Dual-functional Fe3O4-decorated porous carbon nanosheets for kinetics-enhanced aqueous zinc–iodine batteries

Aqueous rechargeable zinc-iodine batteries (ARZIBs) are highlighted as a favorable solution for energy storage in view of their sustainability, cost-effectiveness, and safety. Nonetheless, the practical implementation of ARZIBs is challenged by the sluggish iodine reduction reaction kinetics as well as the shuttling behavior of the soluble polyiodide substances. Herein, Fe 3 O 4 nanoparticles embedded in porous carbon nanosheets (Fe 3 O 4 NPs@PCNs) with high specific surface area (1407.8 m 2 g -1 ) are produced as the iodine host for ARZIB. This structure not only enhances iodine adsorption but also supports the electrocatalytic process for the reversible conversion of iodine. Both experimental evidence and theoretical analyses highlight the presence of the Fe 3 O 4 nanoparticles can be effective in accelerating the iodine reduction reaction reversibly, while simultaneously mitigating the shuttle effect of polyiodide ions. Consequently, the resultant ARZIBs exhibit a specific capacity of 269.8 mAh g -1 at 0.5 A g -1 , with 85% of this capacity contributed by the discharge platform. Additionally, the ARZIBs demonstrate rate capabilities, delivering 211.1 mAh g -1 at 20 A g -1 , minimal self-discharge, and cycling stability for 15,000 cycles. This performance is attributed to the synergistic effect of the catalytic activity of Fe 3 O 4 nanoparticles and the physical confinement provided by the carbon framework. The findings of this study illuminate the critical aspect of Fe 3 O 4 in transforming the non-polar carbon material into an efficient iodine host, paving the way for the realization of reversible ARZIBs. • Fe₃O₄ nanoparticles embedded in porous carbon nanosheets enable high iodine adsorption. • Dual catalysis-confinement effect achieves reversible I₂ conversion and inhibits polyiodide shuttling. • High capacity (269.8 mAh g⁻¹ at 0.5 A g⁻¹) with 85% from discharge plateau and 15,000-cycle stability. • Outstanding rate capacity with 211.1 mAh g⁻¹ at 20 A g⁻¹ and minimal self-discharge. • Combined experimental and DFT analyses reveal its dual catalytic/anchoring roles.