Abstract
In this paper, AuPt bimetallic nanoparticles-graphene nanocomposites were obtained by electrochemical co-reduction of graphene oxide (GO), HAuCl4 and H2PtCl6. The as-prepared AuPt bimetallic nanoparticles-graphene nanocomposites were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and other electrochemical methods. The morphology and composition of the nanocomposite could be easily controlled by adjusting the HAuCl4/H2PtCl6 concentration ratio. The electrochemical experiments showed that when the concentration ratio of HAuCl4/H2PtCl6 was 1:1, the obtained AuPt bimetallic nanoparticles-graphene nanocomposite (denoted as Au1Pt1NPs-GR) possessed the highest electrocatalytic activity toward dopamine (DA). As such, Au1Pt1NPs-GR nanocomposites were used to detect DA in the presence of ascorbic acid (AA) and uric acid (UA) using the differential pulse voltammetry (DPV) technique and on the modified electrode, there were three separate DPV oxidation peaks with the peak potential separations of 177 mV, 130 mV and 307 mV for DA and AA, DA and UA, AA and UA, respectively. The linear range of the constructed DA sensor was from 1.6 μM to 39.7 μM with a detection limit of 0.1 μM (S/N = 3). The obtained DA sensor with good stability, high reproducibility and excellent selectivity made it possible to detect DA in human urine samples.
Highlights
In recent years, bimetallic nanoparticles have gained significant research attention and have been widely applied in a variety of fields, such as electrochemical sensors [1,2,3,4,5,6,7], fuel cells [8,9,10,11,12], and raman scattering [13] due to their unique physical and chemical properties
All electrochemical measurements were performed on a CHI (Chenhua Instrument company, Shanghai, China) 650E electrochemical workstation with a three-electrode system consisting of a glassy carbon electrode, an Ag/AgCl reference electrode and a platinum wire auxiliary electrode. 0.1 M PBS was used as an electrolyte solution
It was obvious that the density of PtNPs was much lower than that of AuNPs, which indicated that the depositon of AuNPs on the surface of GR was much easier than that of PtNPs under the same electrochemical co-reduction conditions
Summary
Bimetallic nanoparticles have gained significant research attention and have been widely applied in a variety of fields, such as electrochemical sensors [1,2,3,4,5,6,7], fuel cells [8,9,10,11,12], and raman scattering [13] due to their unique physical and chemical properties. Well-known that direct electrochemical detection of DA at bare electrodes is nearly impossible, because interfering substances such as ascorbic acid (AA) and uric acid (UA) usually co-exist with DA in body fluids outside of cells at a high concentration level and can be oxidized within the same potential range as that of DA To address these problems, many composites, such as ion-exchange membranes [29], conducting polymer films [30,31], carbon nanotubes [32,33,34], metal and metal oxide nanoparticles [35,36,37,38,39,40], tyrosinase-based materials [41,42], have been used to enhance the selectivity and sensitivity of electrodes. The obtained DA sensor showed good selectivity and sensitivity toward DA, and the results of dopamine detection in human urine samples was satisfactory
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