Nanoparticles of Fe2O3 and Co3O4 as Efficient Electrocatalysts for Oxygen Reduction Reaction in Acid Medium

Alves, Ismael Carlos Braga; Santos, Janaiane Ferreira dos; Viégas, Deracilde S. S.; Marques, Edmar P.; Lacerda, Cristina Broglia Feitosa de; Zhanga, Jiujun; Marques, Aldaléa Lopes Brandes

doi:10.21577/0103-5053.20190195

Cited by 12 publications

(13 citation statements)

References 42 publications

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“…In Figure 5B-D the electrode contained 4.8%Co-oxide + 5.2% Pt, i.e., almost half of the Pt mass vs. the reference Pt-based electrode. According to Figure 5B-D all our Co-based electrodes showed the same negative ORR half-wave potential (−0.13 V vs. Ag/AgCl)) This is in accordance with literature data for Cobalt-based electrodes [67] in alkaline, O 2 saturated, aqueous medium with 0.1 M NaOH (pH = 13.4). The highest current density J lim = 8.31 mA cm −2 at 1500 rad/s was achieved by the #Co2-based electrode in Figure 5C, at a potential E = −600 mV.…”

Section: Oxygen Reduction Reactionsupporting

confidence: 91%

Flame Spray Pyrolysis Co3O4/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction

et al. 2021

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The oxygen reduction reaction (ORR) is the rate-limiting reaction in the cathode side of fuel cells. In the quest for alternatives to Pt-electrodes as cathodes in ORR, appropriate transition metal oxide-based electrocatalysts are needed. In the present work, we have synthesized Co3O4 and CoO/Co3O4 nanostructures using flame spray pyrolysis (FSP), as electrocatalysts for ORR in acidic and alkaline media. A detailed study of the effect of (Co-oxide)/Pt ratio on ORR efficiency shows that the present FSP-made Co-oxides are able to perform ORR at very low-Pt loading, 0.4% of total metal content. In acid medium, an electrode with (5.2% Pt + 4.8% Co3O4), achieved the highest ORR performance (Jmax = 8.31 mA/cm2, E1/2 = 0.66 V). In alkaline medium, superior performance and stability have been achieved by an electrode with (0.4%Pt + 9.6% (CoO/Co3O4)) with ORR activity (Jmax = 3.5 mA/cm2, E1/2 = 0.08 V). Using XRD, XPS, Raman and TEM data, we discuss the structural and electronic aspects of the FSP-made Co-oxide catalysts in relation to the ORR performance. Cyclic voltammetry data indicate that the ORR process involves active sites associated with Co3+ cations at the cobalt oxide surface. Technology-wise, the present work demonstrates that the developed FSP-protocols, constitutes a novel scalable process for production of co-oxides appropriate for oxygen reduction reaction electrodes.

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Section: Oxygen Reduction Reactionsupporting

confidence: 91%

Flame Spray Pyrolysis Co3O4/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction

et al. 2021

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“…The band centered at 758 cm -1 in KCL-102 spectrum was previously assigned to ν(C-H) bending mode in HKUST-1, a copper trimesate [59]. Alves et al [60] reported the FT-IR spectra of nanoparticles of Co3O4: they observed the bands at 567 and 665 cm -1 which were related to the Co-O stretching vibrations. For Co2O3 nanoparticles, the vibrational band was observed at 560 cm -1 owing to the Co-O stretching vibration mode, and 668 cm −1 was the bridging vibration of the O-Co-O bond.…”

Section: Resultsmentioning

confidence: 95%

Water-Driven Structural Transformation in Cobalt Trimesate Metal-Organic Frameworks

et al. 2021

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We report on the synthesis and the characterization of a novel cobalt trimesate metal-organic framework, designated as KCL-102. Powder X-ray diffraction pattern of KCL-102 is dominated by a reflection at 10.2° (d-spacing = 8.7 Å), while diffuse reflectance UV-Vis spectroscopy indicates that the divalent cobalt centers are in two different coordination geometries: tetrahedral and octahedral. Further, the material shows low stability in humid air, and it transforms into the well-known phase of hydrous cobalt trimesate, Co3(BTC)2·12H2O. We associated this transition with the conversion of the tetrahedral cobalt to octahedral cobalt.

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“…Strong absorption bands at ≈565 and ≈661 cm –1 were observed in ZIF‐67‐CO and Ag@ZIF‐67‐CO due to the stretching of the Co 3+ O bond in the octahedral site and the stretching of Co 2+ O in the tetrahedral site of the spinel mode on the surface of the metal oxide structure, respectively. [ 55,56 ] Upon chemical grafting of the Ag@ZIF‐67‐CO, absorption bands at 980–1200 cm –1 appeared, attributed to the asymmetric stretching modes of SiOSi in APTES–Ag@ZIF‐67‐CO. [ 57,58 ] These FT‐IR spectroscopic results demonstrate the successful surface modification of Ag@ZIF‐67‐CO by APTES via chemical grafting to form APTES‐Ag@ZIF‐67‐CO.…”

Section: Resultsmentioning

confidence: 99%

Sensitive and Homogeneous Surface‐Enhanced Raman Scattering Detection Using Heterometallic Interfaces on Metal–Organic Framework‐Derived Structure

Lee

Shin

et al. 2022

Adv Materials Inter

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Here the use of heterometallic interfaces on metal–organic framework‐derived structures as surface‐enhanced Raman scattering (SERS)‐active substrates is investigated for sensitive and homogeneous SERS detection. Zeolitic imidazole framework‐67 (ZIF‐67) is grown on a conductive glass substrate via chemical bath deposition, followed by carbonization and oxidation to form ZIF‐67‐derived Co3O4 (ZIF‐67‐CO). For the sensitive and homogeneous SERS analysis, ZIF‐67‐CO is converted to the heterometallic interface Au–Ag@ZIF‐67‐derived Co3O4 (denoted as Au–Ag@ZIF‐67‐CO) via electrodeposition and successive chemical grafting. The optical properties of Au–Ag@ZIF‐67‐CO indicate a uniform and large‐scale distribution of both metals on the surface. Raman signals from the substrate are evenly enhanced based on the Raman intensity and shift mapping over a large area. Due to the multiple absorption bands of the Au–Ag@ZIF‐67‐CO substrate, signal enhancement can also be achieved with two different laser sources (532 and 785 nm) that are frequently used in SERS. As a result, concentration‐dependent and fingerprint SERS signals of small molecules such as 1,2‐bis‐(4‐pyridyl) ethylene, Nile blue A, and 1,1′‐diethyl‐2,2′‐cyanine iodide are obtained, and their signal enhancement factors are 104–105. Collectively, the use of heterometallic‐interfaced ZIF‐67‐CO will be a beneficial approach for collecting reproducible SERS signals of various target analytes.

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Nanoparticles of Fe2O3 and Co3O4 as Efficient Electrocatalysts for Oxygen Reduction Reaction in Acid Medium

Cited by 12 publications

References 42 publications

Flame Spray Pyrolysis Co3O4/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction

Flame Spray Pyrolysis Co3O4/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction

Water-Driven Structural Transformation in Cobalt Trimesate Metal-Organic Frameworks

Sensitive and Homogeneous Surface‐Enhanced Raman Scattering Detection Using Heterometallic Interfaces on Metal–Organic Framework‐Derived Structure

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