Photoluminescence Properties And Photocatalytic Applications Of Zn-doped CuInSe Quantum Dots

Sustainable development is the only feasible way to support the develop of human society and economy.However,both environmental pollution and resource exhaustion are two main obstacles for such a promising development.Photocatalytic technology has brought about new hope to solve these obstacles.CuInSe₂ quantum dots are widely used in life science,solar cell,and environmental management due to their unique optical properties,and low toxicity.Through incorporating extrinsic elements to control the optical properties is one of the main research interests.Here,Zn doping CuInSe₂ quantum dots?ZCISe?and core-shell ZCISe/ZnS quantum dots weresuccessfullypreparedandcharacterization.Then,highefficiency photoelectrodes of Mn-CdS/ZCISe/ZnO nanosheets and ZCISe/MoS₂/TiO₂ nanowire composites were constructed for photocatalytic application.The main research contents are shown as follows:?1?The ZCISe and ZCISe/ZnS quantum dots were prepared by a hot injection method.The spectral tunability of ZCISe quantum dots was realized by changing the Zn content to control the Cu/Zn ratio.Then,ZCISe is used as the core for an outmost layer ZnS shell growth.The ZnS shell content was controlled by adjusting In/Zn ratio and reaction time.The Zn content-dependent optical property of ZCISe quantum dots,and shell content-dependent optical property of ZCISe/ZnS quantum dots were studied.The energy levels of band gap and defects of quantum dots was also evaluated with the cyclic voltammetry.?2?Preparation of Mn-CdS and ZCISe quantum dot sensitized ZnO nanosheets andapplicationofazodyedegradation.Theglutathione?GSH?and mercaptopropionic acid?MPA?modified internal defect-rich,surface defects-poor near infrared?NIR?Zn–CuInSe₂?ZCISe?QDs were synthesized.Nanoporous ZnO nanosheets?NS?were firstly loaded with those ZCISe QDs to improve photoelectrochemical response in the NIR light region.Then loading Mn doping CdS thin film onto the ZCISe/ZnO NS was further used to reduce the interfacial recombination between different components of hybrid photoelectrode,in addition to enhance the light absorption and resist the photo-oxidation decomposition of the photocatalysts.Successively introducing ZCISe and Mn–CdS onto ZnO NS can increase the photocurrent intensities from 1 mA/cm²for naked ZnO NS,2.2 mA/cm²for ZCISe/ZnO NS,to 9 mA/cm²for Mn–CdS/ZCISe/ZnO NS.Here,excellent performance of ZCISe based ZnO NS photoelectrode is mainly attributed to an intrinsic defect state-related donor–acceptor pair?DAP?in ZCISe QDs with long-lived photogenerated carriers.Photocatalytic properties of Mn–CdS/ZCISe/ZnO NS were evaluated by removing azo dyes with an efficiency of 83%,an enhancement of 97%compared to that of ZnO NS.?3?Due to the presence of potential toxicity heavy metal element Cd in Mn-CdS/ZCISe/ZnO NS composite electrode,which is easy to cause secondary pollution,and the stability of ZnO nanosheets in strong acid and alkali solution needs to be improved.Thus,in this chapter,MoS₂ and TiO₂ are used to replace CdS and ZnO to study photocatalysis.As an useful strategy,defect engineering is often used for structural design to produce desirable defect-rich crystal planes through defects induced crystal cracking process,which successfully promotes the defined and fragmented growth of MoS₂ crystal lattice,and MoS₂ grow on the beforehand placed TiO₂ NW/Ti electrode in a high pressure with teflon-lined stainless steel autoclave.MoS₂ anchored TiO₂ NW/Ti can be easily obtained through precious precursors concentration control.The post-annealing treatment of MoS₂/TiO₂ NW/Ti not only curve the crystal plane of MoS₂ but also influence the electrode's photocatalytic onset potential and catalytic current density.Finally,a hybrid photocatalytic electrode was prepared to evaluate the application potential in combination of the excellent electrocatalytic performance from MoS₂ nanomaterials and photoelectric conversion performance from near-infrared Zn doped CuInSe QDs.The hybrid electrodes display good performance for removal of Cr?VI?.