Au Nanostructures on Flexible Substrate: Fabrication and Applications in Biosensor and Supercapacito

• Main Authors: Chen, Yu-Liang, 陳昱良
• Other Authors: Chiu, Hsin-Tien
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/99674687789499474579

博士 === 國立交通大學 === 應用化學系碩博士班 === 102 === In this thesis, we studied fabrication of Au nanostructures on flexible substrate and its applications in biosensor and supercapacitor. A facile fabrication of high density Au nanostructures including nanothorns (NTs), nanocorals (NCs), nanoslices (NSs), and nanowires (NWs) which were electrochemically grown on flexible plastic substrates of polyethylene terephthalate (PET). By adjusting the electroplating conditions, we proposed a growth mechanism of Au nanostructures. Among them, the specific real surface area (RSA) of the Au NWs is the highest one (26100 cm2/g). This is due to the high aspect ratio of the one-dimensional NW structure. Further, as-fabricated Au nanostructures on flexible substrate were employed and used as electrode in biosensor and supercapacitor applications. For biosensor application, a thrombin-binding aptamer was immobilized on the surfaces of the Au nanostructures to form highly sensitive electrochemical impedance spectroscopic (EIS) as biosensors for thrombin recognition. The binding of thrombin to the aptamer was monitored by EIS in the presence of [Fe(CN)6]3-/4-(aq). The protein (1 – 50 pM) was detected linearly by the Au nanostructures. Among them, the Au NWs exhibited excellent thrombin detection performances (1130  pM-1 cm-2). The biosensor provided high sensitivity, selectivity, and stability due to its high surface area. For supercapacitor application, electrodes composed of ultrathin MnO2 (thickness 5 - 80 nm) spines on Au NW stems (length 10 - 20 μm, diameter 20 - 100 nm) were electrochemically grown on flexible PET substrates. The electrodes demonstrated high specific capacitance, high specific energy value, high specific power value, and long-term stability. In Na2SO4(aq) (1 M), the maximum specific capacitance was determined to be 1130 F/g by cyclic voltammetry (CV, scan rate 2 mV/s) using a three-electrode system. From a galvanostatic (GV) charge/discharge test using a two-electrode system, a maximum capacitance 225 F/g (current density 1 A/g) was measured. Even at a high charge/discharge rate 50 A/g, the specific capacitance remained at an extremely high value 165 F/g. The flexible electrodes also exhibited a maximum specific energy 15 Wh/kg and a specific power 20 kW/kg at 50 A/g. After five thousand cycles at 10 A/g, 90% of the original capacitance was retained. A highly flexible solid-state device was also fabricated to reveal its supercapacitance performance.