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

Abstract

AbstractModulating 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.