(66d) A Carbon Nanotube Supported Gold Catalyst for the Electroreduction of Carbon Dioxide (CO2)

The electrochemical reduction of carbon dioxide (CO₂) to value added chemicals (such as formic acid, carbon monoxide (CO), ethylene, and ethanol) has been proposed as a potential strategy for the utilization of excess anthropogenic CO₂ emissions.[1, 2] In particular, the electroreduction of CO₂ to CO seems interesting, as CO (either alone or in combination with H₂i.e., syngas) can be used as a platform chemical to produce a variety of hydrocarbons. However, even after a few decades of research, electrochemical systems that can produce CO via the electroreduction of CO₂ at industrially relevant rates (partial current density for CO >150 mA cm^-2) and low overall cell overpotentials (absolute value <1V),[3] remain difficult to develop.

In this presentation, we will report a supported gold (Au) catalyst that exhibits remarkably high activity (partial current density for CO ~158 mA cm^-2) at low cell overpotentials (~-0.94 V), for the electroreduction of CO₂ to CO. The catalyst was synthesized via an in situ chemical reduction of the Au precursor (chloroauric acid) on a polybenzimidazole wrapped carbon nanotube support. The electrochemical characterization was performed in a flow electrolyzer to avoid mass transfer limitations associated with the low solubility of CO₂ in aqueous solutions.[4] Furthermore, we will also discuss the effect of electrolyte composition (concentration and pH) with respect to increasing the activity and lowering the overpotential required for the electroreduction of CO₂ to CO on the supported Au catalyst. The mechanistic implications of such a behavior will also be discussed.

References:

[1] A.M. Appel, J.E. Bercaw, A.B. Bocarsly, H. Dobbek, D.L. DuBois, M. Dupuis, J.G. Ferry, E. Fujita, R. Hille, P.J.A. Kenis, C.A. Kerfeld, R.H. Morris, C.H.F. Peden, A.R. Portis, S.W. Ragsdale, T.B. Rauchfuss, J.N.H. Reek, L.C. Seefeldt, R.K. Thauer, G.L. Waldrop, Chem. Rev. 2013, 113, 6621-6658.

[2] H.R.M. Jhong, S. Ma, P.J.A. Kenis, Curr. Opin. Chem. Eng. 2013, 2, 191-199.

[3] S. Verma, B. Kim, H.R.M. Jhong, S. Ma, P.J.A. Kenis, ChemSusChem 2016, 9, 1972-1979.

[4] D.T. Whipple, E.C. Finke, P.J.A. Kenis, Electrochem. Solid-State Lett. 2010, 13, B109-B111.