Abstract
The electrochemical carbon dioxide reduction reaction (CO_2RR) represents a promising strategy for converting CO_2 into CO. Atomically dispersed transition metal sites have an exceptional ability to activate CO_2. However, the strong hybridization between the 3d orbitals of these transition metals and the 5σ or 2π* orbital of CO significantly impedes *CO desorption, thereby limiting the overall CO generation activity. In contrast, s-block metals, with diffuse 3s electron clouds, exhibit weaker interactions with *CO. Nevertheless, their practical application is hindered by the high energy barrier associated with the formation of the *COOH intermediate. To address these challenges, a fluorine(F)-tuned magnesium single-atom catalyst (Mg-SAC) is developed. Remarkably, this catalyst achieved a CO Faraday efficiency of 97.3% and a current density of 260.4 mA cm~(-2) at -0.4 V vs the reversible hydrogen electrode in a flow cell, surpassing the performance of most state-of-the-art SACs and transition metal catalysts reported in the literature. Mechanistic studies reveal that *CO desorption onMg sites is significantly easier compared to that on Fe and Co sites. Furthermore, the incorporation of F atoms modifies the electronic structure of the MgN4 sites, substantially lowering the energy barrier for the formation of the critical *COOH intermediate.
NETL
NSTL
Wiley