Abstract
Recently, electrocatalysts for oxygen reduction reaction (ORR) as well as oxygen evolution reaction (OER) hinged on electrospun nanofiber composites have attracted wide research attention. Transition metal elements and heteroatomic doping are important methods used to enhance their catalytic performances. Lately, the construction of electrocatalysts based on metal-organic framework (MOF) electrospun nanofibers has become a research hotspot. In this work, nickel-cobalt zeolitic imidazolate frameworks with different molar ratios (NixCoy-ZIFs) were synthesized in an aqueous solution, followed by NixCoy-ZIFs/polyacrylonitrile (PAN) electrospun nanofiber precursors, which were prepared by a simple electrospinning method. Bimetal (Ni-Co) porous carbon nanofiber catalysts doped with nitrogen, oxygen, and sulfur elements were obtained at high-temperature carbonization treatment in different atmospheres (argon (Ar), Air, and hydrogen sulfide (H2S)), respectively. The morphological properties, structures, and composition were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Moreover, the specific surface area of materials and their pore size distribution was characterized by Brunauer-Emmett-Teller (BET). Linear sweep voltammetry curves investigated catalyst performances towards oxygen reduction and evolution reactions. Importantly, Ni1Co2-ZIFs/PAN-Ar yielded the best ORR activity, whereas Ni1Co1-ZIFs/PAN-Air exhibited the best OER performance. This work provides significant guidance for the preparation and characterization of multi-doped porous carbon nanofibers carbonized in different atmospheres.
Highlights
Introduction distributed under the terms andWater splitting, metal-air batteries, and fuel cells are notable renewable energy technologies that rely heavily on oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)
The catalytic activities of OER and ORR were characterized by linear sweep voltammetry (LSV) curves set at 10 mV·s−1 scan rates [32]
Nix Coy -ZIFs/PAN nanofiber precursors were synthesized by simple electrospinning
Summary
Metal-air batteries, and fuel cells are notable renewable energy technologies that rely heavily on oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Nanomaterials 2022, 12, 832 reduction together with oxygen evolution catalysts is very important to improve their efficiencies. Many electrospun nanofiber catalysts with different properties were prepared by transition metal and heteroatomic doping. A variety of highperformance oxygen electrocatalysts were prepared by changing the composition and carbonization conditions of MOF materials [24]. The OER and ORR properties of bimetallic MOF electrospun structures show good dual-function performance [28]. It is paramount to study the structure, composition, and properties of catalytic materials under different carbonization atmospheres for high-performance catalyst development. For the first time, the assessment of bi-metal (nickel-cobalt) zeolitic imidazolate frameworks (NiCo-ZIFs) electrospun carbon nanofibers under three different atmospheres in one work. Afterwards, the multi-doped porous carbon nanofiber catalysts for OER and ORR were obtained by carbonization in different atmospheres (Ar, Air, and H2 S). The OER and ORR catalytic effects of various samples under different conditions were investigated
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