High Pressure Photoreduction of CO2: g-C3N4/Bi2WO6/rGO prepared by a microwave-assisted-hydrothermal method

• Main Authors: I-TingChen, 陳俋廷
• Other Authors: Shou-Heng Liu
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/t7u47v

碩士 === 國立成功大學 === 環境工程學系 === 107 === In recent years, the greenhouses gases (i.e., excessive CO2 emission) led to serious global climate change problems, e.g., greenhouse effect and extreme climate. Among various techniques for reduction of CO2 emissions, the photocatalytic conversion of CO2 into chemicals or fuels is considered one of the promising strategies to address this problem. Thus, it is important to explore a photocatalyst with stability, high efficiency, and low cost. In addition, considering most of the research about CO2 photoconversion was conducted at normal pressure, the effects of high pressure on photoreduction of CO2 are investigated in this study. In this work, photocatalytic reduction of CO2 to CO using modified GCN (denoted as MCN) and 3%rGO/MCN/Bi2WO6-Y% (Y = 25, 50, 75, 100) which are prepared via a microwave-assisted route is reported. The physical-chemical properties and morphology of the photocatalysts are characterized by various analytic tools and spectroscopies, including XRD, XPS, TEM, SEM, PL, FTIR, and UV-visible spectroscopy. For MCN samples, structure and morphology of the GCN can easily be modified by a microwave-assisted hydrothermal method in an ammonia solution at different temperatures (130, 150, 170, 190) for 60 min. The obtained pale-yellow samples, MCN-X are used as photocatalysts in the CO2 photoreduction under the light irradiation. Among the samples, the MCN130 sample shows the highest CO yield of 4.22 μmol/g. For the heterostructured catalysts, 3%rGO/MCN/Bi2WO6-Y% (Y = 25, 50, 75, 100) samples are also successfully synthesized through a microwave system. In the photocatalytic CO2 reduction experiments, it was found that the 3%rGO/MCN/Bi2WO6-100% possesses the superior activity (CO yield = 13.5 μmol/g) within 12 h. The reason may be due to the 3%rGO/MCN/Bi2WO6-100% possesses a smaller band gap, and higher surface area compared to other 3%rGO/MCN/Bi2WO6-Y% (Y= 25, 50, 75). In addition, the effects of different operating pressures on the photoreduction of CO2 catalyzed by 3%rGO/MCN/Bi2WO6-100% are also discussed.