The Styudy Of Electrochemilumine Of Coreactant-Bonded Quantum Dots

As a new type of fluorescent semiconductor nanomaterial,quantum dots?QDs?possess similar photoluminescence performances compared with the traditional luminophores such as Ru?bpy?₃²⁺.At the same time,they have good photostability and biocompatibility.Therefore,they have been widely used in environmental analysis,immunosensing,bioimaging and other fields.However,there are some challenges in the preparation and application of QDs,especially its ECL application.Firstly,the ECL efficiency of QDs is far less than the traditional ECL luminophores,which will limit the ECL of QDs for better applications.Secondly,QDs with ECL properties are mostly focused on cadmium-based semiconductors at present.Therefore,it is very significant to develop a green and efficient strategy to prepare novel QDs with low-toxic and ECL performance.In this paper,we synthesize novel self-electrochemiluminescent?self-ECL?nanomaterials by three different methods and explore their unique optical and electrochemical properties,thereby improving the ECL efficiency of QDs and eliminating additional coreactants in solution.This will be a huge potential for biosensing of QDs-based ECL.The main contents of the paper consist of the following three parts,which are summarized as follows:1.Novel2-diethylaminoethanethiol?DEAET?-protectedCdTenanocrystals?CdTe-DEAET NCs?were successfully synthesized by exchanging DEAET onto3-mercaptopropionic acid?MPA?-capped CdTe NCs?CdTe-MPA NCs?for the first time.Next,the optical and electrochemical properties of the materials are investigated before and after exchanging ligand.And the proposed ECL mechanism of CdTe-DEAET NCs was also studied.The results demonstrate that noticeable blue-shifts on the UV-vis absorption and photoluminescence spectra and the decrease of particle sizes are observed after ligand exchange.These differences may be attributed to the dissolution of the crystals.Simultaneously,a strong anodic ECL emission from CdTe-DEAET NCs is detected due to that DEAET assembled on the surface of NCs to act as a co-reactant for the ECL generation of CdTe NCs.In addition,ECL generation from CdTe-DEAET NCs is an intra-NCs reaction in contrast to conventional ECL pathways,which will be beneficial to impove ECL efficiency of NCs.2.A novel self-electrochemiluminescent?self-ECL?nanomaterial,CdTe quantum dots,is prepared by the one-pot method using 2-diethylaminoethanethiol?DEAET?as capping agent and co-reactant?CdTe@DEAET QDs?.Effects of various experimental variables such as Cd-to-Te ratio,pH value,and DEAET-to-Cd ratio on the optical and electrochemical properties have been systematically investigated.The results indicate that the as-prepared CdTe QDs show excellent size-dependent optical and self-ECL properties under optimal conditions.These results corroborate that this preparation method of QDs presents a simple and easily up-scalable method for large-scale production.3.CdTe-MPA-DEDA QDs with good self-ECL were synthesized by covalently attaching co-reactant N,N-diethylethylenediamine?DEDA?onto the prepared CdTe-MPA QDs via amidation reaction.Their optical properties,ECL behavior and mechanism are also studied in detail.ECL signal of CdTe-MPA-DEDA QDs prepared by amidation is significantly enhanced compared with the materials prepared by the former two methods,which has a great potential for ECL application in the future.