| Summary: | 碩士 === 輔仁大學 === 化學系 === 106 === We successfully used simple solution dispersion method to synthesize polyaniline (PANI)-based nanocomposites, in which the polyhedral oligomeric silsesquioxane (POSS) modified graphene oxide (GO), which abbreviates as PDGO, was incorporated. The nanocomposite materials were applied for anti-corrosion, and the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs).
In the first part, FTIR was used to identify the functional groups of PANI and PDGO. TEM analysis was used to evaluate the dispersibility of GO and PDGO in PANI matrix. As a result, the PANI-0.5%PDGO showed a better morphology than that of PANI-0.5%GO. XRD results cannot find any diffraction peaks, indicates the PDGO could effectively dispersion with exfoliated layers of PDGO in PANI matrix. The surface morphology was also studied by SEM. We used electrochemistry include Tafel plots, Bode plots, and Nyquist plots to evaluate the corrosion protection effects of nanocomposites. The corrosion inhibits mechanism of this system could be the synergistic effects include PANI induced inert passivation layer, barrier effect of layers PDGO, and the hydrophobic properties of incorporated POSS. Therefore, the nanocomposite materials could exhibit with excellent anti-corrosion properties. CV analysis investigated the electroactivity of PANI-based nanocomposites, which contributes to the formation of the passivation layer. Raman analysis identified the PANI induced passivation layer. The intensity of Raman for oxide layers was observed to have the same trends of electroactivity of PANI-based composites. Also, TGA results illustrate the thermal stability of nanocomposites improved by the incorporation of PDGO.
In the second part, we applied this series nanocomposite materials in the CEs of DSSCs. From TEM images, we can find that POSS modified-GO delaminates efficiently, and also find PANI particles well-deposited on the surface of modified-GO. The results indicate there would be PANI nanoparticles deposited on PDGO when we dispersed PDGO in PANI solution. From SEM images, we can find the PANI-0.5%GO show a meticulous spherical morphology, and PANI-0.5%PDGO show a more regular morphology. From AFM studies, we can see that PANI-0.5%PDGO obtained the lowest roughness, which indicates PANI-0.5%PDGO composite would be a smooth coating on the CEs with well-distributed PANI nanoparticles. For the studies of DSSCs, the device efficiency of PANI-0.5%PDGO CEs is 7.07%, which is the best one, even better than Pt, i.e., 7.05%. The IPCE of PANI-0.5%PDGO CEs showed the best incident photon-to-electron conversion efficiency. We also find that PANI-0.5%PDGO CE exhibited the lowest impedance among various composite CEs indicates the lowest internal resistance of the device. Therefore, we conclude that PANI-0.5%PDGO CE would have the possibility to replace expensive platinum CE.
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