Manganese coordinated with nitrogen in aligned hierarchical porous carbon for efficient electrocatalytic oxygen reduction reaction in alkaline and acidic medium

A Mn coordinated with N atoms aligned hierarchical porous carbon catalyst is prepared through an inorganic metal salt sublimation doping strategy. Gelatin is served as a carbon source and N source, Ca2+ is acted as templates to establish aligned porous structure during carbonization. MnCl2 sublimates into gas to serve as Mn source after reaching the melting point. This method can effectively avoid the agglomeration of Mn atoms, which is beneficial to form Mn-N-x active sites. The prepared optimal catalyst exhibits a large specific surface area with an aligned hierarchical porous structure. XAFs result demonstrates that Mn coordinates with N atoms to form Mn-N-x configuration in the carbon structure. Notably, it exhibits outstanding catalytic ORR performance with a positive half-wave potential (0.86 V vs. RHE) and excellent durability, superior to Pt/C (20 wt%) catalyst under alkaline medium. Meanwhile, enhanced catalytic ORR performance and stability in an acidic medium are also achieved. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.