Preparation of bimetal-based FeNi-N/C catalyst and its electrocatalytic oxygen reduction performance
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Preparation of bimetal‑based FeNi‑N/C catalyst and its electrocatalytic oxygen reduction performance Wei Fang1 · Lu Liu1 · Ruiming Li1 · Rong Zhang1 · Wenyang Wang1 · Ding Zhang1 · Zixiang Cui1 Received: 5 November 2019 / Accepted: 30 March 2020 © Springer Nature Switzerland AG 2020
Abstract A kind of bimetal-based FeNi-N/C catalysts were prepared by combining ultrasonic reaction and high temperature heat treatment using dicyandiamide (DCD) as nitrogen source, FeCl3·6H2O and Ni(OAc)2·4H2O as bimetal source, BP2000 as carbon carrier. The composition and structure of the catalysts as-prepared were characterized by XRD, FT-IR and XPS. The catalytic activity of the catalysts on the oxygen reduction reaction(ORR) under alkaline conditions were tested by using linear sweep voltammetry (LSV) with a rotating disk electrode, and the prepared conditions, active site composition, the stability and methanol resistance of the as-prepared catalysts and the kinetic ORR mechanism were studied successively. The results show that the best FeNi-N/C-800 catalytic activity for ORR with the onset potential of 0.965 V (vs. RHE). The number of transferred electrons in catalytic ORR process is between 3.59 and 3.98, indicating the 4e− dominated ORR mechanism and a direct conversion process from O 2 into H2O. The nature of the metal and the heat treatment temperature are important key factors in the preparation of the catalyst. From this work, Ni can be regarded as a catalyst for N and metal Fe atoms into the carbon support, and Fe-Nx-C (Fe bonds with pyridine-N) is the main active sites of the catalyst FeNi-N/C and a synergistic effect of the two sites of Fe-Nx-C and Ni-Nx-C enhances their catalytic activity for ORR further. Keywords Fuel cell · Electrocatalysis · Oxygen reduction reaction (ORR) · FeNi-N/C catalyst · Active sites
1 Introduction With environmental pollution and depletion of energy, it is imperative to develop non-polluting renewable energy sources and seek a kind of green and sustainable energy storage. Fuel cells have attracted much attention because they are green energy conversion technologies that directly convert chemical energy into electrical energy, which have the advantages of high energy density, safety and environmental protection [1–3]. However, the actual operating efficiency of the fuel cell is greatly reduced due to the slow kinetics and the high overpotential and the large energy required to consume in the bond cleavage
of the cathodic oxygen reduction process [4]. As an ORR catalyst, the following basic characteristics are necessary: high activity, good durability and cost effectivity. However, the currently used precious metal platinum (Pt) catalyst has low reserves, high cost, easy poisoning and deactivation, which severely limits its large-scale application in fuel cells [5]. Hence, it is necessary to develop a non-precious metal catalyst which is inexpensive, efficient and stable. In recent years, a large number of non-precious metal catalysts have been extensively studied. Among them, nitrog
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