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) ] (TM=Fe, Co, Ni, Ru) as templates, a special three-dimensional (3D) metal halogenide framework of [TM(2,2-bipy) ]Cu Br was designed with [Cu Br ] cluster as 4-connected node. These microporous materials feature narrow band gaps and stable visible light driven photocatalytic properties including water reduction to provide H 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.

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'-bipy] (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'-bipy]MX (M = Cu, Ag, X = Br, I). The compounds feature a three-dimensional anionic [MX] network composed of a one-dimensional [MX] chain based on MX 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.

With similar transition metal (TM) complex cations as structural directing agents (SDAs), six new hybrid lead bromides were synthesized and structurally characterized as [Co(2,2-bipy)]{[Co(2,2-bipy)]PbBr} (1), [Co(2,2-bipy)Br]PbBr (2), [TM(phen)]PbBr (TM = Co (3) and Ni (4)), [Co(2,2-bipy)]PbBr (5) and [Co(2,2-bipy)]PbBr·CHCN (6) with distinct structural types from zero-dimensional (0D) unit, one-dimensional (1D) chain to two-dimensional (2D) layer. Compound 1 contains the 0D {[Co(bipy)]PbBr} units built from the [PbBr] ring attached by three unsaturated [Co(2,2-bipy)] complexes via Co-Br bonds. Under the direction actions of different SDAs, compounds 2 and 3-4 contain two different types of [PbBr] chains based on the same octahedral [PbBr] units but with distinct connecting manners, respectively. Using the same [Co(2,2-bipy)] as SDA, compound 5 reveals a 1D [PbBr] double chain, whereas compound 6 features a 2D complex [PbBr] layer. The UV/vis diffuse-reflectance measurements reveal that the title compounds feature tunable band gaps of 1.70-2.29 eV. Under the visible light irradiation, sample 6 exhibits efficient and stable photocatalytic degradation activities over organic pollutants, which mainly originates from the multi-electronic effects of the TM complex cations. A possible photocatalytic mechanism is also proposed based on the radical trapping experiments and electronic band structural calculations.

A three-dimensional (3D) metal-organic framework constructed from unprecedented Zn9O2(OH)2(pyz)12 (pyz = pyrazolate) clusters and Ni(salen)-derived linkers was reported. The MOF exhibits high catalytic activity for CO2 cycloaddition reactions with excellent...