scholarly journals Hybrids of Reduced Graphene Oxide Aerogel and CNT for Electrochemical O2 Reduction

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1404
Author(s):  
Javier Hernández-Ferrer ◽  
Ana M. Benito ◽  
Wolfgang K. Maser ◽  
Enrique García-Bordejé
Keyword(s):  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Onset Potential ◽  
Reduced Graphene ◽  
O2 Reduction ◽  
Electrocatalytic Oxygen Reduction ◽  
Fe Nanoparticles ◽  
Reduced Graphene Oxide Aerogel ◽  
Electron Reduction ◽  
Hybrid Carbon

Carbon nanotubes (CNTs), graphene aerogels (GAs), and their hybrid (CNT-GA) prepared by hydrothermal treatment were tested in the electrocatalytic oxygen reduction reaction (ORR). The importance of porous structure derived from the combination of mesoporosity coming from CNTs with macroporosity stemming from GAs was evidenced because the hybrid carbon material exhibited synergistic performance in terms of kinetic current and onset potential. Different electrocatalysts were prepared based on these hybrids doped with nitrogen using different precursors and also supporting Fe nanoparticles. N-doped carbon hybrids showed higher electrocatalytic activity than their undoped counterparts. Nevertheless, both doped and undoped materials provided a mixed two and four electron reduction. On the other hand, the addition of a Fe precursor and phenanthroline to the CNT-GA allowed preparing an N-doped hybrid containing Fe nanoparticles which favored the 4-electron oxygen reduction to water, thus being an excellent candidate as a structured cathode in fuel cells.

Preparation of CuPc/RGO Nanocomposites and Their Electrocatalytic Behaviors for Oxygen Reduction Reaction

2016 ◽  
Vol 19 (4) ◽  
pp. 193-198
Author(s):  
Guofang Zuo ◽  
Peng Wang ◽  
Zhifeng Li ◽  
Jiandong Yang
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Copper Phthalocyanine ◽  
Reduction Reaction ◽  
Electrochemical Behaviors ◽  
Glass Carbon Electrode ◽  
Reduced Graphene ◽  
Electrocatalytic Oxygen Reduction ◽  
Glass Carbon ◽  
Π Stacking Interaction

In this paper, copper phthalocyanine/reduced graphene oxide (CuPc/RGO) nanocomposites were synthesized by aromatic π-π stacking interaction and well characterized by scanning electron microscopy (SEM) and fluorescence spectrometry. The composites were modified on the surface of glass carbon electrode (GCE) and their electrochemical behaviors of CuPc/RGO for electrocatalytic oxygen reduction reaction (ORR) were studied by cyclic voltammetry (CV). The study showed when the mass ratio of RGO to CuPc in composite achieved 1:1, the composite film performed excellent electrocatalytic activity towards the ORR.

scholarly journals Reduced Graphene Oxide Aerogel inside Melamine Sponge as an Electrocatalyst for the Oxygen Reduction Reaction

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 322
Author(s):  
Roman A. Manzhos ◽  
Sergey A. Baskakov ◽  
Evgeny N. Kabachkov ◽  
Vitaly I. Korepanov ◽  
Nadezhda N. Dremova ◽  
...  
Keyword(s):  
Composite Material ◽  
Graphene Oxide ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Reduction Reaction ◽  
Reduced Graphene ◽  
Reduced Graphene Oxide Aerogel ◽  
Graphene Oxide Aerogel ◽  
Average Size

A graphene oxide aerogel (GOA) was formed inside a melamine sponge (MS) framework. After reduction with hydrazine at 60 °C, the electrical conductive nitrogen-enriched rGOA-MS composite material with a specific density of 20.1 mg/cm3 was used to fabricate an electrode, which proved to be a promising electrocatalyst for the oxygen reduction reaction. The rGOA-MS composite material was characterized by elemental analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. It was found that nitrogen in the material is presented by different types with the maximum concentration of pyrrole-like nitrogen. By using Raman scattering it was established that the rGOA component of the material is graphene-like carbon with an average size of the sp2-domains of 5.7 nm. This explains a quite high conductivity of the composite obtained.

Oxygen Reduction Reaction Activity of Pyrochlore Oxide Electrocatalysts Prepared by Precipitation Method

2009 ◽  
Vol 421-422 ◽  
pp. 479-482
Author(s):  
Hideki Kawai ◽  
Kenji Yoshihara ◽  
Takayuki Konishi ◽  
Morihiro Saito ◽  
Jun Kuwano ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Heat Treatments ◽  
Precipitation Method ◽  
Onset Potential ◽  
Surface Areas ◽  
Heat Treated ◽  
Orr Activity ◽  
Electron Reduction

The Mn-doped pyrochlores Pb2Ru1.5Mn0.5O7- (PRMns) samples were synthesized by a precipitation method, followed by heat-treatments at temperatures of 300-800oC. Effects of the heat-treatments on their electrocatalytic activities for oxygen reduction reaction (ORR) were examined by semi-steady state voltammetry with a rotating ring-disk electrode in 0.1 M KOH solution at 70oC. The PRMns showed the best ORR activity for the 500oC-heat-treated PRMn. The onset potential of the ORR current was over 1.0 V vs RHE, and the efficiency of 4-electron reduction was almost 100%. The maximum in the ORR activity for the 500°C-heat-treated PRMn resulted from a trade-off effect between their crystallinity and specific surface areas.

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

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