A polypyrrole derived nitrogen doped porous carbon support for an atomically dispersed Mn electrocatalyst for the oxygen reduction reaction

Abstract

Platinum group metal (PGM)-free catalysts are highly desirable for oxygen reduction reaction (ORR) in electrochemical energy conversion devices, towards large scale commercialization of this technology. Here, we report a facile design approach using polypyrrole (PPy) hydrogel to synthesize an efficient ORR electrocatalyst featuring atomically dispersed Mn coordinated to nitrogen on partially graphitic carbon (Mn–N–C). The Mn–N–C catalyst exhibited a half-wave potential of 0.82 V versus the reversible hydrogen electrode, along with a limiting current density of −4.68 mA cm⁻². The catalyst retains ≈87% of its original current during a short term durability test for 50 hours. Furthermore, the electron transfer number and H₂O₂ yield for the catalyst approach 3.85–3.95 and 7.60–2.54% respectively in the potential range 0.4–0.8 V vs. RHE. The simplified approach can be used for the synthesis of other M–N–C catalysts for various electrochemical applications.