Ionic Liquid–Mediated Selective Conversion of CO ₂ to CO at Low Overpotentials

Abstract

Electroreduction of carbon dioxide (CO(2))--a key component of artificial photosynthesis--has largely been stymied by the impractically high overpotentials necessary to drive the process. We report an electrocatalytic system that reduces CO(2) to carbon monoxide (CO) at overpotentials below 0.2 volt. The system relies on an ionic liquid electrolyte to lower the energy of the (CO(2))(-) intermediate, most likely by complexation, and thereby lower the initial reduction barrier. The silver cathode then catalyzes formation of the final products. Formation of gaseous CO is first observed at an applied voltage of 1.5 volts, just slightly above the minimum (i.e., equilibrium) voltage of 1.33 volts. The system continued producing CO for at least 7 hours at Faradaic efficiencies greater than 96%.

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“…Nanostructured copper has been reported as an exclusive novel material for the electrochemical reduction of CO 2 into hydrocarbons with high Faraday efficiency and selectivity (33,34,42,(49)(50)(51)(52)(53). The onset potential for the reduction of CO 2 at porous copper foam was −1.0 V vs. Ag/AgCl with the formation of formic acid (HCOOH) initially ( Figure 1).…”

Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2 – The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates

“…Such organic-mediated reactivity with regards to the conversion of CO 2 to chemical fuels has been reviewed by Hu and coworkers [5]. The report describes the use of tetraalkylammonium salts [6], ionic liquids [7], and pyridinium derivatives [8] that have been shown to act as mediators in the selective (photo-) electrochemical reduction of CO 2 to products such as CO and methanol.…”

Verifying the Rechargeability of Li‐CO2 Batteries on Working Cathodes of Ni Nanoparticles Highly Dispersed on N‐Doped Graphene

“…Various physical and chemical methods are currently under development to capture thousands of tons of CO 2 gas emitted per year 2, 3. It is extremely attractive to utilize CO 2 in energy storage systems;4, 5, 6 therefore, Li‐CO 2 batteries have been proposed and studied in recent years 7, 8, 9, 10, 11…”