p-band regulation guides the free-standing porous carbon electrode for efficient Na-CO2 batteries

The Na-CO 2 batteries with low-cost resources and high energy density have attracted huge attention in Mars and deep ocean exploration, but the slow CO 2 reduction reaction (CO 2 RR) and CO 2 evolution reaction (CO 2 ER) kinetics severely limit their practical application. Developing free-standing cathodes and understanding the relationship between the catalyst's active center and activity are essential to address long-standing challenges. This manuscript explores the promising metal-free porous carbon as a catalyst. The porous carbon network vertically grows on the surface of free-standing carbon paper to maximum exposure to the active site and optimization of electron/electrolyte transfer. Moreover, the active center of the carbon catalyst is optimized by introducing nitrogen or sulfur hetero-atom to regulate the p -band center, which steers the orbital hybridization and accelerates CO 2 RR and CO 2 ER kinetics The p -band optimized free-standing porous carbon electrode shows outstanding cycling of 1000 h with a small voltage gap of 1.04 V and a large energy efficiency of 71.2 % at 10 uA cm −2 . This study provides a new strategy for designing and fabricating p -band guided free-standing electrodes aiming at high-performance and wearable Na-CO 2 batteries.