An ingenious approach for ZIFs derived N-doped hierarchical porous carbon hybrids with FeCo alloy nanoparticles as efficient bifunctional oxygen electrocatalysts

Abstract

Abstract An ingenious approach is proposed to achieve exceedingly efficient bifunctional oxygen electrocatalysts of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Hierarchical porous structure constituted by nanotubes and nanobulks with high specific surface area and encapsulated FeCo alloy nanoparticles is successfully prepared via the hybrid of Fe(II)-doped ZIF-8 (FeZIF) and cobalt (III) acetylacetonate (Co(acac)3), which is greatly redound to mass transfer and electron transport. Interestingly, Co(acac)3 plays dual-roles during preparation process, which not only generates new metal species but improves porous structure. Moreover, FeZIF acts as a self-sacrificing template and iron source. Owing to the coaction of the unique porous structure, bimetal-N active sites and FeCo alloy, the resultant catalyst carbonized at 850\u202f°C exhibits a prominent ORR activity with a positive half-wave potential of 0.864\u202fV (vs the reversible hydrogen electrode, RHE), and a low operating potential of 1.675\u202fV at a current density of 10\u202fmA\u202fcm−2 for OER in alkaline media. The potential gap (∆E) of overall oxygen electrode is 0.81\u202fV, which surpass that of numerous non-noble metal-based catalysts reported to date, indicating a promising bifunctional oxygen electrocatalyst.