Enhancing Electrocatalysis of CO2 to Ethanol via Intercalated Electron Boosters in an Atomically Dispersed Ca–N4-Doped Graphene Bilayer

We report the development of atomically dispersed Ca–N₄-doped graphene bilayers with single intercalated alkaline earth metal (AEM) atoms, denoted as CaN₄–AEM–CaN₄, designed to enhance the electrocatalytic conversion of CO₂ to C₁ and C₂ products. These catalysts significantly improve the CO₂ reduction reaction (CO₂RR) activity and fine-tune the selectivity between C₁ and C₂ pathways. Based on our theoretical findings, we propose an electron transfer mechanism where AEM atoms serve as electron donors across both layers during nonadsorbed intermediate processes and as electron boosters that facilitate electron transfer from the nonadsorbed to the adsorbed layer during adsorption, thereby enhancing catalytic performance. AEMs also influence the reaction pathways, promoting the formation of more valuable C₂ products by adjusting selectivity. Among the CaN₄–AEM–CaN₄ systems, CaN₄–Sr–CaN₄ stands out with a superior limiting potential (−0.93 V), demonstrating exceptional electrochemical catalytic activity for CO₂-to-ethanol conversion. This study underscores the potential of CaN₄–AEM–CaN₄ catalysts for enhancing multicarbon CO₂RR and provides key insights into the electron transfer mechanisms that drive their activity and selectivity.