Capillary-Driven Formation of Iron Nanoparticles Embedded in Nanotubes for Catalyzed Lithium–Carbon Dioxide Reaction

Lithium–carbon dioxide (Li-CO2) batteries possess bifunctional applications in energy storage and greenhouse gases capture; however, the sluggish decomposition kinetics of discharge products during recharge impair battery lifespan, while severely raising Li-CO2 cells overpotentials. Hereby, we report a synthetic strategy for embedding iron (Fe) nanoparticles in nitrogen-doped carbon nanotubes (N-doped CNTs) (Fe NPs@N-CNTs) via capillary action of hemoglobin solution, and their potential as catalytic electrodes for efficient Li-CO2 cells. We elucidate under varying thermal conditions the conversion mechanisms by which Fe nanoparticles are incorporated into CNTs by capillary force. Compared with pristine cells, Li-CO2 cells employing Fe NPs@N-CNT catalysts deliver triple charge and discharge capacities, as well as stable cycle performance accompanied by lower charge polarization. By observing the reversible binding and disconnection between Fe and CO2 during ex situ characterization, it was revealed that Fe nanoparticles act as catalyst components. Our suggested method focuses on rational designing of catalyst-embedded nanotube composites and highlighting their potential applications in advanced energy and environmental devices.