本研究以氧化石墨烯為光觸媒轉換二氧化碳為高經濟價值碳氫化合物，並為了提升二氧化碳轉換效率，加入小能隙之高分子以拓寬光吸收範圍從紫外光區域至可見光區域。分別探討高分子與氧化石墨烯混合比例、高分子顆粒大小以及氧化石墨烯能隙大小對二氧化碳光催化還原效率之影響。本研究結合紫外光-可見光光譜儀與紫外光光電子能譜(UPS)，量測光觸媒之價電帶及導電帶位置；以X光光電子能譜分析儀(XPS)及傅里葉轉換紅外光譜(FTIR)分析氧化石墨烯之表面成分及官能基種類。最後，將製備完成之光觸媒樣品進行二氧化碳光催化實驗。
第一部分為加入P3HT於氧化石墨烯，P3HT的加入不只會增進光吸收，還會與氧化石墨烯產生異質結，減少電子-電洞對再結合。其中以3 wt% P3HT/iGO之光觸媒，在六小時照光反應下具有最高碳氫化合物總產量3.09 μmole/g-catalyst及量子效率0.0039%，為自製氧化石墨烯的2.8倍。藉由光激發瑩光光譜與P3HT/iGO之分光效率結果，可得知P3HT/iGO為type II 異質結結構，其中P3HT於觸媒中為電子供體(donor)，而氧化石墨烯則為受體(acceptor)。此外，結合二維光激發螢光光譜圖和時間解析光激發瑩光光譜，得以觀察到氧化石墨烯中P3HT奈米顆粒的分佈，這些數據表明導電高分子奈米球的分散性對於其光催化效率的重要性。
第二，為了更進一步改善氧化石墨烯之光吸收，本研究藉由改變還原劑（NaBH4）濃度來調整氧化石墨烯的能隙值（Eg），使其還原為部分還原氧化石墨烯（rGO）。由於碳氧官能基被還原之故，部分還原氧化石墨烯的能隙值從4.07降低到2.58 eV。從二氧化碳光催化還原結果來看，在0.1 M NaBH4處理的部分還原氧化石墨烯中，最佳乙醛產率為1.88 μmole/ g-catalyst，量子效率為0.0024％，是氧化石墨烯的1.7倍。此外，通過傅里葉轉換紅外光譜和X光光電子能譜分析結果，部分還原氧化石墨烯中之碳氧官能基百分比與其光催化活性相關。

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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