Distance produces beauty? regulating the distance of Fe atomic pairs to enhance electrocatalytic CO2 reduction

Abstract

Metal atom dispersed catalysts with high catalytic activity and accurate active sites are considered as promising catalyst materials for electrocatalytic CO₂ reduction reactions (CO₂RRs). Electronic structure regulation of active sites is a crucial means to improve the catalytic performance. Hence, Fe atom catalysts (FeN₄-Dx (x = 1, 2, 3, and 4)) with pairs of Fe atoms at different distances were constructed and the effect of distance on the catalytic performance was further investigated. Based on the structural stability and the activation effect for CO₂, the FeN₄-D1 structure (D1 = 2.39 Å) exhibited good CO₂RR selectivity and catalytic activity for producing CO. Moreover, due to the double active sites of Fe atomic pairs, the FeN₄-D1 structure had superior catalytic performance and selectivity for the CO₂RR to ethanol by the *CO–*CHO coupling with low reaction free energy. Combined with detailed calculations of the electronic structure, a suitable distance of Fe atomic pairs regulated the d-band center of active sites, which modified the interaction between the FeN₄-D1 structure and *CO intermediates and promoted the C–C coupling process. Therefore, the FeN₄-D1 structure can be used as a promising electrocatalyst for the CO₂RR to C₂ products and the accurate regulation method of active sites may provide new ideas for the design of efficient catalysts.