The Construction Of Photoelectrochemical Sensor And The Study Of Photoelectrocatalytic Water Oxidation Based On α-Fe₂O₃ Photoanode

Combining the characteristics of photocatalysis with photon driven and electrocatalysis with controllable potential,photoelectrocatalysis（PEC）has been widely investigated in the fields of solar fuel production,environmental remediation and sensors.Hematite（Fe₂O₃,αphase）is a highly promising photoanode material with the advantages of nontoxic,stable,abundant,significant light absorption（2.1 e V of band gap）and theory solar energy conversion efficiency of 15%.However,the application ofα-Fe₂O₃faces the challenges of poor charge transport,high recombination and low practical solar energy conversion efficiency due to the intrinsic properties of low carrier concentration,short charge life and short hole diffusion length.In view of these urgent,we prepareα-Fe₂O₃with one dimensional nanorods structure to narrow the bulk charge transfer distance,and modifies the Fe₂O₃surface with co-catalysts or functional layers to accelerate charge transport and charge injection,so as to promote the performance of Fe₂O₃-based photoelectrochemical devices and water oxidation.The detailed research is as follows.The unique separated energy forms of light excitation and electrochemical detection of PEC sensors make the analysis has lower detection noise and potential high sensitivity,which holds bright promise in the future applications.In this thesis,a Fe₂O₃photoanode based PEC sensor has constructed and shows excellent performance in glucose detection for the concentrations in the range of 0.2～2.0 m M with a linear correlation coefficient of0.997 and a sensitivity of 100.46μA cm^-2m M^-1.Furthermore,the fabricated sensor also displays good selectivity of glucose toward common interferents and excellent stability3for glucose sensing.Self-powered sensors have great application prospects in the field of analytic chemistry because they can determine analytes without inputting external electricity.In this work,we fabricate a photocatalytic fuel cell（PFC）device by using Ni（OH）₂/Fe₂O₃NR as photoanode.The devise not only generates electricity by converting solar energy but also successfully functions as a self-powered glucose sensor for glucose detection without supplying external electricicity.Under illumination,the generated maximum power density(P_max)shows a linear response to the glucose concentration from0.5 m M to 2.5 m M with a sensitivity of 24.59μW cm^-2m M^-1which is 7 folds of bared Fe₂O₃NR based PFC.The remarkable enhancement of Ni（OH）₂/Fe₂O₃NR PFC on power producing and glucose sensing is mainly attributed to the factors that Ni（OH）₂can improve photo-generated charge inject efficiency(η_inj)and it has high electrocatalytic activity for glucose oxidation.The Co-MOFs/PVP-Fe₂O₃composite is prepared by in-situ growth of cobalt metal-organic frameworks（Co-MOFs）on a polyvinylpyrrolidone（PVP）molecules modified Fe₂O₃photoanode via a hydrothermal process.The photocurrents of Co-MOFs/PVP-Fe₂O₃for water oxidation at 1.23 V vs.RHE are 1.9 and 5.3 folds of bared Fe₂O₃photoanode performance tested in alkaline and neutral electrolyte,respectively.Besides,the Co-MOFs/PVP-Fe₂O₃presents excellent stability for photoelectrochemical water oxidation.Furthermore,the characterizations of Mott-Schottky,photoluminescence spectrum and electrochemical impedance spectroscopy are employed to illustrate the intrinsic reasons for the superior water oxidation performance obtained on Co-MOFs/PVP-Fe₂O₃.The results indicate that the enhancement is because the existence of Co-MOFs increases the photo-generated electron density,reduces the recombination of charges and decreases the charge transfer resistance at the interface of electrode/solution.