Many studies have focused on atomically dispersed metal-nitrogen-carbon (Me-N-C) catalysts owing to their unique chemistry and high catalytic activities. Me-N-C catalysts have active centers resembling metalloporphyrins; thus, being heterogeneous analogs of homogeneous catalysts, their catalytic characteristics can be described by organometallic principles. In this regard, the high electrochemical activity of Ni-N-C catalysts for carbon dioxide reduction reactions (CO2RRs) is particularly difficult to understand because Ni2+ is a d8 species with a chemically inert axial site for intermediate binding in a square-planar ligand field. To resolve such a conundrum, we investigated the effects of different coordination geometries and Ni spin states on CO2RR activities—both of which influence the chemical activity of the Ni center. We used the grand-canonical density functional theory (GC-DFT) and the occupation matrix control method to properly include a finite potential effect, and to control the oxidation state of the Ni center, respectively. We elucidated that the generation of Ni+ directly impacts the CO2RR activity by providing strong intermediate binding energies to the Ni center, and a defective coordination environment is essential for stabilizing the Ni+ oxidation state. Our present study identifying governing factors for the high catalytic activity of Ni-N-C catalysts provides a design principle to develop high-performing catalysts for CO2RR.
|Number of pages||8|
|Journal||Journal of Materials Chemistry A|
|Publication status||Published - 2022 Oct 3|
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2017M3D1A1039378, No. NRF-2017R1A5A1015365, No. NRF-2020R1C1C1008458, No. NRF-2021R1A5A1084921) and Korea Institute of Science and Technology Information (KISTI) National Supercomputing Center with supercomputing resources (KSC-2021-CRE-0277).
© 2022 The Royal Society of Chemistry.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)