Enhanced performance of molecular electrocatalysts for CO 2 reduction in a flow cell following K + addition.

Electrocatalytic CO 2 reduction is a key aspect of artificial photosynthesis systems designed to produce fuels. Although some molecular catalysts have good performance for CO 2 reduction, these compounds also suffer from poor durability and energy efficiency. The present work demonstrates the improved CO 2 reduction activity exhibited by molecular catalysts in a flow cell. These catalysts were composed of a cobalt-tetrapyridino-porphyrazine complex supported on carbon black together with potassium salt and were both stable and efficient. These systems were found to promote electrocatalytic CO 2 reduction with a current density of 100 mA/cm 2 and generated CO over at least 1 week with a selectivity of approximately 95%. The optimal catalyst gave a turnover number of 3,800,000 and an energy conversion efficiency of more than 62% even at 200 mA/cm 2 .