For the reduction of CO2, catalysts containing highly rare precious metal elements have been used so far.However, these catalysts are moderately active, require a lot of energy, and produce substances other than carbon monoxide (CO).It has been desired to develop a highly active catalyst that produces only CO, which has many industrial uses, with low energy, and uses an inexpensive and general metal such as iron.

　The research group focused on the structure of an enzyme called "carbon monoxide dehydrogenase (CODH)" that exists in microorganisms.This enzyme exchanges CO2 and CO, and nickel and iron atoms can react with low energy by binding to one molecule of CO2 at the same time.All conventional catalysts have a structure containing only one metal ion, but we have developed a highly durable iron porphyrin dimer in which two metal ions are arranged at an optimum distance like this enzyme.In this iron catalyst, the overvoltage at which the electrochemical reduction reaction of CO2 starts was the lowest among all the complex catalysts reported so far, and the catalyst rotation rate showed an extremely large value.Moreover, when the constant potential reduction reaction of CO2 was carried out in a neutral solution, CO was selectively generated with a high electric efficiency of 2%.This catalyst is the world's first complex catalyst that has been proven to have such high catalytic stability and product selectivity.It is said that this is the first iron complex catalyst in the world to have high CO92 reduction activity in a neutral solution.

　This discovery is expected to contribute to the practical application of artificial photosynthesis using sunlight directly and the reduction of carbon dioxide by electric power generated by renewable energy, and also to serve as a design guideline for the development of even more active catalysts. ..