Preparation Of Poly(Thionine)/Go Photoelectrode And Its Application In Analytical Chemistry

The photoelectrochemical(PEC) analysis is a detecting method based on energytransformation from light to electricity. The two separating processes in the excitationand detection is aremarkable characteristic forPEC analytical method.In relation tophotochemical method, PEC method has the advantages of the simple equipment, lowcost, easy miniaturization and integration. It has higher sensitivity and goodselectivity compared with generally electrochemical method. In recent years, thestudies of photoelectrodeas sensitive deviceshave been rapidly developed in PECanalysis.The selectivity, sensitivity, response time and applicative range of PECanalysiscould be improved by chemical modification to various photoelectrodes.In the paper, the poly(thionine)/graphene oxide(GO)photoelectrode withphotoelectric activity and electron acceptor was prepared byelectropolymerizingthionine (Th) on the surface of GO-modified ITO electrode. Wefound that the prepared photoelectrode can produce PEC reaction withhydrogenperoxide (H2O2) as electron donor. Because H2O2is an intermediate ofenzyme-catalyzed reaction, the catalytic activity of protein and its substrate could bedetermined indirectly by measuring of photocurrent produced in the enzymaticreaction. On the basis of this principle, a PEC bionic interfacehas been fabricated foroxidizing H2O2.By combining the photoelectrode and controllable flowtechnique toimprove the accuracy and repeatability of determination, PECanalysis methods havebeen developed for rapid determination of H2O2andglucose.On the basis of thepreparation and applicationof photoelectrode, the studied work mainly is as follows:1. GO was successfullyobtained from natural flake graphite by Hummers method.GOcan be dispersein water toform a tanand uniformsolution, and retain stable for along time.SEM displayedGOhas wrinkled or distorted lamellar structure,and FT-IRanalysis showed many oxygen-contained groups on the surface of GO. XRD showedthatGO has a good crystal structure, and the interlayer spacing is estimated to be0.8nm,increased significantly compared to the natural flake graphite.2. Based on the characteristics of GO,the photoelectrode was prepared.Thephotoelectrode as photosensitive interface and an electron acceptor can simulate thefunction of catalase to catalyze the oxidation of H2O2,produced PEC reaction with H2O2. Thereby, H2O2can be detected by detecting the photocurrent. In the paper, theeffects of the bias voltage and the electrolyte pH on the photocurrent wereinvestigatedfor detecting H2O2, and PEC reaction mechanism was discussedonphotosensitive interface and H2O2. Experimental results show that, the photocurrentof Photoelectrode increased with the increasing of the concentration of H2O2. Thephotocurrentresponses displayed a linear increase as the concentration increased from5.00×10-7to1.00×10-4mol/L. The correlation coefficient is PI(nA)=73.0+5.863C(μmol/L)，and the relative standard deviation (RSD) is0.9978. The detection limit is5.0×10-8mol/L.The relative standard deviation (RSD) is less than3.18%for fiveparallel measurements of same sample.A novel PEC glucose sensor was prepared through the glucose oxidase wasimmobilized at the photoelectrodeby using the chitosan embeddedmethod. Under theoptimalconditions, the photocurrentresponses displayed a linear increase as theglucoseconcentration increased from5.00×10-7to1.00×10-4mol/L with adetectionlimit of5×10-7mol/L.The relative standard deviation (RSD) is less than6.78%forfive parallel measurements of same sample.