Sythesis Of Multi-metal Compounds Semiconductor Heterostructure And Their Photo(electro/thermal) Catavtic Performance

Solar is an almost unlimited energy.The energy crisis has promoted the development of solar energy catalytic conversion.How to use low intensity solar energy efficiently is a key point.In the field of solar energy conversion,too low efficiency and too strong light cannot be used practically.Efficient low intensity solar energy utilization has become an urgent problem.One approach is to develop materials that have effective solar-light utilization efficiency,low energy and economy cost,as well as efficient catalytic activities.The construction of heterostructure provides a potential solution.The purpose of this thesis is to select reasonable compound semiconductor materials.According to the different reaction,appropriate heterostructures were constructed to improve the intrinsic properties of single compounds.The heterostructure system which can reasonably utilize the energy of each band of solar energy is explored.It is hoped that the future energy industry will have a place for photo?electro/thermal?cataysis.In this thesis,the application of different heterstructures in photo?electro/thermal?cataysis was studied,and the following five parts were carried out:1.We synthesized the crystalline Cu₂O/amorphous Ta₂O₅ heterostructures using a multiple metal ions absorption and templating method.The experiment and calculation confirmed that the crystalline/amorphous contact could reduce the transport barrier for electrons,thereby separating the photo-generated electrons and holes to react with water.Therefore,it showed that the crystalline/amorphous contact had a great potential on realizing the high efficiency visible-light-driven overall water splitting on heterostructures.2.Tantalum?oxy?nitrides are in good band alignment coupling with TiO₂,However,the synthesis of tantalum oxynitride that requires high temperature nitridation?>800°C?limits the combination with other materials.Here,we develop amorphous TaO_xN_y modified TiO₂ heterostructure under lower temperature with high stability and boosting hydrogen generation rate.3.Fe₂TiO₅ is a promising photocatalyst.Nevertheless,the photocatalytic activity of pure Fe₂TiO₅ is relatively low and requires to be further modified because the growth of Fe₂TiO₅ is achieved by annealing the TiO₂/Fe₂O₃ composite,where a solid-state reaction between Fe₂O₃ and TiO₂ occurred at high temperature and nanostructure can not be well maintained.In this work,we have fabricated Fe₂TiO₅/TiO₂ heterostructures via templating and ion adsorption process and realize not only the small grain size,ultrahigh surface area,excellent crystalline compatibility and single-layer distribution but also the better band alignment of Fe₂TiO₅ and TiO₂.4.Efficient Ta₃N₅ photoanode was fabricated on Ta foil by direct oxidation and nitridation method with LaCl₃ flux mediated treatment.We achieved the highest photoresponse for Ta₃N₅ prepared by direct oxidation and nitridation of Ta foil.Theoretical analysis suggests an interfacial charge transfer from LaTaON₂ to Ta₃N₅ and significant increase in carrier concentration on La doped Ta₃N₅ surface.It can potentially be applied to large area and low cost photoanodes.5.We present a Fe₃Si assisted Co₃O₄ nanorods photothermal system for this purpose,with a good solar spectrum absorption,high photothermal conversion efficiency,low cost and achieve complete CO oxidation under 0.3-0.35 kW m^-2?¹/3Sun?solar irradiation outdoors.The CO conversion rate was stable outdoors during the test in a cloudy day,suggesting the practicality of Fe₃Si/Co₃O₄ photothermal system.