Challenges in CO2 Conversion to Selective hydrocarbons: Using Graphene Oxides and Related 2D Hybrids as Examples
Li-Chyong Chen/林麗瓊1*, Kuei-Hsien Chen/陳貴賢2
1Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
2Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
* presenting author:Li-Chyong Chen,
Global climate warming and environment pollution have stimulated scientists to develop innovative high-efficiency and eco-friendly energy technologies, as alternatives to the conventional combustion-based technologies currently used in many power plants and transportation vehicles. The vast amount of carbon dioxide (CO2) emission from the conventional coal-burning power plants is a significant environmental issue. Hence, photocatalytic conversion of CO2 to hydrocarbons makes possible simultaneously harvesting solar energy for production of fuels or useful chemicals, as well as reducing CO2 for a greener society, two birds with one stone for the pressing global energy and environmental problems of our time.

Here, I will present the challenges on CO2 reduction, especially, the materials that can function towards efficient photocatalytic conversion of CO2 to selective hydrocarbons close to practical application. Case studies using graphene oxides (GOs) and their related 2D hybrids, as photo-catalysts, will be presented. Several approaches have been employed to synthesize GOs and reduced GOs (rGOs) with tunable bandgap and band alignment with respect to the CO2 reduction level. The functionalities of the GOs/rGOs were investigated by UV-Vis, cyclic voltammetry, and x-ray photoemission spectroscopy.

Under visible light, the photocatalytic conversion of CO2 to methanol of GOs/rGOs is several-fold higher than that of TiO2 (e.g., commercial P-25). Further, metal and metal sulfides, especially the 2D materials such as MoS2, as well as optically active polymers, were deposited onto GO as co-catalysts or sensitizers, to enhance the photocatalysis reaction. Besides methanol, other selective hydrocarbons including acetaldehyde and ethanol were also detected. Total solar to fuel yield of ~200 times enhancement over that of P-25 has been achieved. In all these GOs-2D hybrids, the photo-catalytic performance is always much better than that of constituent component when used alone. Detailed preparation and characterization of the catalysts will be presented. The role and interplay of the constituent components will also be discussed.

Keywords: Solar Fuels, CO2 reduction, graphene oxide, 2D materials, photocatalytic