Pd-Catalyzed Electrohydrogenation of Carbon Dioxide to Formate: High Mass Activity at Low Overpotential and Identification of the Deactivation Pathway

Electrochemical reduction of CO2 to formate (HCO2 –) powered by renewable electricity is a possible carbon-negative alternative to synthesizing formate from fossil fuels. This process is energetically inefficient because >1 V of overpotential is required for CO2 reduction to HCO2 – on the metals...

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Veröffentlicht in:Journal of the American Chemical Society 2015-04, Vol.137 (14), p.4701-4708
Hauptverfasser: Min, Xiaoquan, Kanan, Matthew W
Format: Artikel
Sprache:eng
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Zusammenfassung:Electrochemical reduction of CO2 to formate (HCO2 –) powered by renewable electricity is a possible carbon-negative alternative to synthesizing formate from fossil fuels. This process is energetically inefficient because >1 V of overpotential is required for CO2 reduction to HCO2 – on the metals currently used as cathodic catalysts. Pd reduces CO2 to HCO2 – with no overpotential, but this activity has previously been limited to low synthesis rates and plagued by an unidentified deactivation pathway. Here we show that Pd nanoparticles dispersed on a carbon support reach high mass activities (50–80 mA HCO2 – synthesis per mg Pd) when driven by less than 200 mV of overpotential in aqueous bicarbonate solutions. Electrokinetic measurements are consistent with a mechanism in which the rate-determining step is the addition of electrochemically generated surface adsorbed hydrogen to CO2 (i.e., electrohydrogenation). The electrodes deactivate over the course of several hours because of a minor pathway that forms CO. Activity is recovered, however, by removing CO with brief air exposure.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja511890h