Hierarchical porous N,S-codoped carbon with trapped Mn species for efficient pH-universal electrochemical oxygen reduction in Zn-air battery

Abstract

Highly efficient and ultrastable nonprecious metal-based electrocatalysts are promising alternatives to platinum (Pt)-based catalysts in electrocatalyzing oxygen reduction reaction (ORR) process. In the present work, nitrogen and sulfur dual-doped hierarchically porous carbon with trapped Mn species (MnNSC-950) was fabricated, which integrates the modulation of the electronic structure for boosted intrinsic activity with the engineering of hierarchical porosity for enriched active sites. The MnNSC-950 shows a positive onset potential of 0.95 V and a large limiting current density of 5.4 mA cm−2, which can rival that of the commercial Pt/C catalyst in 0.1 M KOH, together with a robust long-term stability. Moreover, the MnNSC-950 as ORR catalyst in Zn-air battery achieves a high power density of 107 mW cm−2 and robust cycling performance over 150 h, exceeding that driven by Pt/C cathode. The excellent electrochemical performance is also shown in both neutral and acidic media. This work provides an enabling route to prepare non-noble metal-based catalysts featuring well-engineered geometric and component peculiarities for practical application of energy conversion systems.