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