Structural Design Of Tungsten-based Nanomaterials And Their Applications In New Energy Fields

Energy is very important for human economic and social development,however,the world's major energy comes from the burning of fossil fuels.On the one hand,the burning of the fossil fuels results in the sharp consumption of non-renewable resources and on the other hand,the emission of a large amount of carbon dioxide causes serious environmental pollution.In order to ensure the sustainability of energy and environment friendly,renewable and clean energies such as wind energy,solar energy,geothermal energy,biomass energy ocean energy and fusion energy are more and more valued.However,the utilization and storage of the new energies depend on energy carrier.So,new energy carriers such as lithium ion battery?LIBs?,electrocatalytic hydrogen evolution reaction?HER?,supercapacitor and solar cell become new research hotspot.Because of high energy density,low cost,high security and abundant reserves,tungsten-based?W-based?nanomaterials show very high application value in new energy carrier region.In this thesis,we mainly focus on the structural design of tungsten-based nanomaterials and their applications in electrocatalytic HER and LIBs.?1?We synthesized WSe₂ monolayer nanosheets?MLNSs?by a solvent-assisted mechanically exfoliated method.And then,the WSe₂ MLNSs were annealed at700°C and 900°C to produce different amounts of selenium vacancies?Se-vacancies?.Our theoretical and experimental results reveal that these Se-vacancies can efficiently activate and optimize the originally inertial basal planes of the WSe₂ MLNSs.As expected,the optimized catalyst exhibits efficient electrocatalytic HER.?2?A general solvothermal route was used to synthesize a uniform W-based organic-inorganic hybrid precursor,WOx-EDA nanobelts.And then,the oxygen vacancies?O-vacancies?rich one-dimensional mesoporous W₁₈O₄₉ nanoblets(m-W₁₈O₄₉ NBs)are obtained by calcining the organic-inorganic precursor under H₂/Ar atmosphere.Charging-discharging performance test of the sample after calcination has been performed.m-W₁₈O₄₉ NBs electrode exhibits an ultrahigh initial Coulombic efficiency of 96.3%and at the same time it also displays higher specific capacity,better cycling stability and excellent rate capability.The excellent lithium storage performance of the m-W₁₈O₄₉9 NBs can be ascribed to the unique microstructure and rich O-vacancies.