Porous N,S-codoped carbon architectures with bimetallic sulphide nanoparticles encapsulated in graphitic layers: Highly active and robust electrocatalysts for the oxygen reduction reaction in Al-air batteries

Abstract

To develop high-performance and low-cost electrocatalysts for the oxygen reduction reaction (ORR) in Al-air batteries, a promising hierarchical porous N,S-codoped carbon architecture with cobalt-nickel-sulphide nanoparticles immobilized inside was prepared using a simple double-phase encapsulation approach (DPEA), followed by a post heat treatment. The integrated hybrid architecture (Ni-Co-S@G/NSC) exhibited not only a comparable onset potential (0.94V vs. RHE) and half-wave potential (0.86V vs. RHE) but also a higher discharge voltage plateau (∼1.23V at discharge current density of 150mAcm−2) with superior stability to the commercial Pt/C catalyst in ORR and the full cell test. A combination of structural characterizations (e.g., XPS, RSS, XRD, SEM, HRTEM, and BET) and electrochemical analyses showed that the high ORR activity of the Ni-Co-S@G/NSC catalyst was attributed to its high surface area and pore volume, proper degree of the graphitization, and high content of active species combined with their synergetic interactions. Our findings show the advantages in utilizing a metal-organic framework with DPEA for designing well-dispersed, highly active and robust N,S-codoped porous carbons immobilized with sulphide NP catalysts for Al-air batteries.