Study On The Analytical Methods For Sulfideions Assaybased On Silver And Palladium Nanoparticles

In recent years,noble metal nanoparticles have attracted extensive attention in the fields of catalysis,drug delivery,imaging,medical diagnosis and treatment,biological sensing,and environmental analysis owing to their unique optical and electrical properties.Based on the surface catalytic activity of noble metal nanoparticles,we herein successfully developed a new analytical method for the detection of sulfide ions in aqueous solution.This analytical method shows high sensitivity,selectivity and fast response for sulfide ions detection.In the experiment,we first prepared spherical silver nanoparticles(AgNPs)with uniform size(15 nm)and high monodispersity in aqueous solution through polyol method.It was found that the as-prepared AgNPs were able to accelerate the reaction rate for catalytic reduction of 4-nitrophenol.However,the reaction kinetics was slowed down when a series of different concentrations of sulfide ions were added into the system.Mechanism studies demonstrated that the result was owing to the surface poisoning of AgNPs,namely,the formation of a thin layer of Ag2 S on the surface of AgNPs.Based on the linear relationship between the rate constant and concentration of sulfide ions,the quantitative determination of sulfide in a range of0.5-7.5μmol/L is achieved.This method has been successfully applied in the determination of sulfide in real samples.Secondly,based on their high catalytic activity,Pd nanoparticles(PdNPs)with different shapes(cubic and octahedron)were further synthesized as analytical probes for the catalytic oxidation of3,3’,5,5’-tetramethylbenzidine(TMB)by H2O2.Based on this strategy,a highly sensitive method for the detection of sulfide ions was also established.In the experiment,we first used Pd cubes with edge length of 18 nm as a probe.The reaction is catalyzed at room temperature.When a series of different concentrations of sulfide ions were added to the system,the surface of Pd cubes was partially or completely poisoned via sulfuration,which inhibited the catalytic activity of Pd cubes and thus slowed down the reaction rate.Thus,a new method for sulfide ions assay was established through the quantitative relationship between the absorbance of TMB at 650 nm and the concentration of sulfideions.In addition,we also compared the catalytic activity of octahedrons Pd nanoparticles with cubes Pd nanoparticles,which might influence on the sensitivity of the analysis method due to the involved different crystal facets.In summary,the catalyst poisoning effect of noble metal nanoparticles is combined with analytical chemistry.Based on this strategy,simple,fast,highly sensitive and selective methods for the detection of sulfide ions in aqueous solution have been successfully developed.