Preparation Of PtCu Nanostrands And Their Application In Non-enzymatic Glucose Sensor

The enzymatic sensor is easily affected by the environmental conditions, which leads to the disadvantages of insufficient long-term stability and unsatisfactory reproducibility. And this remains as problems for real sensor applications. However, with direct electrocatalytic oxidation of glucose at an enzyme-free electrode, the non-enzymatic sensor would exhibit advantages to avoid the disadvantages of the enzymatic electrode. Therefore, enzyme-free glucose sensor provides a promising approach for detection of glucose.Nanomaterials have attracted considerable attention due to their large surface area and great efficiency of catalysis. Among them, the noble metals are becoming the promising approaches. For instance, the noble nanomaterials are widely used to fabricate the non-enzymatic glucose sensor, with the sensitivity, detection limit and the range of response improved. In this article, we prepared bimetallic PtxCu1-x nanostrands through a facile and effective wet chemical strategy and employed them as electrode material for non-enzymatic glucose sensors. The morphologies of PtCu nanostrands were characterized by field emission scanning electron microscope (SEM). Surface elemental composition of the synthesized samples was characterized by an energy dispersive X-ray spectrometer (EDS). The microstructures of PtCu nanostrands were performed by high-resolution transmission electron microscope (HRTEM) and selected area electron diffraction (SAED). The powder X-ray diffractometer patterns were obtained using a X-ray diffractometer instrument (XRD). The effects of different experimental conditions on the morphology of PtCu nanocomposites were discussed. When PtCu nanostrands were used for detecting the glucose, the best catalytic properties and optimal potential could be obtained by study nanostrands with different compositions and potentials. The main results as follows:(1) The amount of NaBH4 has a great influence on the synthesis of nanostrands, high or low concentrations of NaBH4 are not conducive to the formation of good nanostrands. When the concentration of NaBH4 was 8 mmol·dm-3. the morphology of PtCu nanostrands could be the best.(2) The morphology and composition of PtCu nanostrands are significantly affected by the concentration of metal ions in the solution. It is not conducive to form high-quality PtCu nanostrands, with the concentration of Cu2+ being too low or too high. According to experiments, with PtCl62-:Cu2+ being 5:1, it can get the best shape of nanostrands.(3) The reaction temperature also has some influences on the formation of PtCu nanostrands. With too low or high temperature, the growth of the metal will not be well. When the reaction temperature is 60?, the prepared the PtCu nanostrands have the best morphology.(4) In this experiment, the morphology of the PtCu nanostrands can be optimited by different kinds of surfactants. Triton X-100 apparently primes to PVP, this may be explained that PVP is a strong capture agent, which is not beneficial to the formation of high-quality nanostrands. In addition, the amount of Triton X-100 also affects the morphology of nanostrands, with increasing amounts, better morphology is obtained. But it has an optimum dosage with 1-2 mmol·dm-3.(5) In order to evaluate the electrochemical behaviors of the PtCu nanostrands with different compositions, their electroactive surface areas are estimated by counting the surface sites for hydrogen adsorption using cyclic voltammetry. The result implies that the electroactive surface area of Pt7oCu30 nanostrands is the largest. According to the electrochemical impedance pectroscopy, the PtxCu1-xGCE electrodes were more conductive for electron transfer than the Pt electrode. Furthermore, the Rct of Pt70Cu30 is smallest, which is consistent with the results deduced from ESCA.(6) The electrochemical activities of the PtCu nanostrands with different compositions for electrochemical oxidation of glucose are investigated using cyclic voltammetry. Compared to the Pt nanostrands, it can be observed that the Pt70Cu30 modified electrode shows the best electrocatalytic activity toward the electrochemical oxidation of glucose. This is mainly due to the synergies between different atoms in the alloy.(7) To obtain the optimized potential, we have investigated the effect of detection potential on the amperometric responses of Pt70Cu30GCE electrode to different concentrations of glucose. The result implies that the optimized potential is 0.15 V. The current response of the sensor shows a linear dependence on glucose concentration (R2-0.99865) in the range of 0.1 to 19 mmol·dm-3 with the sensitivity of 23?A·dm-3mmol-1·cm-2 and a detection limit of 25 ?mol·dm-3 based on a signal to noise ratio of 3.(8) According to the amperometric response of the Pt70Cu30GCE electrode associated with the successive addition of different interfering species, it is observed that the response signals of ascorbic acid, acetamidophenol, uric acid and fructose are negligible for glucose determination, which reveals the good anti-interference ability of the Pt7oCu3oGCE electrode.(9) The non-enzymatic glucose sensor based on bimetallic Pt70Cu30 nanostrands electrode showed good reproducibility, repeatability and stability. And these excellent properties of the proposed sensor make it a promising candidate for glucose detection in blood sample.