| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 105 === Facilitating light absorption and charge separation toward photocatalytic redox reaction of CO2 is considered to be an important challenge in enhancing its solar fuel production efficiency. In this study, we demonstrated serious of methods to improve solar to fuel efficiency, especially in carbon dioxide reduction reaction (CO2RR). Various methods were performed to obtain the catalyst properties, like Ultraviolet–Visible Spectroscopy and Ultraviolet Photoelectron Spectroscopy (UPS) were used to measure the valence band and the conduction band position and the absorption behavior of the hybrid photocatalyst. The X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyze the material chemical composition and functional groups of photocatalyst matrix. The GC-FID were used to measure the CO2 conversion efficiency over 6 hours photocatalytic reaction test.
First, conducting polymer was acted as co-catalytic or sensitizing role to to extend light absorption to visible range and create an exciton separation heterojunction with GO. The acetaldehyde was found to main products of photocatalytic CO2RR with best yield of 3.09 μmole / g-catalyst in 3 wt% P3HT/iGO and the quantum efficiency is 0.0039%, which is 2.8 times higher than used GO alone. Through the wavelength-dependent test, we concluded our hybrid catalyst interface exhibit type II heterojunction, which polymer work as electron donor and electron acceptor of iGO. Furthermore, Combining the confocal fluorescent microscopy and fluorescence lifetime imaging microscope (FLIM), we are able to examine the distribution of P3HT nanoparticles in GO matrix and exciton lifetime maps of our hybrid catalyst. Those data demonstrated the important of polymer dispersion toward to their photocatalytic efficiency.
Second, to further improved the light absorbing behavior, we tuning the bandgap (Eg) of graphene oxide into reduced graphene oxide (rGO). The wet chemical reducing was through changing reducing agent (NaBH4) concentration, the Eg of rGO was reduced from 4.07 to 2.58 eV due to the loss of ethers bond. From photocatalytic efficiency, the best yield is 1.88 μmole / g-catalyst with QE of 0.0024% in 0.1M NaBH4-treated rGO which was 1.7 times higher than GO. Furthermore, by examining chemical and rGO through FTIR and XPS, the oxygen functionality can be correlated into their catalytic activity.
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