Synergistic Fe/Fe₃C@Fe‐NC@Carbon Nanotube Heterostructure for Enhanced CO₂ Capture and Mineral Recovery from Desalination Brine

Abstract Metal recovery coupled with CO₂ mineralization from sustainable sources, such as seawater, has garnered significant attention from environmental science and resource utilization perspectives. Herein, an earth‐abundant and efficient Fe/Fe₃C@Fe‐N‐codoped carbon@carbon nanotube (Fe/Fe₃C@Fe‐NC@CNT) hybrid cathodic catalyst is introduced for electrochemically extracting magnesium and calcium from desalination brine while capturing CO₂ to produce valuable Mg(OH)₂ and CaCO₃. The Fe/Fe₃C@Fe‐NC@CNT, featuring the combination of single‐atomic Fe sites and graphitic layer‐wrapped Fe/Fe₃C nanoparticles encapsulated within N‐doped mesoporous carbon tubes, achieves over 90% of Ca²⁺ and Mg²⁺ metal cations recovery efficiency at 25 mA cm⁻² for 6 h. More importantly, the Fe/Fe₃C@Fe‐NC@CNT hybrid catalyst efficiently suppresses the competitive hydrogen evolution side reaction even at high currents and boasts a wider operating potential range compared to benchmark Pt/C, enhancing the metal recovery efficiency and CO₂ capture capability. These findings underscore the potential of the Fe/Fe₃C@Fe‐NC@CNT hybrid catalyst in revolutionizing brine management and waste stream handling, offering a promising and sustainable solution to these critical environmental challenges.