460816 Optimal Pattern of Bimetallic Electrocatalysts for Efficient Conversion of Water and Carbon Dioxide to Hydrocarbons and Oxygenates

Thursday, November 17, 2016: 4:15 PM
Imperial B (Hilton San Francisco Union Square)
Meenesh Singh, Chemical Sciences Division, Lawrence Berkeley National Laboratory, CA, Yanwei Lum, Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, Ezra L. Clark, Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, CA, Joel W. Ager III, Lawrence Berkeley National Laboratory, Berkeley, CA and Alexis T. Bell, Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA

The electrochemical conversion of water and CO2 to renewable fuels offers a sustainable route to store intermittent solar energy and recycle CO2. Of the various electrocatalysts investigated to date, Ag and Au are known to be highly selective to CO and H2, and Cu is the metal exhibiting the highest selectivity to hydrocarbons and oxygenated compounds. However, the onset potentials for the production of hydrocarbons and oxygenates over Cu is ~ -1 V vs RHE. The higher overpotential for CO2 reduction over Cu is partly due to the higher activation barrier for the transfer of the first two electrons to produce CO. Therefore, the overpotential to produce hydrocarbons from CO is lower as compared to the reduction of CO2. Catalysts such as Au and Ag can reduce CO2 to CO at lower overpotential ~0.4 V vs RHE, which can be directly fed to Cu for the efficient conversion of CO to hydrocarbons. Such tandem operation requires optimal spatial arrangement of bimetallics- Ag and Cu. There are several factors that need to be considered to find the optimal pattern of such bimetallic catalysts. As the fractional area of Ag increases, the CO formation and thereby its utilization by Cu increases. However, the increase in the area of Ag also increases the net production of H2, which in turn decreases the net production of hydrocarbons. In the case of higher Ag to Cu area ratio, the utilization of CO by Cu decreases as the fractional area of Cu decreases. This talk will discuss the design principles and the optimal configurations of bimetallic electrocatalysts for the efficient conversion of CO2 to hydrocarbons and oxygenates.

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