Universal Formation of Single Atoms from Molten Salt for Facilitating Selective CO2 Reduction

Abstract

AbstractClarifying the formation mechanism of single‐atom sites guides the design of emerging single‐atom catalysts (SACs) and facilitates the identification of the active sites at atomic scale. Herein, a molten‐salt atomization strategy is developed for synthesizing zinc (Zn) SACs with temperature universality from 400 to 1000/1100 °C and an evolved coordination from Zn‐N2Cl2 to Zn‐N4. The electrochemical tests and in situ attenuated total reflectance‐surface‐enhanced infrared absorption spectroscopy confirm that the Zn‐N4 atomic sites are active for electrochemical carbon dioxide (CO2) conversion to carbon monoxide (CO). In a strongly acidic medium (0.2 m K2SO4, pH = 1), the Zn SAC formed at 1000 °C (Zn1NC) containing Zn‐N4 sites enables highly selective CO2 electroreduction to CO, with nearly 100% selectivity toward CO product in a wide current density range of 100–600 mA cm−2. During a 50 h continuous electrolysis at the industrial current density of 200 mA cm−2, Zn1NC achieves Faradaic efficiencies greater than 95% for CO product. The work presents a temperature‐universal formation of single‐atom sites, which provides a novel platform for unraveling the active sites in Zn SACs for CO2 electroreduction and extends the synthesis of SACs with controllable coordination sites.