CO2 electrochemical reduction catalyzed by bimetallic materials at low overpotential

Torelli, D. A., Francis, S.A. et al. Nickel–Gallium-Catalyzed Electrochemical Reduction of CO2 to Highly Reduced Products at Low Overpotentials. ACS Catalysis, 6, 2100-2104, DOI: 10.1021/acscatal.5b02888 (2016).

Scientific Achievement

Electrocatalytic reduction of CO2 to highly reduced C2 (ethylene and ethane) and C1 (methane) products was accomplished on three different phases of nickel-gallium films at low overpotentials.

Significance and Impact

This work demonstrates that it is possible to obtain high reactivity for CO2RR by use of bimetallic materials rather than their pure phases opening new venues of investigation into new CO2RR electrocatalysts.

Images are adapted with permission from Torelli, D. A., Francis, S.A. et al. Nickel–Gallium-Catalyzed Electrochemical Reduction of CO2 to Highly Reduced Products at Low Overpotentials. ACS Catalysis, 6, 2100-2104, DOI: 10.1021/acscatal.5b02888 (2016). Copyright (2016) American Chemical Society.

Images are adapted with permission from Torelli, D. A., Francis, S.A. et al. Nickel–Gallium-Catalyzed Electrochemical Reduction of CO2 to Highly Reduced Products at Low Overpotentials. ACS Catalysis, 6, 2100-2104, DOI: 10.1021/acscatal.5b02888 (2016). Copyright (2016) American Chemical Society.

Potential-dependent Faradaic efficiencies (solid lines) and current densities (dotted line) for CO2 reduction in 0.1 M Na2CO3 acidified to pH 6.8 with 1 atm CO2 (g)  to methane (Δ), ethane (x) and ethylene (□).

Potential-dependent Faradaic efficiencies (solid lines) and current densities (dotted line) for CO2 reduction in 0.1 M Na2CO3 acidified to pH 6.8 with 1 atm CO2 (g)  to methane (Δ), ethane (x) and ethylene (□).

Research Details

  • The different phase of NixGay films were prepared by drop-casting and characterized electrochemically and by SEM, XRD, and XPS.

  • In aqueous bicarbonate electrolytes at neutral pH, the onset potential for methane, ethylene, and ethane production on all three phases was found to be −0.48 V versus the reversible hydrogen electrode (RHE).

  • The onset potential for the reduction of CO2 to C2 products at low current densities catalyzed by nickel–gallium was >250 mV more positive than that of polycrystalline copper, and approximately equal to that of single crystals of copper.

  • Isotopic labeling experiments with 13CO2 confirmed that the detected products were produced exclusively by the reduction of CO2.

     Electrocatalytic activity was evaluated in a 2-compartment electrochemical cell.  A number of analytical techniques, including NMR and GC, were used to measure liquid- and gas-phase products.

Contact:  nslewis@caltech.edu