| Semiconductors have attracted intensive attention and been applied widely in the cutting-edge interdisciplinary science such as chemistry,physics,materials,and the environment science due to its unique optical and electrical properties.In recent years,people pay more and more attentions to the potential of semiconductors acting as photoelectrocatalysts and materials for photoluminescence because energy crisis and environmental issues.This thesis focuses on two types of semiconductor of CdS and inorganic perovskite,respectively.The following mainly contents are included:photoelectrocatalytic performance of CdS nanorods in electrolyte containing hydrazine as sacrificial agent;design and preparation of Bi2S3/CdS nanosheet arrays and their photoelectrocatalytic performance;circularly polarized luminescence(CPL)originates from chiral transfer through the co-assembly of inorganic perovskite nanocrystals and chiral molecules.The main findings are as follows:(1)The stability of CdS based photoanode was enhanced up to over 100 hours in the presence of a special sacrificial agent.CdS nanorod was synthesized by hydrothermal method and the obtained sample was used as the photoanode materials.It was explored that the stability of the system was improved by adding hydrazine as a sacrificial agent to the electrolyte.The results show that the photocurrent density of CdS nanorod reaches up to 7.6 mA cm-2 in the electrolyte containing sacrificial agent at bias potentials 1.23 V vs.RHE,which is more than five times as that of CdS in electrolyte without hydrazine.The photocurrent density of CdS nanorods was very stable and more than 82%of the initial photocurrent density was still sustained after continuous 100 h illumination at bias potentials 1.23 V vs.RHE.Besides,the structural morphology of CdS nanorods remained basically unchanged after long time illumination,which shows that the addition of sacrificial agent is an effective way to separate and transport charge carrier pairs and leads to superior photoelectrocatalytic performance and stability for CdS photoanode.(2)A novel photoelectrode based on Bi2S3/CdS nanosheet arrays was designed and prepared.Bi2S3/CdS nanosheet arrays were prepared by electrodeposition,ion exchange and hydrothermal processes,respectively.The obtained samples were used as a photoelectrode and the properties were analyed in detail by SEM,XPS,TEM,IPCE and photoelectrochemical measurements,respectively.The results show that the photocurrent density of Bi2S3/CdS nanosheets reaches 9.48 mA cm-2 in the Na2SO3 electrolyte at basis potentials 1.23 V vs.RHE,which is much higher than that of Bi2S3 or CdS.At the same time,the photoelectrode exhibited good stability against photo corrosion.More than 70%of the initial photocurrent density of Bi2S3/CdS nanosheets was still sustained after continuous 4 h illumination.In addition,the reaction mechanism of photoelectrochemical water spilling was proposed based on the date of electrochemical impedance spectroscopy,Motte-Schottky curves and so on.(3)Perovskite nanocrystals with circularly polarized luminescence were achieved for the first time through co-assembly of achiral nanocrystals and chiral gelators.Luminescent perovskite nanocrystals with various color and high quantum yield were prepared by ultrasonic synthesis.Circularly polarized luminescence(CPL)from achiral perovskite nanocrystals was achieved by co-assembly of the obtained nanocrystals and chiral gelators due to the chirality transfer from chiral organic molecules to achiral inorganic nanocrystals.The results showed that the quantum yield is as high as 93%and the asymmetry factor for CPL reached 7.3×10-3 in the co-assembly system.In addition,the fluorescent lifetime of perovskite nanocrystals in the co-assembly system is higher than that of pure nanocrystals,indicating that the non-radiative transition of nanocrystals was suppressed.Finally,based on the results of the experiments,the mechanism of CPL from achiral perovskite nanocrystals was proposed. |
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