Work

Enhancing CO2 reduction efficiency with axial oxygen coordinated Ni-N4 active sites on hierarchical pore N-doped carbon

Year: 2024

Type: article

Abstract: The electrochemical reduction of carbon dioxide (CO 2 RR) is a promising strategy for achieving carbon neutralization. The Ni-N 4 site is well known as the active site in metal single atoms on N-doped carbon catalysts, while its symmetric charge distribution nature is not favorable for electron transfer and then hindering the efficient CO 2 RR. Herein, we constructed a Ni SA/CNs single-atom catalyst. Notably, it features unique Ni-N 4 O active sites, featuring one axial O atom and four planar N atoms, constituting a broken symmetrical electronic structure of Ni-N 4 sites. Furthermore, hierarchical pore structures were obtained with the assistance of NaNO 3 pore-forming agent during thermal treatment process, which promote electronic and mass transfer. And the resulting high specific surface area can host more Ni-N 4 O active sites. These specialized active sites promote the key intermediate (*CO) adsorption/desorption and suppresses hydrogen evolution . Consequently, the Ni SA/CNs catalyst exhibits a high turnover frequency (TOF) value, reaching 34,081 h −1 at -0.98 V vs. RHE. Additionally, it achieves an excellent CO Faradaic efficiency, exceeding 90%, over a wide potential range from -0.4 V to -1.0 V vs. RHE. This work not only offers a new method for the rational synthesize single-atom catalysts with unique Ni-N 4 O active sites, but also provides in-depth insight into the origin of catalytic activity of porous carbon-base catalysts.

Source: Chinese Chemical Letters

DOI: 10.1016/j.cclet.2024.110340