Cobalt Metal–Organic\nFramework Based on Two\nDinuclear Secondary Building Units for Electrocatalytic Oxygen Evolution

Abstract

The synthesis of a new microporous metal–organic\nframework\n(MOF) based on two secondary building units, with dinuclear cobalt\ncenters, has been developed. The employment of a well-defined cobalt\ncluster results in an unusual topology of the <b>Co</b>_<b>2</b><b>-MOF</b>, where one of the cobalt centers\nhas three open coordination positions, which has no precedent in MOF\nmaterials based on cobalt. Adsorption isotherms have revealed that <b>Co</b>_<b>2</b><b>-MOF</b> is in the range\nof best CO₂ adsorbents among the carbon materials, with\nvery high CO₂/CH₄ selectivity. On the other\nhand, dispersion of <b>Co</b>_<b>2</b><b>-MOF</b> in an alcoholic solution of Nafion gives rise to a composite\n(<b>Co</b>_<b>2</b><b>-MOF</b>@Nafion)\nwith great resistance to hydrolysis in aqueous media and good adherence\nto graphite electrodes. In fact, it exhibits high electrocatalytic\nactivity and robustness for the oxygen evolution reaction (OER), with\na turnover frequency number value superior to those reported for similar\nelectrocatalysts. Overall, this work has provided the basis for the\nrational design of new cobalt OER catalysts and related materials\nemploying well-defined metal clusters as directing agents of the MOF\nstructure.