(583en) The Effect of Support Materials On the Electrocatalytic Reduction of CO2 to CO

During the past few decades, the increasing level of CO₂ in the atmosphere has led to a number of undesired climate effects, e.g., global warming, rising sea levels, and more powerful storms.  Multiple strategies, such as carbon sequestration, switching to cleaner fuels, expanded utilization of renewable energy sources, and increasing the energy efficiency of buildings, need to be employed simultaneously to slow, or better, to stop this rise.^[1]  On the other hand, renewable energy sources that are less taxing on the environment need to be pursued to replace the energy currently produced from dwindling supplies of fossil fuels. However, renewable sources like wind and solar are intermittent, requiring load leveling strategies and/or energy storage at large scales, both of which are non-trivial at this time.

Electrochemical reduction of CO₂ into value-added products provides a means to store intermittent renewable energy and simultaneously recycle CO₂ as an energy carrier, thereby reducing CO₂ accumulation in the atmosphere.^[2]  The catalyst used determines overpotential, rate, and selectivity for the CO₂ conversion process.^[3]  Previously we have developed an electrolyte-flexible microfluidic platform to characterize catalysts for electrochemical reduction of CO₂ under realistic reactor conditions. An external reference electrode allows for individual analysis of cathode and anode performance.^[4]  Flexible control over the electrolyte facilitates testing of novel electrolytes with regard to electrode performance. Therefore, this microfluidic configuration allows for in-situ characterization of novel catalysts by immobilizing a catalyst on a gas diffusion electrode and testing it under realistic reactor conditions.  

Here, we will present our work on the use of support materials such as carbon black and titanium dioxide for catalysts applied in the electrochemical reduction of CO₂ to CO.  The synthesis, characterization and testing of metal oxide supported Ag catalysts will be reported.  Some of these supported catalysts exhibit current densities that are equal to or better than those measured for state of the art catalysts such as Ag nanoparticles, despite a significantly lower silver loading.  We also will report on the beneficial role different support materials play in the CO₂ electroreduction pathway.

[1] S. Pacala, R. Socolow, Science 2004, 305, 968-972.
[2] D.T. Whipple, P.J.A. Kenis, J. Phys. Chem. Lett. 2010, 1, 3451-3458.
[3] H.-R. M. Jhong, S. Ma, P.J.A. Kenis, Curr. Opin. Chem. Eng. 2013, accepted.
[4] D.T. Whipple, E.C. Finke, P.J.A. Kenis, Electrochem. Solid-State Lett. 2010, 13, B109-B111.