Better reduction of aqueous carbon dioxide  

A team of researchers have found an improved catalyst to make the conversion of carbon dioxide to carbon monoxide — one of the most sought-after reactions in modern chemistry — more efficient. 

Plants can perform photosynthesis, the remarkable ability to convert carbon dioxide from the atmosphere to organic materials using energy from sunlight. For years, chemists have attempted to mimic such a process.

Instead of light, electricity can be used to reduce CO₂ to CO, which in turn can be further reduced to organic hydrocarbons, but this needs an electrocatalyst, which facilitates the transfer of electrons from an electrode to a reactant.

Publishing in Angewandte Chemie¹, a team of researchers from the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia show that electrocatalysts made of an alloy of copper and indium are good candidates. 

The team prepared a copper-indium (Cu-In) electrode by immersing thermally oxidized metallic copper sheets in a solution containing indium. They then applied a voltage to simultaneously reduce the oxidized copper again — which improved properties of the catalyst — and electrochemically deposit metallic indium on to the electrode. 

When they used an aqueous solution saturated with dissolved carbon dioxide, they found that the Cu-In electrode had a carbon monoxide selectivity of 95%, compared to 30% using only oxidized copper, and showed remarkable stability over long reaction periods. Cu-In electrodes are also far less expensive than noble-metal-based electrodes. 

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