18 October 2017
Clean energy research: Cobalt-based catalyst more efficient for CO2 to CO conversion
Published online 30 August 2015
Researchers reveal a new ‘more efficient’ catalyst for electrochemical reduction of CO2 to CO in water.
A team of researchers synthesized a series of cobalt-based organic catalysts that can efficiently convert aqueous carbon dioxide to carbon monoxide.
Reduction of carbon dioxide to carbon monoxide and subsequently to organic hydrocarbons that can be burned as fuel is one of the most sought-after processes in chemical industry.
Carbon dioxide dissolved in water can be reduced electrolytically by applying a potential difference which causes electrons from a negative electrode to be transferred to the dissolved carbon dioxide. However, the kinetically competing reduction of water itself renders this process inefficient.
A team of researchers from California, China and Saudi Arabia designed a catalyst to favour the carbon dioxide to carbon monoxide conversion so highly that the competing off-pathway is almost negligible, publishing their results in Science1.
The team designed new catalysts made up of repeating organic units called porphyrins containing a cobalt atom in their center, covalently linked together to form an extended network — or a Covalent Organic Framework (COF).
Their model catalyst produced almost twice the rate of product conversion per milligram of catalyst and showed over 10% increase in carbon dioxide selectivity than free cobalt porphyrin molecules in solution.
The team then proceeded to tune the structural characteristics of the catalyst such as pore size and cobalt atom content to further improve its catalytic properties – thereby also showing that the macroscopic properties of a heterogeneous catalyst can be strategically controlled using this molecular building-block approach.
Lin, S. et al. Covalent organic frameworks comprising cobalt porphyrins for catalytic CO2 reduction in water. Science http://dx.doi.org/10.1126/science.aac8343 (2015).