Institute of Solid State Physics, Iron Oxide Common Name Chinese Academy of Sciences, Laboratory of Preparing and Processing Liquid-Phase Laser Environments, Institute of Solid State Physics, Chinese Academy of Sciences, Controlled Growth of Crystal Surfaces of Mn-Doped α-Fe2O3 Nanocrystals and Their Crystal Surface-dependent Selective Adsorption for Heavy Metal Ions New progress Iron Oxide Crystal was made in the research and related work was published on the Chemistry of Materials.
The regulation of the morphology Iron Oxide Charge and surface structure of nanocrystals at the atomic scale is crucial for the investigation of their crystal surface-dependent physicochemical properties. In general, the morphology of nanocrystals is determined by the exposed crystal planes with a particular atomic arrangement, and different crystal planes will exhibit different electronic structures, which in essence will impart different physical Boric Acid Flakes and chemical properties to various topographic nanocrystals.
α-Fe2O3 is a naturally abundant Melamine Powder and thermodynamically stable semiconductor. It exhibits good prospects in photoelectrochemical decomposition of water, lithium ion batteries, gas sensing, and biotechnology. At present, the research on α-Fe2O3 mainly focuses on the morphology regulation Sodium Hexametaphosphate and surface structure modification of α-Fe2O3 nanocrystals, in order to optimize the performance through the regulation of the exposed surface. The solvothermal method is a common method for the controlled preparation of α-Fe2O3 nanocrystals with different crystal planes. It controls the thermodynamically related free energy of different crystal planes, mainly through the addition of surfactants or organic molecules. The growth rate of the surface to achieve the regulation of the exposed surface of iron oxide. In addition, when the element impurities are doped into the α-Fe2O3 nanocrystalline lattice, the geometric and electronic structures of the nanocrystals will change accordingly, and the crystal surface and morphology can also be controlled. However, little research has been reported in this area.
For this reason, the highly active MnOx colloid prepared by the liquid phase laser ablation method was used as the doping source in the solid-liquid laser environment preparation and processing laboratory, and the Mn doping with controllable crystal surface and preferred orientation growth was obtained by adjusting the colloid concentration. Heterogeneous α-Fe2O3 nanocrystals: includes isotropic polyhedral nanoparticles, {116} crystallographic plane dominated UFO-like nanosheets, and {001} crystallographic plane-dominated hexagonal nanoplatelets (Figure 1 AF). It was found that with the increase of the concentration of Mn ions, the growth of α-Fe2O3 nanocrystals in the [001] direction became slow, and the {001} exposed crystal surface increased continuously. In addition, Mn ions are uniformly doped in the +, +3, or +4 valence state in the lattice planes of the α-Fe2O3 lattice dominated by different crystal planes (Fig. 1 GI). The results show that the concentration and the valence states of the doped Mn ions play a key role in the regulation of the crystal face of the α-Fe2O3 nanocrystals.
At the same time, these doped α-Fe2O3 nanocrystals with different exposed crystal planes exhibited crystal surface-dependent selective surface adsorption capacity for three heavy metal ions, Pb, Cd, and Hg. Among them, the {001} crystal plane-dominated hexagonal nanoplatelets exhibited strong selective adsorption of Pb ions, while the {116} crystallographic plane dominated the flying disklike nanoplatelets exhibited strong selective adsorption of Cd and Hg ions. The DFT theoretical calculation (Fig. 1 JM) further demonstrated that the α-Fe2O3 nanocrystals have crystal surface-dependent adsorption properties. Among them, Pb ion, Cd ion, and Hg ion exhibit the highest adsorption energy on the {001}, {116}, and {110} crystal planes, respectively, while the {012} and {104} exposed surfaces of the polyhedral nanoparticles are Pb ions. The weak adsorption surface of Cd ion and Hg ion exhibited a very weak adsorption capacity for three heavy metal ions consistent with the experimental results, and interpreted the selective adsorption performance of the crystal plane from the theoretical level.
In this work, the α-Fe2O3 nanocrystals with different exposed crystal faces were prepared by doping source obtained by liquid-phase laser ablation technology, which provided a new strategy for designing and synthesizing other nanocrystals with different exposed active crystal faces. Dependent on the correlation of the physical and chemical properties of research provides technical support.
The research work was supported by the National Key Basic Research Development Plan (973 Program) of the Ministry of Science and Technology, the National Natural Science Foundation of China, and the Innovation Team Project of the Chinese Academy of Sciences.
