RESUMO
By using transition-metal (TM) complex cationic dyes as structure-directing agents and photosensitizers, a series of inorganic-organic hybrid metal halides, namely, [TM(2,2'-bipy)3]AgPb2I7 [TM = Ni (1), Co (2) and Zn (3)], [Co(2,2'-bipy)3]CuPb2Br7 (4) and [TM(2,2'-bipy)3]AgPb2Br7 [TM = Ni (5) and Fe (6)], have been solvothermally prepared and structurally characterized. Compounds 1-3 feature 1D [AgPb2I7]2- chains built from the condensation of [Ag2I6] dimers and [Pb4I14] tetramers, and compounds 4, 5 and 6 contain similar 1D [CuPb2Br7]2- and [AgPb2Br7]2- chains, respectively. UV-Vis diffuse reflectance measurements reveal narrow band gaps of 1.75-2.18 eV for compounds 1-6, which lead to efficient and stable photocatalytic degradation activities over organic pollutants under visible light irradiation. Among the title compounds, sample 5 shows the highest photocatalytic degradation activity. The possible mechanism for their stable photocatalytic activities is proposed based on the experimental and theoretical studies.
RESUMO
With mixed transition-metal (TM) complex, alkali-metal cations, or halogen anions as structure-directing agents, two types of two-dimensional (2D) layered inorganic-organic hybrid silver bromides were prepared and structurally characterized as K[TM(2,2-bipy)3]2Ag6Br11 (TM = Ni (1), Co (2), Zn (3), Fe (4)) and [TM(2,2-bipy)3]2Ag13Br17 (TM = Ni (5), Co (6), Zn (7), Fe (8)). Compounds 1-4 feature 2D microporous anionic [Ag6Br11]5- layers composed of [Ag3Br7] secondary building units based on AgBr4 tetrahedral units, and compounds 5-8 contain 2D [Ag13Br16]3- layers built from the one-dimensional complex [Ag8Br12] and [Ag5Br8] chains. The photosensitization of TM complex dyes led to the narrow semiconducting behaviors with tunable band gaps of 1.73-2.71 eV for the title compounds, which result in excellent and stable photocatalytic degradation activities over organic pollutants under visible-light irradiation. The studies of photocatalytic mechanism based on radical-trapping experiments and electronic band structural calculation show that the TM complex cations play important roles in the photocatalytical activities and photochemical stabilities due to their excellent separating abilities for photogenerated carriers. This technique affords one new type of visible-light-driven photocatalyst and facilitates the integration of 2D layered materials and semiconducting photocatalytic properties into one hybrid d10 TM halogenide.
