The Fabrications of Nano-materials for Fuel and Solar Cell Applications

• Main Authors: Wang Di-Yan, 王迪彥
• Other Authors: Chen Chia-Chun
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/43951832302028213299

博士 === 國立臺灣師範大學 === 化學系 === 98 === The thesis attempts to develop an efficient electrocatalyst for DMFC and a novel material with near infrared absorption for solar cell appication. Following these concepts, the nanomaterials with different functions have been developed and shown their special properties on fuel cell or solar cell applications. In chapter 3, the new ternary Fe1-xPtMx nanocrystals were tested for their catalytic properties in the anodic electrode of a fuel cell. Their catalytic capability will be discussed elsewhere. Furthermore, the in situ studies of detailed chemical transformation from binary to ternary metal nanocrystals using X-ray absorption spectroscopy were on progress. Overall, our results have demonstrated a simple and rapid route for the syntheses of new catalysts based on metal alloy nanocrystals. In chapter 4, we have demonstrated that the Fe1-xPtRux NCs with various Fe/Ru ratios and alloying extent were well-controlled via chemical transformation in solid solution phase. Moreover, the solid solution Fe1-xPtRux NCs showed the unique catalytic performance for CO stripping and methanol oxidation in comparison with FePt NCs and commercial J-M PtRu catalysts. The enhanced electrocatalytic properties for methanol oxidation reaction can be attributed to that the electron density of Pt-CO bond in the Fe1-xPtRux NCs becomes weaker due to charger transfer from Fe and Ru to Pt atoms based on the density functional theoretic studies. Overall result has suggested that the chemical transformation reaction of the solid solution NCs is a quite useful method to modify the surface of the NCs and improve the catalytic activity in DMFC applications. In chapter 5, we have developed FePt alloy nanodendrites with high-index facets. The activity increased in the following order: FePt nanoparticles (111) < FePt nanocube (200) < FePt nanodendrites (311), indicating that the nanostructure with high-facet index possessed higher surface energy and demonstrated higher catalytic activity for ORR. We observe that the different coordination number and surface energy in the FePt hkl facets. The formation of different facets is attributed to the different degrees of surface reconstruction induced by oxygen adsorption. In chapter 6, A soft and biocompatible surface-enhanced Raman scattering (SERS) substrate was fabricated based on a three-dimensional (3D) structure of end-tethered poly(L-lysine) (“t-PLL”) with a brush-like configuration conjugated with silver nanoparticles (Ag NPs) (Ag NPs-t-PLL film). The conjugation procedures were carefully adjusted to generate the films with different interval widths (W) between Ag NPs and diameters (D) of Ag NPs. The resulting film was then characterized by zeta potential, CD spectropolarimeter and scanning electron microscopy. Furthermore, the studies of SERS enhancements using Ag NPs-t-PLL film as a substrate were performed. The significant increases of SERS enhancements have been obtained as W/D was decreased from 0.9 to 0.2. Our results not only afford a facile fabrication of a 3D soft substrate for SERS with high sensitivity and biocompatibility but also offer great potentials for the development of new biosensors. In chapter 7, we use new material for organic IR harvesting solar cells application based on poly(3-hexylthiophene)-iron disulfide (FeS2) nanocrystal(NCs) blend. The devices exhibited high photo-electric current conversion efficiency in infrared region (>700 nm)where the external quantum efficiency was 6.5% at wavelength 650nm and 1% at 700 nm. The photoresponsed measurement also indicated that onset of photogenerated edge was about 900nm, which is contributed by FeS2 NCs. The device power conversion efficiency under AM 1.5 100 mw/cm2 illumination was 0.13%, short circuit current density of 0.7mA/cm2, open circuit voltage of 0.44V and fill factor(FF) about 42.6%. This study also pointed out that FeS2 NCs:P3HT hybrid can provide a low cost, environment friendly and easy process organic solar cells. In chapter 8, We have demonstrated that solution-processed NIR photodetectors can be conveniently fabricated using films of FeS2 nanocrystals. With the I-V Characteristics and temporal photoresponse achieved, the FeS2-based device is suitable for NIR detector application. At light wavelength above 715 nm, a strong photocurrent is seen, with a photo-to-dark current ratio of 176. The characteristic times for rise and fall of photocurrent are 0.55s and 1.1s, respectively. Our device can work reproducibly in air. Considering the advantages of solution-process fabrication, low cost and environment friendly, the FeS2-based photodetector have high potential for use in near infrared range application