Enzyme-free Electrochemical Sensor Based On Bimetal Nanomaterials

Bimetal alloy nanomaterial possess own excellent catalytic properties because of its catalytic activity of single metal and alloying of synergies.At the same time the right element of particle surface composition and atomic arrangement can improve the catalyst performance,reducing reaction by-products or sheet metal particle catalyst poisoning resistance.This paper synthesized mononuclear double shell Au@Ag@C nanocomposite,Au@C@Pt core-shell nano-material with the shape similar to popcorn and PtCu bimetal nanomaterials.These nanomaterisls were used to construct the enzyme-free sensor for the detection of hydrogen peroxide?H₂O₂?,dopamine?DA?and ethanol.?1?The well-designed Au@Ag@C core-double shell nanocomposites were synthesized via a facile method,and were used to fabricate an enzyme-free amperometric hydrogen peroxide?H₂O₂?biosensor.The size,shape,elementary composition and structure of the nanocomposites were characterized by transmission electron microscope?TEM?,energy-dispersed spectrum?EDS?and X-ray diffraction?XRD?.The outermost layer of the nanocomposites was amorphous carbon,the second layer was Ag and the core was Au.The Au@Ag@C core-double shell nanocomposites exhibit attractive activity for electrocatalytic reduction of H₂O₂according to the electrochemical experiments.The reduction peak current at 0.5 V increased with the increase of H₂O₂ concentration.It also demonstrates the H₂O₂biosensor possess well performance with a wide linear range of 5.0?M to 4.75 mM and a limit of detection?LOD?as low as 0.14?M.The good electrocatalytic activity of the Au@Ag@C is benefit from the synergy between three elements?C,Ag,Au?and the structure of core-shell and the nanometer size effect.Furthermore,the interference from the common interfering species such as glucose,ascorbic acid,dopamine and uric acid can be effectively avoided.?2?Gold?Au?,carbon?C?and platinum?Pt?are ideal choice to synthesize Au@C@Pt core-double shell nanocomposite,because of base materials owing to its unique electrochemical catalytic performance and good stability,convenient electron transfer and biocompatibility.The core-shell structure can make close contact between the Pt,C and Au.The well-designed Au@C@Pt core-double shell nanocomposites were characterized by SEM,TEM and EDS.The Pt-nanoclusters as the most outside layer were coat on the core-shell Au@C nanoparticles to construct core-double shell nanocomposites.The Au@C@Pt/GCE performs good electrocatalytic activity towards H₂O₂ with the catalytic potential at 0.0V,and can be used for the preparation of enzyme-free sensor to rapid and sensitive detect H₂O₂ and dopamine.Two wide linear ranges were obtained for H₂O₂.One is 9.0?M to 1.86 mM with sensitivity as high as 144.65?A mM^-11 cm^-2,the other is 1.86 mM to 7.11 mM with sensitivity of80.06?A mM^-11 cm^-2.When signal to noise?S/N?was 3,the detection limit?LOD?was 0.13?M and 55.93?M,respectively.The modified electrodes also have good electricalcatalytic to dopamine,and the DA detection range is 1.0?M to 0.35 mM.The modified electrodes with the detection of H₂O₂ and dopamine have high sensitivity and low detection limit,rapid response,good stability and high anti-interference ability.?3?We synthesized PtCu bimetallic nanomaterials and carbon quantum dots?CQDs?.The PtCu nanomaterials and CQDs were droped to glassy carbon electrode and we studied its electrocatalytic to ethanol.Bimetallic nanoparticles showed a new function of the synergy between the two kinds of metal.At the same time,CQDs have good biological intermiscibility and more active sites.Cyclic voltammetry experiments showed that the PtCu/CQDs can effectively promote the electron transfer and possess good electrocatalytic performance to ethanol,the linear range is 20³00mM and the detection limit is 3.83 mM.Chronoamperometry experiment showed that the modified electrodes can quickly respond to the change of the ethanol concentration,the steady state current reaches about 95%less than 20 s.The modified electrode also has good stability and reproducibility.