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

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.