Shape-Controlled Synthesis Of Prussian Blue Analogues And Conversion To Nanoporous Composite Materials

It has been generally accepted that the properties of micro-/nanomaterials have been greatly influenced by their structures and morphologies. Therefore, shape-controlled synthesis has been considered to be an important approach which could acquire materials with outstanding properties. During recent years, Prussian blue and its analogous (PBAs) have been studied widely because of their unique properties and potential applications in many fields. In this paper, we have investigated the shape-controlled synthesis of some different PBAs and conjectured the morphological formation mechanism. Furthermore, we have successfully transformed these PBAs to nano-porous composites through thermal treatment.1. Prussian blue analogue K2Zn3[Fe(CN)6]2quasi square microplates:large-scale synthesis and their thermal conversion into magnetic nanoporous ZnFe2-xO4-ZnO compositesPrussian blue analogue (PBA) K2Zn3[Fe(CN)6]2·xH2O microplates were synthesized via solvothermal method in the mixed solvent of isopropanol and deionized water at120℃for24h. The as-synthesized products were identified as pure phase by XRD. FESEM and TEM images showed that single-crystalline quasi square microplates with fairly uniform morphology were successfully prepared. The average thickness and side length of the microplates were about160and750nm respectively. The effects of the ratio of (CH3)2CHOH/H2O in the reaction system and surfactant (polyvinyl pyrrolidone, PVP) on the morphology of products were investigated. The experimental results showed that PVP and solvent isopropanol played important roles in the formation of uniform microplates. Magnetic nanoporous ZnFe2-xO4-ZnO composite could be obtained from K2Zn3[Fe(CN)6]2·xH2O microplates after calcined at500℃. The composite showed high photocatalytic property in degradation of rhodamine B (RB) and could be easily separated from the reaction mixture through magnetic separation.2. Morphology control of monodisperse solid-solution PBA nanocubes at room-temperature and their conversion into magnetic nanoporous compositesFe-Co-Fe PBA, Ni-Co-Fe PBA and Cu-Co-Fe PBA were successfully synthesized by co-precipitation at room temperature. Trisodium citrate was used as ligand which could directly interact with metal ions. The as-synthesized products were identified as pure phase by XRD. FESEM and TEM images showed that single-crystalline nanocubes with fairly uniform morphology were successfully prepared. The average partical size were110nm,280nm and220nm respectively. The effects of temperature on the morphology of products were investigated. When the reaction temperature was80℃, the product of Ni-Co-Fe PBA changed to hierarchical architecture which may formed through non-classial crystallization and should be a mesocrystal which is in good agreement of Colfen’s definition. The mesocrystal should be formed by the oriented attachment of nanocubes. Magnetic nanoporous composite Coo.8Nio.2Fe2O4could be obtained from Ni-Co-Fe PBA after calcined at480℃. The composite showed high catalytic property in the oxidation of methylene blue (MB) with H2O2as oxidizing agent and could be easily separated from the reaction mixture through magnetic separation.When calined at500℃for2h, the composite changed to CoxNi1-xFe2O4/Co2O3, which indicated that different components could be obtained after calined at different temperatures.3. Synthesis of PBA Zn3[Fe(CN)6]2with octahedron structure and its thermal conversion into a nanoporous ZnFe2O4-ZnO compositePrussian blue analogue (PBA) Zn3[Fe(CN)6]2·nH2O octahedrons were successfully synthesized via co-precipitation at room temperature for24h. The as-synthesized products were identified as pure phase by XRD. SEM images showed that octahedral is the main morphology of product. The average particle size of the octahedron was about1μm. The effects of the surfactant (sodium dodecyl benzene sulfonate, SDBS) and reaction temperature on the morphology of products were investigated. The experimental results showed that SDBS and reaction temperature played important roles in the formation of the morphology of octahedral. Nanoporous ZnFeaO4/ZnO composite could be obtained from Zn3[Fe(CN)6]2·nH2O after calcined at500℃and the composite showed high photocatalytic property in degradation of rhodamine B (RB).