Supramolecular Modulation of Molecular Conformation of Metal Porphyrins toward Remarkably Enhanced Multipurpose Electrocatalysis and Ultrahigh-Performance Zinc–Air Batteries

Modulating the intrinsic catalytic activity of molecular catalysts to improve electrocatalytic performance is significant but challenging. Herein, a simple yet effective strategy to induce molecular flattening of Co (III) meso-tetra ( N -methyl-4-pyridyl) porphyrine (Co-TMPyP) by supramolecular assembly with chemically converted graphene (CCG) via synergistic electrostatic and π–π interactions is reported. This unique variation in molecular conformation leads to a shortened Co  N coordination bond and enhanced electron transfer from the porphyrin macrocycle to the metal ion, thereby optimizing the electronic structure of the catalytic active center in Co-TMPyP molecule. Thus, the flattened Co-TMPyP on CCG (Co-TMPyP/CCG) demonstrates remarkable electrocatalytic performance for the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER) simultaneously as a tri-functional molecular catalyst for the first time with a high half-wave potential of 0.824 V for ORR and a low overpotential for HER (320 mV) and OER (379 mV) at 10 mA cm –2 , respectively, not only much better than the pristine Co-TMPyP but also among the best results of molecular catalysts in each aspect of ORR, OER, and HER achieved thus far. As a practical demonstration, the Co-TMPyP/CCG catalyst is used to assemble a rechargeable Zn–air battery, which shows the highest specific capacity (793 mAh g –1 ) and power density (225.4 mW cm –2 ) among all molecular catalyst-based Zn–air batteries ever reported.