Restructured Fe−Mn Alloys Encapsulated by N‐doped Carbon Nanotube Catalysts Derived from Bimetallic MOF for Enhanced Oxygen Reduction Reaction

Abstract

A set of novel catalysts FeMn/N‐CNTs that partly maintain the core‐shell structure have been prepared successfully by calcination of analogous MOF‐74, which has bimetallic species (Fe and Mn) and a cheap organic ligand (2, 5‐dihydroxylbenzoic acid, DHBA) with melamine as additional nitrogen source. These catalysts exhibit a distinctive microstructure of Fe−Mn alloys surrounded by N‐doped carbon nanotubes (CNTs). Electrochemical methods have been employed to investigate their activity in oxygen reduction reaction (ORR) in alkaline solution. The highest ORR performance of Fe3Mn1/N‐CNTs‐100 shows that the half wave potential is at 0.865 V and the kinetic current density (at 0.9 V) is 1.447 mA cm−2, which are higher than those of commercial Pt/C (0.855 V, 0.946 mA cm−2). In addition, Fe3Mn1/N‐CNTs‐100 is much more durable than commercial Pt/C under the conditions tested. The highly efficient ORR performance may be attributed to the unique microstructure and large surface area with appropriate pore size, as well as to the synergistic effects between the pyridinic N species and the Fe−Nx species that play important roles in ORR in alkaline solution. However, in acid medium, only Fe−Nx species catalyze ORR and pyridinic N species are limited to work as the active sites. This study may prompt others to explore the development of heteroatom‐doped CNTs surrounding particles as efficient catalyst for ORR and fuel cell applications.

Cobalt Nanoparticles Embedded in N, S Co‐Doped Carbon towards Oxygen Reduction Reaction Derived by in situ Reducing Cobalt Sulfide

“…When annealing with melamine, as displayed in Figure c, d and Figure S2, all samples of CoSMe‐X‐800 are shown as the structure of nanoparticle encapsulated into the nanotube, indicating that the nanotube are leaded by melamine pyrolysis. This statement is consistent with many previous reports about melamine pyrolysis and furthermore plentiful nitrogen atoms in melamine molecule are helpful to introduce the N species into as‐prepared carbon matrix, which can facilitate catalyzing ORR process.…”

NiCo Alloy Nanoparticles Anchored on Carbon Nanotube-Decorated Carbon Nanorods as a Durable and Efficient Oxygen Electrocatalyst for Zinc-Air Flow Batteries

“…Recently, nonprecious bimetallic materials (such as metal alloys), particularly, transition metal, − have gained noticeable attention as candidates for oxygen electrocatalysts due to their highly active catalytic trait toward ORR and OER. An army of reported works − has indicated that the bimetallic alloy catalysts display excellent electrocatalysis compared to their individual entity.…”

Synthesis and Performance of MOF-Based Non-Noble Metal Catalysts for the Oxygen Reduction Reaction in Proton-Exchange Membrane Fuel Cells: A Review

“…An MOF-74 precursor assembled from Fe/Mn and a cheap organic ligand (2,5-dihydroxyterephthalic acid) were combined with melamine and heated at 800 °C in a flow of N 2 to generate a core–shell catalyst denoted as Fe 3 Mn 1 /N-CNTs-100 [ 107 ]. SEM and TEM imaging showed that many 80-nm-diameter CNTs were formed during pyrolysis.…”