Over the last 20 years, electrocatalytic carbon dioxide reduction has attracted attention because of the ability to use electricity from renewable energy sources such as wind, solar and wave.

Silver is considered a promising material for a carbon dioxide reduction catalyst because of it offers high selectivity—approximately 81%—and because it costs much less than other precious metal catalysts. Additionally, because it is inorganic, silver remains more stable under harsh catalytic environments.

The researchers found that the nano-porous silver electrocatalyst was 3,000 times more active than polycrystalline silver, a catalyst commonly used in converting carbon dioxide to useful chemicals.

The high activity is likely a result of a large electrochemical surface area (approximately 150 times larger) and intrinsically high activity (approximately 20 times higher) compared with polycrystalline silver. The intrinsically higher activity may be due to the greater stabilization of CO₂⁻ intermediates on the highly curved surface, resulting in smaller overpotentials needed to overcome the thermodynamic barrier, the researchers suggested.

To validate whether their findings were unique, the researchers compared the UD-developed nano-porous silver catalyst with other potential carbon dioxide electrocatalysts including polycrystalline silver and other silver nanostructures such as nanoparticles and nanowires.

Testing under identical conditions confirmed the non-porous silver catalyst’s significant advantages over other silver catalysts in water environments.

Selective conversion of carbon dioxide to carbon monoxide is a promising route for clean energy but it is a technically difficult process to accomplish. We’re hopeful that the catalyst we’ve developed can pave the way toward future advances in this area

—Feng Jiao

The research team’s work is supported through funding from the American Chemical Society Petroleum Research Fund and University of Delaware Research Foundation. Jiao has patented the novel application technique in collaboration with UD’s Office of Economic Innovation and Partnerships.

Jiao’s previous work includes developing novel cathode materials to boost the energy storage of lithium-ion batteries, which are used in items ranging from laptops to electric cars, through a new synthetic method, ionothermal synthesis, for preparing lithium manganese phosphates with 3D nanoporous structures.

Resources

• Qi Lu, Jonathan Rosen, Yang Zhou, Gregory S. Hutchings, Yannick C. Kimmel, Jingguang G. Chen & Feng Jiao (2014) “A selective and efficient electrocatalyst for carbon dioxide reduction,” Nature Communications 5, Article number: 3242 doi: 10.1038/ncomms4242