Study On Synthesis And Property Of CdS-based Photocatalyst Driven By Visible-light

Cadmium sulfide(CdS)is one of the most popular visible-light photocatalysts for hydrogen production for its wide-range light absorption,efficient photoexciton generation and appropriate photoredox potentials.Unfortunately,there are mainly two inferior issues that restrict nanoscale CdS photocatalyst to be extensively utilized.On one hand,pristine CdS usually exhibits low photocatalytic activities of hydrogen production due to the ultrafast photoexciton recombination and the lack of reactive sites.On the other hand,CdS photocatalyst has been suffering from the instability caused by the well-known photocorrison.The optimized modification of CdS is mainly through the combination with other co-catalysts.In substantial investigations,a lot of attention begins to be paid to the molybdenum sulphide(MoS2),which is composed of earth-abundant elements,for its desirable hydrogen evolution reactivity and low cost.Consequently,MoS2 has become one of the most promising materials to replace noble metal.Up to now,those reports of MoS2/CdS composites mainly focus on few-layer or single-layer MoS2 nanosheets approaching metallic properties,while multilayered MoS2 nanosheets with semiconductor nature are rarely considered.Normally,the multilayered MoS2 is an indirect band-gap n-type semiconductor which can composited with direct-band-gap CdS to form a type-I junction,which possesses inferior recombination rate of photo-generated holes and electrons and suspends the photocorrosion of CdS.Thus,this paper through fabricate CdS@MoS2 core-shell composites to further study of multilayered MoS2 as co-catalyst effect on photocatalytic performance and stability of CdS.However,multilayered MoS2 has the disadvantage of poor interlayer conductivity.We hope to improve the conductivity by construct oxygen-incorporated multilayered MoS2(O-MoS2).Therefore,we further investigate the effect of O-MoS2 on photocatalytic performance of CdS by fabricate the O-MoS2/CdS composites.The main research contents,innovations and achievements of this paper are as follows:(1)Constructing CdS@MoS2 composites by utilizing 1D CdS nanowires and multilayered MoS2 nanosheets to simultaneous realization of enhanced photoactivity and promoted photostability.Due to the unique core-shell structure,the multilayered MoS2 forms a type-I junction with the direct bandgap CdS and provides large amount of active sites,the hydrogen production rate of CdS@MoS2 is about 54 times greater than pure CdS and about twice of CdS-Pt.Impressively,the composites maintain stable hydrogen production rates in 12 hours.(2)Preparation of O-MoS2/CdS composites by appropriate feed regulation of C2H5NS.O-MoS2 can not only provide a large number of active sites,but also improve the conductivity of multilayered MoS2 which benefit the photo-generated electrons migration,improving the isolation of photo-induced electron-holes pairs.The composites exhibit excellent hydrogen production rate,which is about 35 times greater than pure CdS.Moreover,the photocatalytic performance of O-MoS2/CdS is better than CdS-Pt and MoS2/CdS composites,and composites maintain stable hydrogen production rates in 16 hours.