New catalyst turns greenhouse gases into useful chemicals

Scientists have discovered a new method to convert harmful greenhouse gases into chemicals which can produce synthetic fuels, while reducing industrial carbon dioxide emissions by up to 40 per cent.
Researchers at the University of Delaware have developed a highly selective catalyst capable of electrochemically converting carbon dioxide - a greenhouse gas - to carbon monoxide with 92 per cent efficiency.
The resulting carbon monoxide can be used as an industry feedstock for producing synthetic fuels, while reducing industrial carbon dioxide emissions by as much as 40 per cent, researchers said.
"Converting carbon dioxide to useful chemicals in a selective and efficient way remains a major challenge in renewable and sustainable energy research," according to Feng Jiao, assistant professor of chemical and bio-molecular engineering and the project's lead researcher.

The researchers found that when they used a nano-porous silver electrocatalyst, it was 3,000 times more active than polycrystalline silver, a catalyst commonly used in converting carbon dioxide to useful chemicals.
Silver is considered a promising material for a carbon dioxide reduction catalyst because it offers high selectivity - approximately 81 per cent - 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 exceptionally high activity is likely due to the new electrocatalyst's extremely large and highly curved internal surface, which is approximately 150 times larger and 20 times intrinsically more active than polycrystalline silver, Feng said.

Feng said the active sites on the curved internal surface required a much smaller than expected voltage to overcome the activation energy barrier needed to drive the reaction.
To validate whether their findings were unique, the researchers compared the 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.
Reducing greenhouse carbon dioxide emissions from fossil fuel use is considered critical. 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.