Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

• DOI: 10.1002/anie.202016024
• Publication Date: 2021-01-23T06:07:38Z
• Authors: Zuozhong Liang; Hongbo Guo; Guojun Zhou; Kai Guo; Bin Wang; Haitao Lei; Wei Zhang; Haoquan Zheng; Ulf‐Peter Apfel; Rui Cao
• Keywords: 01 natural sciences; 0104 chemical sciences

AbstractSynthesizing molecule@support hybrids is appealing to improve molecular electrocatalysis. We report herein metal–organic framework (MOF)‐supported Co porphyrins for the oxygen reduction reaction (ORR) with improved activity and selectivity. Co porphyrins can be grafted on MOF surfaces through ligand exchange. A variety of porphyrin@MOF hybrids were made using this method. Grafted Co porphyrins showed boosted ORR activity with large (>70 mV) anodic shift of the half‐wave potential compared to ungrafted porphyrins. By using active MOFs for peroxide reduction, the number of electrons transferred per O2 increased from 2.65 to 3.70, showing significantly improved selectivity for the 4e ORR. It is demonstrated that H2O2 generated from O2 reduction at Co porphyrins is further reduced at MOF surfaces, leading to improved 4e ORR. As a practical demonstration, these hybrids were used as air electrode catalysts in Zn‐air batteries, which exhibited equal performance to that with Pt‐based materials.