Novel Three-Dimensional Semiconducting Materials Based on Hybrid d¹⁰ Transition Metal Halogenides as Visible Light-Driven Photocatalysts

Abstract

The development of new visible light-driven photocatalysts based on semiconducting materials remains a greatly interesting and challenging task for the purpose of solving the energy crisis and environmental issues. By using photosensitive [(Me)₂-2,2'-bipy]²⁺ (1,1'-dimethyl-2,2'-bipyridinium) cation as template, we synthesized one new type of inorganic-organic hybrid cuprous and silver halogenides of [(Me)₂-2,2'-bipy]M₈X₁₀ (M = Cu, Ag, X = Br, I). The compounds feature a three-dimensional anionic [M₈X₁₀]^2- network composed of a one-dimensional [M₈X₁₂] chain based on MX₄ tetrahedral units. The photosensitization of organic cationic templates results in narrow band gaps of hybrid compounds (1.66-2.06 eV), which feature stable visible light-driven photodegradation activities for organic pollutants. A detailed study of the photocatalytic mechanism, including the photoelectric response, photoluminescence spectra, and theoretical calculations, shows that the organic cationic template effectively inhibits the recombination of photoinduced electron-hole pairs leading to excellent photocatalytic activities and photochemical stabilities.