Electrospun MOF-Based FeCo Nanoparticles Embedded in Nitrogen-Doped Mesoporous Carbon Nanofibers as an Efficient Bifunctional Catalyst for Oxygen Reduction and Oxygen Evolution Reactions in Zinc-Air Batteries

Abstract

Low-price, high-performance and strong-stability electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are highly significant in the application of clean energy devices like rechargeable zinc-air batteries and renewable fuel cells. In this paper, a Prussian blue analogue Co3­[Fe­(CN)6]2·nH2O (Co-Fe PBA), as a well-known member of the metal–organic framework family, was electrospun into polyacrylonitrile (PAN) nanofibers to obtain composite Co-Fe PBA@­PAN nanofibers. Nitrogen-doped carbon nanofibers encapsulated FeCo alloy nanoparticles (FeCo-NCNFs-Ts, T = 700, 800, 900 °C) were synthesized by pyrolysizing Co-Fe PBA@­PAN precursor at different temperatures under an argon atmosphere. The effects of different calcination temperatures and mass ratios between Co-Fe PBA and PAN on ORR/OER catalytic activity were explored. Among FeCo-NCNFs-Ts, FeCo-NCNFs-800 had the highest bifunctional electrocatalytic performance with a lower reversible overvoltage of 0.869 V between ORR (E 1/2) and OER (E j = 10 mA cm–2), excellent stability and methanol durability, which even exceeded those of Pt/C and RuO2. The superb bifunctional activity for FeCo-NCNFs-800 was comparable to that of non-noble electrocatalysts reported in recent literatures. Moreover, the zinc-air battery based on the FeCo-NCNFs-800 air-cathode catalyst had a high power density of 74 mW cm–2 and strong cycling stability (125 cycles for 42 h), which can be comparable to a Pt/C-RuO2 zinc-air battery. The impressive bifunctional activity on ORR and OER for the FeCo-NCNFs-800 catalyst in the zinc-air battery can be attributed to the synergistic effects of the one-dimensional fibrous structure, FeCo alloy nanoparticles, Co-N (pyridinic-N) active sites, and numerous mesopores.

Electronic modulation and interface engineering of electrospun nanomaterials‐based electrocatalysts toward water splitting

“…In fact, to tune the OER performance, the interface between the active electrocatalyst and CNFs is very important 171‐198 . Li et al 197 developed an electrospinning and carbonization process to prepare CoFe 2 O 4 nanoparticles encapsulated in N‐doped CNFs (CoFe 2 O 4 /NCNFs) as an OER electrocatalsyt.…”

Defect Engineering of Carbon‐based Electrocatalysts for Rechargeable Zinc‐air Batteries

“…[5] TM (e. g., Fe, Co, Ni, Cu, Mo, and W) and nitrogen co-doped carbon matrix (M-N-C) based/or contained catalysts have been demonstrated as one of the most promising bifunctional candidates toward OER and ORR. [71][72][73][74][75][76] Intrinsic carbon defect sites, such as vacancy or topological defects are also capable of providing unique sites for capturing metallic species. The huge difference in electronegativity between TMs and carbon atoms generates sufficient charge transfer to make such structural units (intrinsic defectcaptured isolated metal species) as electrocatalytic active centers.…”

“…[40,80] In addition, both the metal-organic-frameworks (MOFs) and covalent organic frame-works (COFs) are also considered as promising precursors for rational dispersion of metals into carbon scaffolds. [18,63,71,81]…”

“…This interaction can effectively inhibit the cathodic corrosion process and make the catalyst have higher durability and chemical stability [5] . TM (e. g., Fe, Co, Ni, Cu, Mo, and W) and nitrogen co‐doped carbon matrix (M‐N‐C) based/or contained catalysts have been demonstrated as one of the most promising bifunctional candidates toward OER and ORR [71–76] . Intrinsic carbon defect sites, such as vacancy or topological defects are also capable of providing unique sites for capturing metallic species.…”

Electrospinning Nanoparticles-Based Materials Interfaces for Sensor Applications

“…Both factors make NPs the ideal building blocks to fabricate electrospun sensor devices. In recent years, the applications of electrospinning technique to introduce NPs into/onto polymer fibers to prepare composite fibrous materials interfaces for sensors have been reported widely [23,24].…”