Preparation Of Metal Sulphide Nanocomposite Photocatalysts And Their Performance

Solar energy is a widely obtained,clean,non-polluting and inexhaustible natural resource,and it has long been considered one of the most promising sustainable energy sources.The solar energy can be effectively converted to chemical energy stored in the form of hydrogen over semiconductor by photocatalysis.Therefore photocatalysis is regarded to be a highly desirable solution to overcome the problem of high power loss of the solar electricity and long-term energy needs by photovoltaics.Thus the design and modification of semiconductors can exploit sunlight active catalysts.Hence,the present paper focuses on the research of controlled synthesis and morphology adjustment of metal sulfide nanomaterials(cadmium,zinc sulfide).Besides,the efficiently improved photocatalytic activity is achieved by introduction of low-cost cocatalyst.In the second chapter,two kinds of morphology of hollow CdS particles were prepared by a two-step ion exchange where AgBr and AgCl worked as a template,respectively.In comparison,because of the smaller size,the hollow CdS nanoplates(P-CdS)exhibited higher photocatalytic activity with a rate of 0.332 mmol·gcat-1·h-1 H2 evolution.On this basis,the photocatalytic activity can be further improved by in-situ deposition of Pt nanoparticles on hollow CdS structure.Finally,it showed a hydrogen evolution of 3.75 mmol·gcat-1·h-1 over the P-CdS/Pt composite and the catalyst still remain active in continuous solar illuminance for 16 days.Unfortunately,the above noble-metal cocatalysts are too scarce and expensive to be used for large-scale application.Therefore,the development of noble-metal free cocatalysts with high efficiency and low cost is highly desirable.In the third chapter,layered MoS2 and low cost Ni(Co)S nanoparticles were utilized to be coated on the multi-armed CdS nanorods in order to replace the noble Pt.The result of photocatalytic performance confirmed that a contact interface is formed with MoS2/Ni(Co)S and multi-armed CdS nanorods,which efficiently improve charge transport,thereby improving photocatalytic properties.In comparison with Pt nanoparticles,the CdS coated by MoS2/Ni(Co)S exhibited higher photocatalytic activity with a rate of 9.187 mmol·gcat-1·h-1 for hydrogen production than that loaded with Pt nanoparticles.It is found that ZnCdS solid solution shows higher photocatalytic activity than CdS,thereby to further improve the photocatalytic efficiency the content of Chapter four is to explore the synthesis and application of ZnCdS nanorods used as main catalyst and two-dimensional MoS2/NiS used as dual co-catalyst.Instead of the multi-step hydrothermal synthesis used in Chapter three,a one-pot method were firstly employed for simultaneous preparation of ZnCdS/MoS2 1D/2D composites,and then NiS nanoparticles were loaded end up ZnCdS/MoS2/NiS composite catalyst.The excellently structural properties of combination of two-dimensional MoS2 and one-dimensional ZnCdS nanorods improve the utilization of charges.That is,MoS2/NiS played a synergistic effect during photocatalytic hydrogen production process.Extraordinarily,the best rate of photocatalytic hydrogen production over this system is up to 41.29 mmol·gcat-1·h-1 with a good cycle stability.