| Summary: | 博士 === 國立臺北科技大學 === 能源與光電材料專班 === 106 === The carbon materials are classified into carbon nanotubes (CNT), graphene (GE), graphene oxide (GO), fullerenes, activated carbon (AC), and carbon foams. Among these, GE, GO, and CNTs are mainly used as potential candidates for electrochemical sensors, artificial muscles, environmental remediation, battery, and solar cells owing to their high mechanical strength, high surface area, higher electrical conductivity, and thermal stability. The transition metal oxides/conductive polymers are used in various fields due to their electro-catalytic activity, and higher conductivity compared to those of carbon based materials. To improve the power conversion efficiency (PCE), and electrochemical performance, we combine the carbon materials and transition metal oxides/conductive polymer, which may have an electro catalytic activity, and excellent conductivity owing to the merging of carbon and metal oxides/polymer. This thesis focus on the design, applications of solar energy conversion, and electro-catalytic activity of various nanocomposties such as, NGE/NiO, GO/SnO2, f-MWCNT/PIN/Ti2O3, and Fe3O4@f-MWCNTs. All nanocomposites were characterized by different analytical techniques such as X-ray diffraction patterns (XRD), Fourier transform infra-red spectroscopy (FT-IR), Raman spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and Energy-dispersive X-ray spectroscopy (EDX). (i) PCE of 9.75 % was achieved for this dye-sensitized solar cells (DSSCs) device, which is greater than that of DSSCs devices using GO/TiO2, and NiO/TiO2 based photo-anodes (PCE = 8.55, and 9.11 %). Also, the fill factor (FF) of the DSSCs devices using the NGE/NiO/TiO2 nanocomposite photo-anode was better than that of other photo-anodes. The NGE/NiO/TiO2 short-circuit photocurrent density (Jsc) of 19.04 mA cm-2, open circuit voltage (Voc) of 0.76 V, FF of 0.67 and dye absorption rate 0.21 x 10-6 mol cm-2. (ii) GO/SnO2 hybrid nanocomposite based photo-anode for DSSC observed PCE of 8.3%, and it is about 12% higher than that of un-doped TiO2 photo-anode. The equivalent short-circuit photocurrent density (Jsc) of 16.67 mA cm-2, open circuit voltage (Voc) of 0.77 V, and FF of 0.65 respectively. (iii) The fabricated f-MWCNTs-PIN/Ti2O3/GCE displayed an enhanced voltammetric response for oxidation towardsα-Lipoic acid (ALA) relative to that of f-MWCNTs/GCE, f-MWCNTs-PIN/GCE, Ti2O3/GCE, and a bare GCE. Under optimum conditions, the f-MWCNTs-PIN/Ti2O3/GCE showed a wide linear range at ALA concentrations of 0.39115.8 µM. The limit of detection of 12 nM, and sensitivity of about 6.39 µA µM-1cm-2. Applied possibility of the sensor has been confirmed in vegetable samples. (iv) The modified Fe3O4@f-MWCNTs/GCE showed an enhanced current (Ipa) response towards OPD relative to that of a Fe3O4/GCE, f-MWCNTs/GCE, and a bare GCE. Under optimum conditions, the Fe3O4@f-MWCNTs/GCE showed a wide linear range of 0.6-80 µM at OPD concentrations of 0.6-80 µM. The limit of detection and sensitivity of the f-MWCNTs/GCE, Fe3O4/GCE sensor were found to be 50 µM, and 2.8002 µA µM-1cm-2, respectively. The developed sensor showed excellent accumulation time, good repeatability, and operational stability.
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