Defect‐Rich Carboxylic‐Functionalized Multiwalled Carbon Nanotubes/Conducting Polymer Hybrid Electrocatalyst for High Performance CO _{2 MARS} Breathing Batteries

The development of high‐performance Li‐CO 2 batteries is critical for next‐generation energy storage and CO 2 fixation technologies on Earth and for extraterrestrial applications. In this work, we report a polypyrrole/carboxyl‐functionalized carbon nanotube (PPY/CNT) hybrid as a bifunctional electrocatalyst for both CO 2 reduction (C RR ) and CO 2 evolution reaction (CER) for a Li‐CO 2MARS battery. The PPY/CNT catalyst shows a remarkable discharge capacity of 15,900 mAh g −1 , along with a low overpotential value of ~1.10 V at 50 mAg −1 . Furthermore, the catalyst exhibits stable cycling over 84 cycles with insignificant overpotential drop, validating the strong interfacial bonding between PPY and CNT. This study points out the PPY/CNT composite as a promising cathode for Li‐CO 2MARS batteries, offering a sustainable route for carbon fixation while simultaneously delivering high capacity, long cycle life, and energy‐efficient performance.