Fabrication Of ZnO Quantum Dots Composite Films Based On The Electrodeposition Of Biopolymers And Their Application

Biopolymers have always been concerned by researchers owing to their good characteristics such as biocompatibility,renewability,extensive source and low cost.Electrodeposition technology of biopolymer enables biopolymers with responsiveness to external power signals to be electrically assembled on the electrode surface,and can realize the co-deposition of quantum dots,nanoparticles and other materials with biopolymers to obtain functional nanocomposites.In addition,ZnO quantum dots（ZnO QDs）are safe,non-toxic,easy to synthesis and possess unique optical and electronic properties,so that they are widely used in detection,light-emitting diode（LED）,biological imaging and other fields.In this study,the fabrication of ZnO QDs/biopolymers nanocomposite films based on the coordinated electrodeposition technology of biopolymers is carried out,and the application of nanocomposite films is studied.This work developed a method based on the coordinated electrodeposition of alginate to prepare ZnO QDs and fabricate ZnO QDs/alginate nanocomposite films.The resulting ZnO QDs/alginate nanocomposite film is homogeneous and smooth,and shows clear orange fluorescence under 365 nm UV light.ZnO QDs in the nanocomposite film have a typical hexagonal wurtzite crystal structure.The results of TEM show that ZnO QDs have a relatively uniform size and that the average size of those nanoparticles is 6.0 nm.Furthermore,the ZnO QDs/alginate nanocomposite film constructed on the electrode can be directly used for electrochemical applications,which has good electrochemical detection effect on K₃[Fe（CN）₆]and the limit of detection is 2.64μM.By taking advantage of the fluorescence properties of ZnO QDs,the ZnO QDs/alginate nanocomposite film can be applied to fluorescence detection of Cu²⁺ions.Therefore,the resulting ZnO QDs/sodium alginate nanocomposite film has promising applications in the fields of electrochemical and fluorescence detection.In this work,silica modified ZnO QDs with yellow emission was prepared by sol-gel method,which can be stable in aqueous solution.Compared with unmodified ZnO QDs,silica modified ZnO QDs show better fluorescence stability.XRD and TEM results indicate that silica modified ZnO QDs have a typical hexagonal wurtzite crystal structure.The chemical composition tests also prove the existence of ZnO QDs and silica.Moreover,the coordinated electrodeposition of carboxylated chitosan（CCS）with different metal plates was achieved based on the coordination between metal cations and CCS.The prepared Zn²⁺/CCS and Al³⁺/CCS gel film have obvious blue fluorescence under 365 nm UV light.The co-deposition of ZnO QDs and CCS was also realized by the coordinated electrodeposition technology of CCS in order to prepare nanocomposite films.When CCS solution mixed with different contents of ZnO QDs serves as the electrodeposition solution,the nanocomposite film prepared by electrodeposition may present polychromatic fluorescent,such as blue,white and yellow.In addition,the resulting nanocomposite film with white fluorescent can be potentially applied to the field of photoluminescence WLED.By changing the time and the type of anode metal of the co-deposition the fluorescent of the nanocomposite film can be regulated,so as to prepare nanocomposite film with desired fluorescent colors.According to the above results,this work realizes the preparation of nanocomposite films with patterned fluorescent.In summary,ZnO QDs/alginate nanocomposite films are prepared based on the electrodeposition technology of alginate,and it is found that the nanocomposite film has significant application value in the fields of electrochemical and fluorescence detection.The method has many advantages such as the simple operation,the mild condition and the environmentally friendly process,which provides a novel approach for the preparation of ZnO QDs and construction of its nanocomposite films.In addition,the co-deposition of yellow ZnO QDs and the blue fluorescent CCS gel film is accomplished through the coordinated electrodeposition of CCS,and the resulting nanocomposite film with polychromatic fluorescent can be applied to white LED.It is worth noting that the coordinated electrodeposition has good controllability,making the fluorescent colors of nanocomposite films can be regulated by changing the electrodeposition conditions,which provides a simple and controllable new method for the fabrication of polychromatic fluorescent materials.