Exploring Efficient Fe/N/C Electrocatalysts for Oxygen Reduction from Nonporous Interpenetrated Metal–Organic Framework Involving in Situ Formation of ZnO Templates

Abstract

Efficient Fe/N/C electrocatalysts for oxygen reduction reaction (ORR) have been prepared from a nonporous 8-fold interpenetrated metal–organic framework (Fe–Zn-TTPA) bearing dense Zn(II)–carboxylate coordination units. During pyrolysis, the Zn(II)–carboxylate moieties gradually decompose into nanosized zinc oxide (ZnO) particles, serving as thermally removal templates to tune the texture of carbon matrix via carbothermal reduction. With the assistance of in situ formed nanosized ZnO templates, the optimal Fe/N/C electrocatalyst, namely, Fe/N/C-1000-0.05, show well-dispersed ORR-active sites of iron carbide (Fe3C) nanoparticles and Fe–Nx species hosted by a hierarchical porous carbon matrix with dominant mesopores. In alkaline electrolyte, a higher ORR activity than the benchmark Pt/C was achieved (Eonset = 0.98 V vs reversible hydrogen electrode (RHE); E1/2 = 0.86 V vs RHE). Moreover, Zn–air battery using Fe/N/C-1000-0.05 as a cathode catalyst exhibits a peak power density of 130 mW cm–2 and outstanding durability with a slight decay by 3.1% at a current density of 5 mA cm–2 for 70 h.