Recently, the liquid-phase laser environment preparation and processing laboratory of the Institute of Solid State Physics, Hefei Institute of Material Science, Chinese Academy of Sciences, controlled growth of Mn-doped α-Fe2O3 nanocrystals and their selective adsorption to heavy metal ions New progress has been made in the study. Relevant work was published in Chemistry of Materials.
Atomic scale regulation of nanocrystal morphology and surface structure is crucial to the study of its dendrite-dependent physicochemical properties.In general, the morphology of nanocrystals is determined by the presence of exposed crystal planes with particular atomic arrangements and the different crystal planes exhibit different Of the electronic structure, which in turn confers different physicochemical properties on various morphologies of nanocrystals.
α-Fe2O3 is a naturally rich and thermodynamically stable semiconductor that has shown promising applications in photo-electrochemical water splitting, lithium-ion batteries, gas sensing and biotechnology, etc. At present, the research on α-Fe2O3 mainly focuses on In the α-Fe2O3 nanocrystalline morphology control and surface structure modification, in order to achieve the performance optimization through the exposure surface regulation. Solvothermal method is to achieve controlled preparation with different crystal plane α-Fe2O3 nanocrystalline common method, it mainly through Surfactant or organic molecule addition, thermodynamically regulate the related free energy of different crystal planes, and then control the growth rate of the crystal plane in order to achieve the regulation of the exposed crystal face of the iron oxide. In addition, when the elemental impurities are doped into α -Fe2O3 nanocrystalline lattice, the geometry and electronic structure of the nanocrystal will change accordingly, and the crystal plane and morphology can be controlled.However, few studies have been reported in this aspect.
For this reason, the high activity MnOx colloids prepared by the liquid-phase laser ablation method in the liquid-phase laser environment preparation and processing laboratory of solid as the doping source, the Mn doping with controlled crystal plane and preferred orientation growth was obtained by adjusting the colloidal concentration Hetero-α-Fe2O3 nanocrystals include isotropic polyhedral nanoparticles, {116} crystal plane-dominated saucer-like nanosheets and {001} plane-dominated hexagonal nanosheets (Figure 1 AF) The growth of α-Fe2O3 nanocrystal in the direction of '001' becomes slow and the crystal face of {001} increases continuously with the increase of ion doping concentration. In addition, the Mn ions are uniformly doped in the state of +2, +3 or +4 The results show that the concentration of doping Mn ions and valence states play a key role in the crystal plane regulation of α-Fe2O3 nanocrystals.
At the same time, the doped α-Fe2O3 nanocrystals with different exposed crystal planes show selective surface adsorption ability on Pb, Cd and Hg, and the selective hexagonal nanocrystals dominated by {001} crystal planes The films show a strong selective adsorption on Pb ions, while the {116} plane-dominated saucer-like nanosheets exhibit strong selective adsorption on Cd and Hg ions. The DFT theoretical calculations (Figure 1 JM) further demonstrate that α -Fe2O3 nanocrystals have crystal-surface-dependent adsorption properties, among which, Pb ions, Cd ions and Hg ions show the highest adsorption energies on {001}, {116} and {110} planes, respectively, 012} and {104} exposed surfaces are the weakly adsorbed energy planes of Pb, Cd and Hg ions, showing very weak adsorption capacity for the three heavy metal ions consistent with the experimental results. Selective adsorption properties.
In this work, α-Fe2O3 nanocrystals with different exposed crystal planes were prepared by doping sources obtained by liquid-phase laser ablation, which provided a new strategy for designing and synthesizing other nanocrystals with different exposed active crystal planes. The related physical and chemical properties depend on the support of technical materials.
The research work is supported by the State Key Basic Research and Development Program (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.
