Porosity-Dependent Iodine Capture and Catalytic Conversion in a Pair of Isomeric Co-MOFs

The sustainable advancement of nuclear energy urgently requires the effective management of radioactive iodine, a hazardous byproduct with significant environmental and safety concerns. Traditional capture-and-store strategies fall short by treating iodine as waste, overlooking its potential for resource utilization. Here, we report a rationally designed bifunctional metal-organic framework (MOF) that synergistically combines high-capacity iodine capture with in-situ catalytic conversion into value-added chemicals. By selecting nitrogen/oxygen-rich ligands (4,4'-azopyridine and oxalic acid) and catalytically active cobalt nodes, we serendipitously obtained a pair of structural isomers: a nonporous compound 1 and a porous compound 2. This unique discovery provides an ideal platform to elucidate the critical role of the porosity. As anticipated, porous 2 exhibited substantially superior iodine adsorption in both vapor and solution phases compared to 1. More importantly, the open channels in 2 serve as an efficient nanoreactor, where absorbed iodine is catalytically converted by O₂ at Co sites into iodinated aromatic compounds. Furthermore, 2 showed excellent recyclability, maintaining its structural integrity and catalytic performance over four consecutive cycles. This work not only presents a high-performance material for integrated iodine capture and conversion but also, through a direct isomeric comparison, definitively demonstrates that open porosity is a prerequisite for the efficient iodine enrichment and subsequent catalytic transformation. These findings thus establish a novel design paradigm and compelling experimental evidence for advancing resource-oriented nuclear waste management.