Photoelectrochemical Sensor Based On Self Assembled Gold/Zinc Sulfide Composite Structure

In recent years, the photoelectrochemical detection method due to the advantages of high sensitivity, simple equipment, easy miniaturization and other advantages, such as chemical, pharmaceutical, food, environmental monitoring, biological, etc., it has become one of the most popular research topics in the present.Photoelectrochemical detection is based on the photoelectric chemically active substances, among the many optoelectronic active materials, inorganic semiconductor nano materials（quantum dots） are the most widely studied and also the most potential materials. But the photoelectric response of single quantum dot is not high, the current is not big, so we need to combine the quantum dots with other materials. Gold nanoparticles have high stability, good electrical conductivity, simple preparation method, and can produce synergistic effect with the combination of quantum dots, Therefore in this paper through will QDs and Au nanoparticles composite, accelerate the electron transfer rate, improve the separation efficiency of electron hole and photoelectric conversion efficiency, increase the photocurrent. The research of composite materials based on gold nanoparticles and quantum dots is more and more in the analysis of photoelectric chemical sensors.In this paper main contents include:1. Firstly, the water soluble TGA-ZnSQDs and AuNPs were synthesized, then, the ITO/Au/ ZnS modified electrode was prepared by electrostatic adsorption and self loading method, with PDDA as a crosslinking agent, and characterized by SEM, TEM, UV-vis, XRD, EIS etc.. The photoelectric properties of ITO/Au, ITO/ZnS, ITO/Au/ZnS and ITO/CdS electrodes are compared in the three electrode system. It shows that the Au NPs and ZnS QDs composite can increase the ZnS quantum dots of the electron hole separation rate, leading to the photocurrent increases. Finally, the experiment investigated the stability of ITO/Au/ZnS electrode, ITO/Au/ZnS electrode stability can continue to be made PEC sensor.2. The ITO/Au/ZnO electrodes are made of PEC sensors, and applied to the detection of Cu²⁺ ions. First of all, the photoelectric detecting conditions were optimized, then different concentrations of copper ions were detected under the optimal conditions. The experimental results show that the sensor has a super sensitive response to the low concentration Cu²⁺ ions. The linear range is 1 nM-1 μM, and the detection limit is 0.5nM（S/N=3）. By comparison with other Cu²⁺ ions PEC sensors, the sensor has higher sensitivity and lower detection limit. It was applied to the detection of the actual water samples, and compared with the results of ICP-MS, the results were satisfactory. At the same time, the ITO /Au/ ZnS sensor has an important significance in scientific research and environmental protection with low toxicity, environmentally friendly.