Regulation of Coordination Number over Single Co Sites: Triggering the Efficient Electroreduction of CO2

Abstract

The design of active, selective, and stable CO₂ reduction electrocatalysts is still challenging. A series of atomically dispersed Co catalysts with different nitrogen coordination numbers were prepared and their CO₂ electroreduction catalytic performance was explored. The best catalyst, atomically dispersed Co with two-coordinate nitrogen atoms, achieves both high selectivity and superior activity with 94 % CO formation Faradaic efficiency and a current density of 18.1 mA cm^-2 at an overpotential of 520 mV. The CO formation turnover frequency reaches a record value of 18 200 h^-1 , surpassing most reported metal-based catalysts under comparable conditions. Our experimental and theoretical results demonstrate that lower a coordination number facilitates activation of CO₂ to the CO₂^.- intermediate and hence enhances CO₂ electroreduction activity.

Keywords: CO2 reduction; electrocatalysis; metal single sites; metal-organic frameworks; renewable energy.