Syntheses,Structures And Properties Of Bi/Pb-based Metal Halide Hybrids Containing Transition Metal-Phenanthroline Complexes

Metal halides have received enough attentions,inspired by their fascinating structural topologies and their unique physical or chemical properties.Among them,bismuth/lead-based halides are of particularly appealing due to the wide applications in semiconductivity,luminescence,photocatalysis and photoelectricity,etc.In recent years,the preparation of new metal halides with transition metal-organic cations has become an important research direction.Compared with the other types of templates（e.g.,organic amines,alkali metal/alkaline earth metal cations and metal aliphatic amine complexes）,transition metal–conjugated organic ligand complexes are optically active,and their introduction can provide the new self-assembly styles.Furthermore,the incorporation of second metal into the single metal bismuth/lead-based halide system not only may result in the complex structure,but also may induce some interesting physico-chemical properties.In this thesis,by utilizing[M（phen）₃]²⁺as templates,seven new bismuth/lead-based hybrid materials have been solvothermally synthesized and structurally characterized.The optical properties of selected compounds have also been studied.The compounds are listed as follows:[NH₄][Ni（phen）₃]Bi I₆（1）[NH₄][Co（phen）₃]Bi I₆（2）[Zn（phen）₃]Ag Bi I₆（3）[Fe（phen）₃]Ag₂Pb Br₆（4）[Ni（phen）₃]Ag₂Pb Br₆（5）[Ni（phen）₃]Ag₂Pb I₆（6）[Co（phen）₃]Ag₂Pb I₆（7）Compounds 1-3 are three iodobismuthate hybrids with[M（phen）₃]²⁺（M=Ni,Co,Zn）complex cations as template directing agents.Compounds 1 and 2 feature the typical[Bi I₆]^3-anions that isolated the[M（phen）₃]²⁺metal complexes and the in situ generation of NH₄⁺ions.Compound 3 is a new member of Ag-Bi-I family with the chain-typed[Ag Bi I₆]^2-anions.Hirshfeld surface analysis showed that the contributions from C-H…I and C-H…πin compound 1 were larger,which indicated that the cationic components are crucial in the stabilization of the structure.Solid-state UV–Vis diffuse reflectance studies showed that compounds 1–3 exhibit the semiconducting behavior with optical band gap values of 2.09 e V,1.98 e V and 2.08 e V,respectively.Next,we took compound 1 as an example to study the photocatalytic properties.Compound 1 dispalyed excellent visible-light-driven photocatalytic degradation of crystal violet（CV）with 95%degradation efficiency within 10 min.More importantly,it also has impressive cycling stability with the high degradation efficiency even after the 3 cycles.In addition,we further performed the band structure and density of states of compound 1 with the help of theoretical calculations,which showed that the charge transfer between inorganic and organic components may be the source of its excellent photocatalytic properties.Compounds 4-7 are a series of Ag-Pb-X（X=Br,I）compounds containing transition metal–phenanthroline complexes.Compounds 4-7 are isomorphic phases,and features the curve-like[Ag₂Pb X₆]^2-（X=Br,I）anions that are separated by[M（phen）₃]²⁺（M=Fe,Ni,Co）metal complexes.Hirshfeld surface analysis showed that the contributions of C-H…X and H…H in the compound were large which played important role in structural stability.Solid-state UV–Vis diffuse reflectance tests showed that compounds 4–7 exhibit the semiconducting properties with optical band gaps of 1.99 e V,2.74 e V,2.68 e V and 2.21 e V,respectively.Due to time limitation,we just studied the photoelectric conversion properties of compounds 4-6.Compounds 4–6 exhibited fast and effective photoelectric conversion behaviors under the alternate visible light irradiation.In addition,the compounds also displayed good reproducibility in the process of experiment,even after multiple cycles,the compound still exhibited stable photocurrent density.The photocurrent densities of compounds 4–6 is 0.03–0.4μA cm^-2.Theoretical analysis revealed that the conduction band of this series of compounds is mainly derived from C and N of organic cations,while the valence band is mainly composed of Fe,Ag and X.The results showed that both the photosensitive organic cations and the electron-rich inorganic components may play an important role in the optical band gaps,especially the former.The innovation of this thesis is that metal complexes as templates have been used to synthesize a series of bismuth/lead-based halides,and the compounds have been subjected to structure determination,Hirshfeld surface analysis,spectroscopic characterization and theoretical calculation.Furthermore,photocatalytic and photoelectric performance of selected compounds have been studied.The results showed that some of the obtained compounds have excellent photocatalytic and optoelectronic properties.This work provides useful information for the subsequent exploratory synthesize of metal halides that have excellent optical properties and the deep understanding of the relationship between structure and properties.