Preparation and Characterization of Multi-Doped Porous Carbon Nanofibers from Carbonization in Different Atmospheres and Their Oxygen Electrocatalytic Properties Research

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.

Manipulation of Waste-Activated Carbon Absorbers as Efficient Carbocatalysts for H2S Selective Oxidation

“…The catalytic performance of N@AC-T and w-AC in the selective oxidation of H 2 S was investigated to determine the promotion effect of N doping. The H 2 S conversion rates of w-AC and N@AC-T are 49.5, 88.5, 96.2, and 91.6%, respectively (Figure a), indicating that doping nitrogen into waste carbon can improve its catalytic activity. − Although the sulfur selectivity of N@AC-T samples decreases as carbonization temperature increases, N@AC-700 has the best desulfurization performance over all samples, with a sulfur yield of 78.6%. The specific relationship between the catalytic activity of N@AC-700 and the reaction temperature is shown in Figure b.…”

Self-Templating Synthesis of N/P/Fe Co-Doped 3D Porous Carbon for Oxygen Reduction Reaction Electrocatalysts in Alkaline Media

“…I D /I G of D-band (1337 cm −1 ) and G-band (1587 cm −1 ) with relative peak strength of NPFe-C is 0.93, it indicates that the material has both amorphous carbon and graphitized carbon with high degree of graphitization. In general, carbon-based electrocatalysts with a high graphitization degree increase the electrical conductivity, thus effectively improving the activity of the ORR [31].…”

The Scalable Solid-State Synthesis of a Ni5P4/Ni2P–FeNi Alloy Encapsulated into a Hierarchical Porous Carbon Framework for Efficient Oxygen Evolution Reactions

“…Inspired by the above background, we herein develop a method for the facile and scalable synthesis of a Ni 5 P 4 /Ni 2 P heterojunction and FeNi alloy hybrid encapsulated by three-dimensional hierarchical porous carbon (denoted by Ni 5 P 4 /Ni 2 P–FeNi@C) via a room-temperature solid-state grinding and sodium-carbonate-assisted pyrolysis strategy [ 18 ]. Unlike the previous works [ 17 , 18 , 19 , 20 , 21 , 22 ], the sodium-carbonate-assisted pyrolysis strategy can simultaneously induce the in situ generation of a template and pore-former. The process can not only impart a 3D porous nanocrystal-assembled carbon skeleton but also restrain the excessive coalescence of alloy particles and assist in implanting the FeNi alloy into the carbon framework [ 23 ].…”

“…However, bare alloy catalysts suffer from severe erosion and aggregation during electrochemical cycles; in particular, 3D transition metal alloys suffer serious instability in highly oxidative operating conditions and conditions with high levels of alkaline electrolytes, causing a drastic decline in catalytic performance [ 19 ]. The coupling/embedding of alloys with carbon-based substances seems an effective approach to enhancing the OER activity and stability [ 20 ] since carbon-based layers wrapped around the alloys prevent direct exposure to electrolytes and inhibit the agglomeration of adjacent metal particles [ 21 ]. Wei et al prepared a catalyst of NiFe alloy nanoparticles encapsulated in nitrogen-doped carbon nanofibers (NiFe@NCNFs) using an electrospinning method; this catalyst exhibited enhanced OER activity and durability.…”