Na–CO₂ batteries are prospective in energy storage and CO₂ recycling applications; development of a high-efficiency, low-cost electrocatalyst to promote CO₂ reduction and carbonate decomposition is extremely vital for practical Na–CO₂ batteries. Herein, a highly efficient cathode catalyst for rechargeable hybrid Na–CO₂ batteries is successfully synthesized by encapsulating highly dispersed Co/Co₉S₈ nanoparticles into carbon skeletons, consisting of biomass-derived S, N-co-doped hierarchically porous carbon (Co/Co₉S₈@SNHC). The conductive and hierarchically porous framework structure of the Co/Co₉S₈@SNHC can not only accelerate electron transport, electrolyte infiltration, and CO₂ diffusion but also can inhibit overgrowth and agglomeration of Co/Co₉S₈ nanoparticles and expose numerous high density of active sites, as well as offer sufficient space to store discharge products. Benefiting from the synergistic effect among S and N dopants, carbon defects, and Co/Co₉S₈ nanoparticles in robust porous carbon structure, the hybrid Na–CO₂ batteries displayed a low charge overpotential (only ~0.32 V) at 0.2 mA/cm² and repeatedly charged and discharged over 200 cycles at 0.1 mA/cm². Besides, an ultrahigh areal capacity of ~18.9 mAh/cm² was obtained at 0.5 mA/cm², the highest value to date for Na–CO₂ batteries. Meanwhile, the hybrid Na–CO₂ battery charging from Na₂CO₃@C catalytic cathode demonstrated the high catalytic activity of biomass-derived S,N-co-doped hierarchically porous carbon (Co/Co₉S₈@SNHC) for CO₂ reduction and carbonate decomposition. Given this finding, this work might open up a potential avenue for the reasonable design of low-cost and highly efficient catalysts for advanced metal-CO₂ batteries systems.

Na–CO ₂电池在能量存储和CO ₂回收应用中具有前景。开发高效，低成本的电催化剂以促进CO ₂还原和碳酸盐分解对于实用的Na–CO ₂电池至关重要。本文中，通过将高度分散的Co / Co ₉ S ₈纳米颗粒封装到碳骨架中成功地合成了可再充电混合Na-CO ₂电池的高效阴极催化剂，碳骨架由生物质衍生的S，N-co掺杂的分级多孔碳（Co / Co ₉ S ₈ @SNHC）。Co / Co的导电且分层多孔的骨架结构₉ S ₈ @SNHC不仅可以加速电子传输，电解质渗透和CO ₂扩散，而且可以抑制Co / Co ₉ S ₈纳米粒子的过度生长和聚集，并暴露出大量的高活性位点，并提供足够的空间存放放电产品。得益于强大的多孔碳结构中S和N掺杂剂，碳缺陷和Co / Co ₉ S ₈纳米粒子之间的协同效应，Na-CO ₂混合电池在0.2 mA / cm ² 并以0.1 mA / cm ²重复充电和放电200次。此外， 在0.5 mA / cm ²下获得了约18.9 mAh / cm ²的超高面积容量，这是迄今为止Na-CO ₂电池的最高容量。同时，由Na ₂ CO ₃ @C催化阴极充电的Na-CO ₂混合电池表现出生物质衍生的S，N-co掺杂的分级多孔碳（Co / Co ₉ S ₈ @SNHC）对CO的高催化活性。₂还原和碳酸盐分解。鉴于这一发现，这项工作可能为合理设计用于先进金属-CO ₂电池系统的低成本和高效催化剂开辟一条潜在途径。