Cobalt Metal–Organic Framework Based on Two Dinuclear Secondary Building Units for Electrocatalytic Oxygen Evolution

The synthesis of a new microporous metal–organic
framework
(MOF) based on two secondary building units, with dinuclear cobalt
centers, has been developed. The employment of a well-defined cobalt
cluster results in an unusual topology of the Co2-MOF, where one of the cobalt centers
has three open coordination positions, which has no precedent in MOF
materials based on cobalt. Adsorption isotherms have revealed that Co2-MOF is in the range
of best CO2 adsorbents among the carbon materials, with
very high CO2/CH4 selectivity. On the other
hand, dispersion of Co2-MOF in an alcoholic solution of Nafion gives rise to a composite
(Co2-MOF@Nafion)
with great resistance to hydrolysis in aqueous media and good adherence
to graphite electrodes. In fact, it exhibits high electrocatalytic
activity and robustness for the oxygen evolution reaction (OER), with
a turnover frequency number value superior to those reported for similar
electrocatalysts. Overall, this work has provided the basis for the
rational design of new cobalt OER catalysts and related materials
employing well-defined metal clusters as directing agents of the MOF
structure.