Selective Electrochemical Oxygen Reduction to Hydrogen Peroxide by Confinement of Cobalt Porphyrins in a Metal-Organic Framework

Sustainable alternatives for the energy intensive synthesis of H2O2 are necessary. Molecular cobalt catalysts show potential but are typically restricted by undesired bimolecular pathways leading to the breakdown of both H2O2 and the catalyst. The confinement of cobalt porphyrins in the PCN-224 metal-organic framework leads to an enhanced selectivity towards H2O2 and stability of the catalyst. Consequently, oxygen can now be selectively reduced to hydrogen peroxide with a stable conversion for at least 5 h, illustrating the potential of catalysts confined in MOFs to increase the selectivity and stability of electrocatalytic conversions. A cobalt porphyrin was confined in a metal-organic framework (MOF) leading to highly selective oxygen reduction towards H2O2. Moreover, the confinement led to a high stability during the electrochemical production and buildup of H2O2 for at least 5 h. Overall, this work shows that the use of MOFs to confine molecular complexes as single-site catalysts is an effective tool to enhance the stability and selectivity for electrochemical conversions. image