A comparison between 2D and 3D cobalt-organic framework as catalysts for electrochemical CO reduction.

Electrocatalytic CO reduction, as an effective way to reduce the CO concentration, has gained attention. In this study, we prepared ZIF-67 nanoparticles and nanosheets and investigated them as electrocatalysts for CO reduction. It was found that ZIF-67 nanosheets, because of their two-dimensional morphologies, provide more under-coordinated cobalt nodes and have lower overpotentials for both hydrogen evolution and CO reduction reactions. Also, the rate-determining step for hydrogen evolution changes from Volmer for ZIF-67 nanoparticles to Hyrovsky for ZIF-67 nanosheets. Also, the presence of Mg ions in solution causes more facile CO reduction, especially for ZIF-67 nanosheets.