Selective conversion of CO2 to CO with high efficiency using an inexpensive bismuth-based electrocatalyst

Abstract

The wide-scale implementation of solar and other renewable sources of electricity requires improved means for energy storage. An intriguing strategy in this regard is the reduction of CO2 to CO, which generates an energy-rich commodity chemical that can be coupled to liquid fuel production. In this work, we report an inexpensive bismuth-carbon monoxide evolving catalyst (Bi-CMEC) that can be formed upon cathodic polarization of an inert glassy carbon electrode in acidic solutions containing Bi(3+) ions. This catalyst can be used in conjunction with ionic liquids to effect the electrocatalytic conversion of CO2 to CO with appreciable current density at overpotentials below 0.2 V. Bi-CMEC is selective for production of CO, operating with a Faradaic efficiency of approximately 95%. When taken together, these correspond to a high-energy efficiency for CO production, on par with that which has historically only been observed using expensive silver and gold cathodes.

Figure 1

(a) Cyclic voltammogram in 1.0 M HCl and 0.5 M KBr containing 20 mM Bi³⁺. (b) SEM image recorded for a Bi-modified GCE.

Figure 2

(a) CV traces recorded for Bi-modified and bare GCEs in MeCN containing 20 mM [EMIM]BF₄; Inset: Bi-modified GCE in MeCN without IL. (b) Total current density (j_tot) profiles for Bi-CMEC and GCE at −1.95 V in MeCN. (c) Total current density (j_tot) Tafel plot for Bi-CMEC with 20 mM [BMIM]PF₆ in MeCN. All electrochemistry was performed using 0.1 M TBAPF₆ as electrolyte.