FeM/rGO (M = Ni and Cu) as bifunctional oxygen electrode

• Published in: Fuel (Guildford) 2024-07, Vol.368, p.131654, Article 131654
• Main Authors: Milikić, Jadranka, Nastasić, Ana, Rakočević, Lazar, Radinović, Kristina, Stojadinović, Stevan, Stanković, Dalibor, Šljukić, Biljana
• Format: Article
• Language: English
• Subjects: Bifunctional electrocatalysts; Oxygen electrode; Oxygen evolution reaction; Oxygen reduction reaction; Reduced graphene oxide; Transition metal
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2024.131654

[Display omitted] •FeNi/rGO showed two times higher OER current density than the IrO2 electrocatalyst.•FeNi/rGO gave η10 lower for 100 mV compared to IrO2 electrocatalyst during OER.•All three FeM/rGO electrocatalysts showed comparable ORR catalytic activity.•Good stability of FeM/rGO electrocatalysts during ORR was noticed. Three different iron-based electrocatalysts deposited on reduced graphene oxide (Fe/rGO, FeNi/rGO, and FeCu/rGO) were synthesized and examined for oxygen reduction and evolution reactions (ORR and OER, respectively) in alkaline media. X-ray powder diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy were used for a thorough investigation of physico-chemical properties of FeM/rGO electrocatalysts. XPS analysis indicated the presence of transition metals in higher oxidation states. Onset potentials during OER were found to be 1.51, 1.64, and 1.71 V for FeNi/rGO, FeCu/rGO, and Fe/rGO, respectively. Moreover, FeNi/rGO showed the highest OER current density (∼40 mA cm−2 at 2 V), two times higher than the benchmark OER electrocatalyst, IrO2, and the lowest Tafel slope (88 mV dec-1), lower than IrO2. The somewhat better catalytic activity of Fe/rGO for ORR in alkaline media compared to FeNi/rGO and FeCu/rGO was noticed. Tafel slopes of 105, 112, and 113 mV dec-1 during ORR were found for Fe/rGO, FeCu/rGO, and FeNi/rGO, respectively. Almost constant ORR current densities during chronoamperometric measurements were noticed for Fe/rGO and FeCu/rGO indicating stable performance.