides with Visible Light Driven Photocatalytic Properties

Visible light driven photocatalysts based on crystalline microporous metal halogenides received much less attention compared with dense or composite oxide semiconductors. Using the well-known photosensitive transition metal-complexes [TM(2,2-bipy)₃ ]²⁺ (TM=Fe, Co, Ni, Ru) as templates, a special three-dimensional (3D) metal halogenide framework of [TM(2,2-bipy)₃ ]Cu₄ Br₆ was designed with [Cu₄ Br₄ ] cluster as 4-connected node. These microporous materials feature narrow band gaps and stable visible light driven photocatalytic properties including water reduction to provide H₂ and photodegradation of organic pollutants. The study of electronic band structure shows that the TM complexes effectively prevent the recombination of photo-induced electron/hole pairs leading to excellent photocatalytic activity and photochemical stability. This work represents the first 3D microporous metal halogenides used as visible light driven photocatalyst to provide hydrogen energy.