Flexible Electrode Based On Bimetal PtM Nanocatalysts Decorated 3D Nanoporous Gold/Graphene Paper For Glucose Sensing

Diabetes is a metabolic disease characterized by high blood sugar, mainly resulting from insufficient insulin secretion. With the ever-increase of incidence of the diabetes year by year, the development of real-time rapid detection of blood sugar is of significant importance. Electrochemical sensors hold great promise in analytical chemistry and clinical medicine because of its a collection of advantages, such as high sensitivity, good selectivity,quick response, good stability, simple operation and easy to realize automatic continuous detection. In comparison to electrochemical enzymatic glucose sensors based on glucose oxidase(GOD), the nonenzymatic glucose sensors based on Pt electrode possess high stability, good anti-inference ability, simple manufacture, and low cost. However, the glucose oxidation reaction on Pt electrode is a sluggish kinetic-controlled process, which hinder the development and commercialization of nonenzymatic glucose sensors. In recently, in virtue of the innovation of nanotechnology, various novel functional nanomaterials have been developed. Nanomaterials reveal the unique electronic, optical, magnetic, mechanical and catalytic properties due to its good biocompatibility, high catalytic activity, large specific surface area and small size, and therefore exhibit great application prospect in electronics,sensors, catalysis. Especially, the bimetal Pt-based nanomaterials, possess high catalytic activity and anti-poisoning ability, which can dramatically improve the key parameters of the resultant sensors including sensitivity, selectivity and so on. The development of high-efficient strategies to increase the catalytic activity of the bimetal Pt-based nanomaterials and practicability of the resultant sensor have become research focuses in recent yearsIn this work, the free-standing nanoporous gold(NPG) and graphene paper(GP) were considered as a carrier loading bimetal Pt-based alloy nanoparticles to construct the new type of Pt-based noble metal PtPd/NPG@GP and Pt-based non-noble metal PtCo@NPG/GP flexible paper electrodes, which were applied to the direct electrocatalytic oxidation ofglucose. The main research content is as follows:(1) First, the NPG film with high porosity and specific surface area was prepared by dealloying Au50Ag50 alloy leaves, then the PtPd/NPG composite membrane based on platinum palladium nanoparticles modified NPG was further prepared through a simple chemical reduction method. Finally, PtPd/NPG composite film was transferred to the flexible GP electrode surface and got the new style of PtPd/NPG@GP flexible composite electrode.Scanning electron microscope(SEM) and Transmission electron microscope(TEM) images proved that the synthesized material retains the skeleton structure of the nanoporous gold and provides larger surface area and more nucleation sites for the growth of platinum palladium alloy. A series of electrochemical tests manifested that the resultant nanocomposites paper electrode has a good flexibility and certain mechanical strength. More importantly, the bending-induced mechanical stress is hardly affected on its catalytic activity.The sensor based on PtPd/NPG@GP paper electrode displays an excellent linearly responds to glucose up to 20 mM, with an outstanding detection limit of 50 ?M(S/N=3) and perfect sensitivity of 39.05 ?A·cm-2·mM-1. Meanwhile, the interference of electroactive materials of coexist in the physiological systems can be neglected relative to glucose, such as, ascorbic acid, uric acid and so on.(2) Based on the research of the previous chapter, platinum cobalt alloy nanoparticles with high catalytic activity was further growth in GP electrode surface modified with NPG( NPG/GP) by one-step in-situ electrodeposition method. The resulting composites is defined as PtCo@NPG/GP flexible paper electrode. SEM and X-ray photoelectron spectroscopy(XPS) characterization showed that the as-prepared PtCo alloy nanoparticles can uniform load in the surface of the NPG with a three-dimensional porous structure. This unique superstructure provides abundant electrochemical active sites for the oxidation of glucose, and accelerates the electron transfer between the electrode and analytes solution.Electrochemical tests indicated that the PtCo@NPG/GP electrode displays a higher electrocatalytic activity towards the oxidation of glucose compared to NPG/GP andPt@NPG/GP electrode prepared with a similar procedure, which attributed to the synergistic effect between matrix NPG/GP and the PtCo nanoparticles. Under the best conditions, the sensor response is linear to glucose concentrations in the range from 35 ?M to 30 m M, with a detection limit of 5 ?M(S/N=3) and sensitivity of 7.84 ?A·cm-2·mM-1. The recoveries of the spiked standard solutions are in the range from 95.2%~103.6%, with RSD values of1.56%~3.80% in the analysis of actual blood samples.