Heterocyclization Strategy for Construction of Linear Conjugated Polymers: Efficient Metal‐Free Electrocatalysts for Oxygen Reduction

Abstract

Abstract Exploring cost‐effective and efficient metal‐free electrocatalysts for the oxygen reduction reaction (ORR) is crucial for the development of energy conversion and storage technologies. Reported here is a novel heterocyclization strategy to construct efficient ORR catalysts based on linear conjugated polymers (LCPs), which are composed of N‐, S‐, or Se‐heterocycles. Among these polymers, the covalently linked pyridine and thiophene molecule ( P‐T ) with reduced graphene oxide (rGO) exhibits a remarkable half‐wave potential of 0.79 V (vs. RHE) and excellent electrochemical stability, which are among the highest values for metal‐free polymers as ORR catalysts. Density‐functional theory (DFT) calculations reveal that the molecule with a phenyl unit ( P‐Ph ) is catalytically inactive, and when a thiophene unit is introduced to replace the phenyl unit in the conjugated backbone it features highly efficient electrocatalytic active sites. More importantly, the well‐defined molecular structures and controllable active sites in the pyrolysis and metal‐free polymers highlight new opportunities for the catalytic metal‐free ORR.