| Polyoxometalates are widely used in catalysis and electrochemical sensors owing to their excellent chemical stability,reversible redox activities,and special electrocatalytic properties.In this text,the Keggin-and Dawson-type molybdovanadophosphoric acid with other electroactive materials?eg.Ru?bpy?3,Cs-Pd,rGO?are used to build the composite film{PEI/[P2Mo17V/Ru?bpy?3/PSS/Cs-Pd]6/P2Mo17V}and{PEI/[PMo11V/PDDA-rGO]6/PMo11V}by the layer-by-layer self-assembly method for determination of ascorbic acid and nitrite.XPS,UV-vis,TEM,AFM,SEM were used to characterize the composition,and meanwhile,cyclic voltammetry,electrochemical impedance spectra and amperometry were used to investigate the electrochemical behavior and sensing properties of the composite films.The results indicated the two composite films modified electrochemical sensors had wider linear range,lower detection limit and fast response time.The composite film{PEI/[P2Mo17V/Ru?bpy?3/PSS/Cs-Pd]6/P2Mo17V}exhibited a wide linear range of 1.25×10-71.18×10-4 M,a low detection limit of 2.21×10-9 M?S/N=3?and fast response?<2 s?for sensing ascorbic acid.And the composite film{PEI/[PMo11V/PDDA-rGO]6/PMo11V}exhibited a wide linear range of 1.25×10-71.16×10-3 M,a low detection limit of2.8×10-9 M?S/N=3?and fast response?<2 s?for sensing nitrite.In addition,the two composite films exhibited good anti-interference ability towards common coexistent compounds at different applied potentials.Furthermore,the two composite films were employed to detect ascorbic acid and nitrite in the practical samples respectively and the recovery is acceptable within the allowed error range. |
PDF Full Text Request