Research On The Construction And Environmental Purification Performance Of Niobium-based Functional Nanomaterials

In this paper,niobium-based nano sheets and nanotubes are used as basic structural units,and they are loaded and doped with different metal components to synthesize a series of new niobium-based nano-functional composite materials.Study the effects of loading and doping on the physical and chemical properties of niobium-based nanosheets and nanotubes,and apply them to the removal of organic pollutants in the energy and environmental fields.Investigate the structure-function relationship between the properties of nanocomposites and their performance.The main contents are summarized as follows:(1)WO3/HTiNbO5 and Fe2O3/HNbWO6 nanosheet composites with heterostructures were successfully synthesized by simple hydrothermal method and exfoliation-restacking method,respectively,using niobium-based HTiNbO5 and HNbWO6 nanosheets as basic structural units.Rhodamine B(RhB)as probe molecule was used to explore their photocatalytic degradation effect on organic compounds.Two-dimensional niobium-based nanosheets are a kind of semiconductor materials with large specific surface area and easy surface modification.By modifying them,the synergistic coupling between host and guest can improve the response range of the composites to the spectrum and promote the separation and transmission of photogenerated electrons and holes,so as to enhance the photocatalytic activity of the composites.Compared with HTiNbO5 and HNbWO6 nanosheets,WO3/HTiNbO5 and Fe2O3/HNbWO6 nano sheet composites exhibited significantly higher degradation rates of RhB5 reaching 90.7%and 99.5%,respectively.The analysis of energy band structure and photocatalytic mechanism shows that the degradation of RhB by the two kinds of composite materials follows the Z-scheme heterogeneous structure degradation mechanism,which provides a new research idea for the rational design and construction of highly efficient niobium-based nanocomposite photocatalytic materials with heterogeneous structure.(2)The regular H4Nb6017 nano tubes were synthesized by controlling the flocculation process of[Nb6O17]4-nanosheet so·.The slower the flocculation process,the more regular the morphology and structure of the synthesized nanotubes.The higher the specific surface area and the higher the content of surface hydroxyl functional groups of the H4Nb6O17 nanotubes,the higher breakthrough adsorption sulfur capacity for ethyl mercaptan.After nine adsorption-desorption cycles,H4Nb6O17 nanotubes can still maintain a desulfurization rate of 95.34%,and have good adsorption stability.(3)Different transition metal(Cr,Co/Fe,Cu)doped H4Nb6O17 nanotubes desulfurizers were synthesized by ion exchange-flocculation-calcination process.The strong interaction between metal oxygen species and H4Nb6O17 nanotubes can improve the structure,morphology and thermal stability of the nanotubes.It can also increase the specific surface area and pore volume of nanotubes,as well as form a rich hierarchical pore structure,and enhance the adsorption and activation of ethyl mercaptan gas.The adsorption between transition metal doped H4Nb6O17 nanotubes and ethyl mercaptan conforms to S-M bond coordination and the presence of metal oxygen species can significantly improve the redox ability of H4Nb6O17 nanotubes and promote the oxidation process of the adsorbed ethyl mercaptan on the nanotubes,generate corresponding metal sulfonates,sulfites and sulfates,and improve the removal ability of ethyl mercaptan by H4Nb6O17 nanotubes.However,the presence of these sulfur-containing oxidation products in nanotubes is also the main cause of nanotubes inactivation.Among the series of Cr doped H4Nb6O17 nanotubes,the highest sulfur breakthrough capacity is 34.95 mg·g-1,which is more than 2.5 times that of the H4Nb6O17 nanotubes calcined at 300?.In the Co/Fe co-doped H4Nb6O17 nanotubes,when the Co:Fe molar ratio is 0.3,the breakthrough adsorption sulfur capacity reaches 36.20 mg·g-1,which is more than 3.2 times that of the H4Nb6O17 nanotubes calcined at 450?.After the adsorption-desorption cycle regeneration experiment,the desulfurization rate of 96.55%can be maintained.Among the Cu-doped H4Nb6O17 nanotubes with different ion sources,the Cu-doped H4Nb6O17 nanotubes with the ion source CH3COO-have the highest breakthrough adsorption sulfur capacity,reaching 93.61 mg·g-1,which is more than 8.3 times that of H4Nb6O17 nanotubes calcined at 450?.Under the conditions of 50? and 6400 h-1 space velocity,the breakthrough adsorption sulfur capacity reached 103.6 mg·g-1.Finally,a corresponding desulfurization mechanism is proposed for the removal of ethyl mercaptan by metal-doped H4Nb6O17 nanotubes.The research results of this paper broaden the application of niobium-based materials in the field of photocatalysis and desulfurization,and provide a theoretical reference for the further development of niobium-based materials.Figure[78]Table[14]Reference[210]...