| With the acceleration of the national modernization process,the contradiction between economic development and environmental protection has become increasingly serious.Among many environmental problems,the problem of water pollution has received wide attention.Especially,the pollution of inorganic heavy metal ions(HIMs)in aquatic environment can cause serious damage to the human’s body even its low concentration.However,water resource is necessary in our lives.Thus,trace detection of heavy metal ions in real aquatic environment is particularly important.In recent years,electrochemical sensors have attracted attention due to their high sensitivity,low cost,and simple operation.In addition,the constructed sensing interface plays an important role in the design of electrochemical sensors.Although many electrochemical sensors with high sensitivity have been reported,most reasons of high sensitivity are mainly attributed to the adsorption performance of constructed sensing interfaces.However,the study of electrochemical behavior for microscopic mechanism is still in the initial stage.Exploring microscopic mechanisms of electrochemical behavior is crucial to establish new sensing interfaces for the ultrasensitive determination of trace HIMs.Therefore,in consideration of exploring the microscopic mechanism,the structure-effect relationship between sensing interface and the electrochemical behavior is discussed by effect of oxygen vacancy.The work of this thesis mainly includes the following contents:(1)Ni-Mo binary oxides(Ni0.4Mo1.2O4)was prepared by a simple hydrothermal method and characterized by a series of characterizations.Here,Ni0.4Mo1.2O4 modified glass carbon electrode(GCE)[Ni0.4Mo1.2O4/GCE]has been realized the sensitive detection of Pb(Ⅱ),Cu(Ⅱ),Cd(Ⅱ),Hg(Ⅱ).And Ni0.4Mo1.2O4/GCE has the highest detection sensitivity for Pb(Ⅱ).Moreover,Ni0.4Mo1.2O4/GCE has good stability and reproducibility for the detection of Pb(Ⅱ).The high sensitivity of Pb(Ⅱ)is mainly ascribed to the presence of surface oxygen vacancy,which is beneficial to the capture of heavy metal ions.The preliminary exploration of this work also provided a study idea for the next work.(2)The doping content of Ce in α-MoO3 is regulated by hydrothermal method,thereby realizing the change of the physicochemical properties of the α-MoO3 nanostructure.In contrast of electrochemical detection results,we found that the sensitivity of C9M/GCE toward Pb(Ⅱ)can achieve at 106.64 μA μM-1 with a detection limit(LOD)of 0.015 uM.In order to explore the differences of electrochemical behavior during the testing process,adsorption test was carried out.The surrounding chemical environment of oxygen has been changed by XPS result after adsorption,which indicated oxygen element played a key role in the detection of Pb(II).Therefore,it is concluded that the presence of oxygen vacancies can promote to adsorb heavy metal ions,enhancing the sensitivity of electrochemical detection.In addition,we found that the different bond length of Pb-O is formed through four sensing interface in electrochemical behavior by X-ray absorption fine spectrum(XAFS)technology.Since the different bond lengths of Pb-O affect the diffusion rate from material surface to electrode surface leading to the different stripping signal. |
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