Preparation Of Tin Disulfide Nanomaterials And Their Photocatalytic Properties

The conversion of solar energy into chemical energy or organic fuel through photocatalytic reactions is considered as an effective way to solve the energy and environmental crisis.With deepening understanding of photocatalytic reactions,various photocatalysts have been developed to achieve highly efficient photocatalytic activity.Compared with traditional Ti O₂oxide photocatalysts,tin-based two-dimensional metal sulfides can respond to visible light and have a high carrier mobility,which is considered to be a very promising visible light photocatalyst.However,the high carrier recombination efficiency severely limits its application in the field of photocatalysis.To solve the above problems,we designed modified tin disulfide nanosheets with high photocatalytic activity from the perspective of material preparation.The research results obtained are as follows:?1?SnS₂ nanocrystals with high specific surface area and few layers with different S vacancy concentrations were first prepared by low-temperature solid-state method to improve carrier separation and transport capabilities,and achieve efficient photocatalytic Cr???reduction performance.The introduction of S vacancies is equivalent to N-type doping,which improves the carrier transport efficiency of the material.The role of thiourea in the reaction act as a capping agent which limits the growth of SnS₂ in the layer direction,and then shortens the distance of carrier migration.The high-concentration sulfur vacancy SnS₂ has higher specific surface area and light absorption efficiency than the low-concentration SnS₂,and the photocatalytic Cr???reduction efficiency is increased about 2.5 times,and it exhibits excellent light response ability and carrier separation efficiency.?2?The"top-down"preparation method uses K₂Sn₂S₈ as a precursor to prepare Ag⁺surface-modified exfoliated SnS₂ nanosheets by acid exchange,which increases the catalytic active sites on the surface of the material and achieves excellent methyl orange degradation ability.Compound K₂Sn₂S₈ crystal structure consists of sulfur-rich[SnS₄?S₄?]^2-anion skeleton and interlayer K⁺.During the acid exchange process,K⁺ions are released from the structure,and then the sulfur-rich anion skeleton is restructured.There are many dangling bonds on the surface of the obtained SnS₂ nanosheets,which is beneficial to the subsequent modification of Ag⁺ions.Ag⁺modified samples have broadened light absorption range,and the degradation efficiency of Ag-SnS₂-2 methyl orange is increased by three times compared to the intrinsic material.