Energetic MOF-derived Fe3C nanoparticles encased in N,S-codoped mesoporous pod-like carbon nanotubes for efficient oxygen reduction reaction

The rational design of advanced oxygen reduction reaction (ORR) catalysts is essential to improve the performance of energy conversion devices. However, it remains a huge challenge to construct hierarchical micro-/meso-/macroporous nanostructures, especially mesoporous transport channels in catalysts, to enhance catalytic capability. Herein, motivated by the characteristics of energetic metal-organic frameworks (EMOFs) that produce an abundance of gases during high-temperature pyrolysis, we prepared a unique tetrazine-based EMOF-derived electrocatalyst (denoted as Fe3C@NSC-900) consisting of highly dispersed Fe3C nanoparticles and N,S-codoped mesoporous carbon nanotubes. The mesopore-dominated core-shell structure endows Fe3C@NSC-900 with excellent catalytic activity and efficient mass transfer. Thus, optimal Fe3C@NSC-900 demonstrates a high half-wave potential of 0.922 V and great stability in 0.1 M KOH, outperforming commercial Pt/C and most of the reported ORR catalysts. As far as we know, this work is the first application of a tetrazine-based EMOF derivative for the electrocatalytic ORR and is expected to offer some constructive insights into potential of EMOFs for new-generation catalyst design.