Research On Functionalized Nanomaterials Based Electrochemical Sensors For Organic Environmental Pollutants

Due to their simple operation,fast response and high sensitivity,electrochemical sensors are widely used in environmental detection,food detection and biological detection,etc.Modifying nanomaterials with unique physical and chemical properties to the electrode surface can improve and enhance the performance of electrochemical sensors.In this work,based on two-dimensional layered graphene oxide and molybdenum selenide?MoSe₂?,four functionalized nanocomposites were prepared by various methods and used for the construction of electrochemical sensors for organic environmental pollutants.The main contents carried out in this work were as follows:?1?A Ni-based metal-organic framework/graphene oxide?Ni-MOF/GO?composite was prepared by chemical precipitation method and fixed on a glassy carbon electrode?GCE?to prepare a modified electrode?Ni-MOF/GO/GCE?.The electrochemical behavior of4-chloronitrobenzene?4-CNB?on Ni-MOF/GO/GCE was studied by cyclic voltammetry and differential pulse voltammetry.The results showed that the selective determination of4-CNB was achieved by using Ni-MOF/GO/GCE.The response current of 4-CNB exhibited linear with its concentration in the range of 0.10³00?M.When the signal-to-noise ratio was 3?S/N=3?,the detection limit was calculated as 8.0 nM.?2?Phosphomolybdic acid(PMo₁₂)was immobilized on GO substrate by electrochemical deposition to prepare PMo₁₂/GO composite.The composite was further modified on the surface of GCE to obtain a modified electrode(PMo₁₂/GO/GCE).Cyclic voltammetry and differential pulse voltammetry were employed to study the electrochemical behavior of diphenylamine?DPA?on PMo₁₂/GO/GCE.Experimental results showed that as-prepared PMo₁₂/GO/GCE showed good electrocatalytic activity and selectivity for DPA.The response current of DPA was linearly related to its concentration in the range of 0.05⁴00?M,and the detection limit was calculated as 6.0 nM?S/N=3?.?3?Ni nanoparticle-modified nitrogen-doped GO?Ni/N-GO?composite was prepared by high temperature thermal reduction method and used to construct an electrochemical sensor?Ni/N-GO/GCE?.Cyclic voltammetry and differential pulse voltammetry were used to study the electrochemical properties of Ni/N-GO/GCE.The oxidation peak potentials of hydroquinone?HQ?and catechol?CC?on Ni/N-GO/GCE were 0.07 and 0.17 V,respectively.The peak potential separation of HQ-CC was 100 mV,which made the simultaneous determination of CC and HQ can be achieved.The concentrations of HQ and CC were in the ranges of 1.4⁸00 and 1.0⁸00?M,respectively,and the response currents and concentrations showed good linear relationships.The detection limits were calculated as0.06 and 0.16?M?S/N=3?,respectively.?4?A rare earth element Ce-doped MoSe₂ two-dimensional nanomaterial?CeMoSe₂?was prepred by hydrothermal method and used to prepare a modified electrode?CeMoSe₂/GCE?.Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of 4-nitrophenol?4-NP?on CeMoSe₂/GCE.The results showed that CeMoSe₂/GCE was used for the selective determination of 4-NP.The response current of 4-NP showed a good linear relationship with concentration in the range of 0.10¹20?M.The detection limit was calculated as 0.056?M?S/N=3?.In summary,four kinds of functional nanomaterials:Ni-MOF/GO,PMo₁₂/GO,Ni/N-GO and CeMoSe₂ were prepared in the study and used to construct electrochemical sensors for environmental pollutants.The results showed that the four resulting modified electrodes exhibited high electrocatalytic activity and selectivity for the object analytes.