Nanowires assembled from iron manganite nanoparticles: Synthesis, characterization, and investigation of electrocatalyti
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Department of Chemistry, Middle East Technical University, Ankara 06800, Turkey Address all correspondence to this author. e-mail: [email protected]
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Received: 2 May 2019; accepted: 3 June 2019
The development of stable and effective earth-abundant metal oxide electrocatalysts is very crucial to improve competence of water electrolysis. In this study, iron manganite (FeMnO3) nanomaterials were synthesized as an affordable electrocatalyst for water oxidation reactions. The structural and chemical properties of FeMnO3 nanomaterials were studied by transmission electron microscopy, scanning electron microscopy, energydispersive X-ray, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, and Brunauer–Emmett–Teller analyses. The microscopy analyses show that the synthesized material has wire morphology, and assembly of approximately 70 nm nanocrystallites forms the wires. XRD patterns confirmed the bixbyite structure of FeMnO3. The potential utility of the synthesized FeMnO3 nanowires (NWs) as an electrocatalyst for oxygen evolution reaction (OER) was investigated in alkaline medium. The FeMnO3 NW modified fluorinated tin oxide (FTO) electrodes demonstrated promising OER activity with onset potential of 1.60 V versus reversible hydrogen electrode and overpotential of 600 mV at 10 mA/cm2 catalytic current density. FeMnO3 NW modified FTO electrode was also observed to be stable during long-term constant potential electrolysis. Therefore, this new material can be considered as a cost-effective alternative to noble metal electrocatalysts for water oxidation and other possible catalytic reactions.
Introduction Bimetallic oxide nanomaterials have garnered tremendous attention because of their interesting properties and capabilities owing to synergy between the two metals [1, 2, 3]. They offer opportunity of being produced from multiple combinations of metals in diverse structures (i.e., spinel, perovskite, mixed metal oxide) and morphologies (i.e., particle, wire, sheet) with capabilities superior to monometallic ones [4, 5, 6, 7, 8, 9, 10, 11, 12]. The properties of these materials have been intensely investigated for numerous nanotechnology applications, such as catalysis, supercapacitors, solar cells, and sensors [4, 5, 6, 7, 8, 9, 12, 13, 14, 15, 16, 17, 18, 19]. Among the potential applications of bimetallic oxide nanomaterials, their use as catalyst in electrochemical water splitting is particularly intriguing. They provide an attractive path to produce H2, which is a pivotal energy carrier for sustainable energy future [4, 20, 21]. However, the overall rate of water
ª Materials Research Society 2019
splitting process is hampered by sluggish kinetics and large overpotential requirement of anodic oxygen evolution reaction (OER) [4, 22, 23, 24]. Therefore, developing proper OER catalysts has become focus of profound research to address this challenge. Currently, precious metal oxides (RuO2, IrO2) have been reported to be the most efficient OER catalysts [4, 25].
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