Synthesis Of Magnesium-Carbon Materials And Zinc Stannate Nanomaterials And Mechanisms With Hydrogen

Hydrogen energy as a kind of clean energy is more appreciated.In order to promote the use of hydrogen energy,how to produce hydrogen effectively,to use hydrogen efficiently,to store hydrogen safely and economically,and also to detect hydrogen sensitivity and rapidity have been the urgent problems.Hence,a major focus of the development of hydrogen energy will be on exploring new hydrogen storage material with a high-energy density,high storage capacity and safe and convenient to use.Moreover,the development of the hydrogen sensing material with high sensitivity,fast response and safety cleanliness is also an important aspect of popularization and application of hydrogen energy source.In order to solve the above problems,the main work of this paper is to study the preparation of high-capacity hydrogen storage materials and hydrogen storage mechanism,and the synthesis of high-performance hydrogen-sensitive materials and gas-sensing mechanism,as follows:The C60/Mg and CNTs/Mg nanocomposites had been obtained through a simple high-energy ball-milling process,the microstructure,composition and hydrogen storage properties of the prepared materials were studied.The results from PCT test showed that the as-obtained C₆₀/Mg displayed a much enhanced hydrogen storage capacity of 12.5 wt%hydrogen under the condition of 300 ^oC and 45 bar.In addition,the hydrogen storage mechanism had been studied by the theoretical calculation and the correlated experimental analyses.The hydrogen absorption process of CNTs/Mg composites can be carried out at 280^oC and very low hydrogen pressure?2.5 bar?,and the hydrogen storage capacity of composites was up to 6.90 wt.%.At the same time,carbon nanotubes had excellent supporting effect on the whole material,and the morphology of the CNTs/Mg composites was unchanged after several cycles of hydrogen absorption and desorption.The synthesis and hydrogen sensing properties of ZnSnO₃ and its composites were studied.The well-defined individual two crystal phases ZnSnO3?orthorhombic?orth?and face-centered cubic?fcc?phases?had been successfully synthesized assisted by a ZnO inducing template in an identical solution.The morphology,structure,formation mechanism,hydrogen sensitivity and mechanism of the two materials were studied by X-ray powder diffraction,scanning electron microscopy,transmission electron microscopy and UV-Vis absorption spectroscopy.Moreover,the fcc-ZnSnO₃ hollow microspheres and orth-ZnSnO₃solid microspheres exhibited porous microspherical morphologies constructed by the tiny nanograins,resulting in their high sensitivities and low optimum temperature to hydrogen.For example:the response to 100 ppm hydrogen of fcc-ZnSnO3 hollow microspheres was 12.0 at260 ^oC.On the basis of the above work,ZnO/ZnSnO₃ nanoarrays with a hetero-epitaxial growth relation and core-shell structure had been synthesized using ZnO nanorods as the template and reactant.Because of the Z-type band structure formed by two kinds of epitaxial semiconductors,a reinforced spatial separation of electrons and holes had been realized,which resulted in more negative oxygen ions?O₂^-and O^-?generated on the composite's surface.Therefore,the gas sensor based on ZnO/ZnSnO₃ nanoarrays showed highly gas responses to various gases.The results showed that the hetero-epitaxial growth ZnO/ZnSnO3nanoarrays had a response of 13.0 to the lower concentration of 30 ppm hydrogen,and the response and recovery time were within 20 s.