Structural Design And Performance Research Based On Layered Metal Sulfides Photocatalysts

To overcome the global energy crisis and environmental pollution,it is an efficient strategy to develop the visible-light-driven semiconductor photocatalyst.Among many semiconductors,the layered metal sulfides are very suitable catalyst materials for visible light driven photocatalysts due to their narrow band gap and high charge mobility.Here,the layered metal sulfides of MoS₂ and SnS₂ were representatively selected to develop efficient photocatalyst through tunable morphology and construction of heterojunction.The main contents include the following aspects:?1?The 3D flower-like MoS₂ hemispheres assembled by many MoS₂ nano-sheet petals were synthesized by hydrothermal method,which possessed the wide spectral absorption ability in visible range.The effects of the morphology of photocatalyst and initial pH value of the solution on the performance of the photocatalyst were investigated.In order to further improve the photocatalytic efficiency of MoS₂-based photocatalyst,the MoS₂/g-C₃N₄ heterojunction photocatalyst was prepared.The properties of spectral absorption capacity,carrier separation and transfer efficiency on photocatalytic efficiency were also systematically investigated.The detailed charge transfer mechanism was discussed by combining theoretical calculation and experiments.?2?SnS₂ is a very promising photocatalyst due to its high crystallinity and electron mobility.Here,the different exposed crystal facets of SnS₂ photocatalysts were prepared by nanomorphological regulation.Their spectral absorption properties and photocatalytic properties were investigated,in which the exposed?001?crystal facet of SnS₂ is most favorable for the improvement of its photocatalytic performance as result of the enhanced spectral absorption capacity.Furthermore,3D flower-like SnS₂/Cu₂S heterojunction photocatalyst with more?001?crystal facet of SnS₂ was synthesized by one-step hydrothermal method.The spectral absorption ability of SnS₂/Cu₂S is greatly enhanced in the visible light region due to the addition of the appropriate amount of Cu₂S nanodots,which is the important factor for the improvement of its photocatalytic performance.?3?The ideal photocatalyst not only offers high photo-generated electron hole separation ability,but also simultaneously has suitable redox potential.Herein,a direct Z-scheme core-shell structured WO₃@SnS₂ hetero-junction photo-catalyst was prepared via two-step hydrothermal method,in which the mechanism of charge transfer of the WO₃@SnS₂heterojunction were discussed through the combination of theoretical calculation and experimental characterizations.The photocatalytic performance of the unique heterostructure were greatly improved due to the enhanced spectral absorotion capacity and the promoted separation of photogenerated electron-hole pairs while maintaining its optimal redox capacity.