The joint effect of electrical conductivity and surface oxygen functionalities of carbon supports on the oxygen reduction reaction studied over bare supports and Mn–Co spinel/carbon catalysts in alkaline media

Kostuch, Aldona; Jarczewski, Sebastian; Surówka, Marcin; Kuśtrowski, Piotr; Sojka, Zbigniew; Kruczała, Krzysztof

doi:10.1039/d1cy01115d

Cited by 17 publications

(9 citation statements)

References 88 publications

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“…The use of the above-mentioned solution may reduce the cost of vanadium flow-through battery cells, and thus increase the scale of their application. The reactivity of carbon-based electrocatalysts, for example, for the oxygen reduction reaction, is correlated with the functional oxygen groups present in the carbon materials [ 23 ] and can be successfully improved by using plasma. A clear correlation between their electrocatalytic activity and work function indicates that the latter can be a common descriptor of activity [ 24 ].…”

Section: Introductionmentioning

confidence: 99%

Functionalization of Graphite with Oxidative Plasma

Stelmachowski

Maj

Grzybek

et al. 2022

IJMS

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Surface-modified graphite is studied as an electrode material, an adsorbent, and a membrane component, among other applications. Modifying the graphite with plasma can be used to create relevant surface functionalities, in particular, various oxygen groups. The application of surface-oxidized graphite often requires its use in an aqueous environment. The application in an aqueous environment is not an issue for acid-oxidized carbons, but a discrepancy in the structure–activity relationship may arise because plasma-oxidized carbons show a time-dependent decrease in the degree of functionalization and related properties. Moreover, plasma-oxidized materials are often characterized in terms of their chemical and physical properties, most notably their degree of functionalization after plasma treatment, without contact with water. In this study, we used low-temperature plasma oxidation with pure oxygen and carbon dioxide and sample-washing with concentrated nitric and sulfuric acids. To evaluate the electronic properties of modified graphite, the work function changes and surface oxygen content were measured just after plasma modification and after water immersion. We show that water immersion drastically decreases the work function of plasma-treated samples, which is accompanied by a decrease in the number of radicals introduced by plasma. Our results demonstrate that the increase in stable work function as a result of plasma treatment, brought about by an increase in the surface oxygen species concentration, can be realized most effectively for the acid-washed graphite.

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Section: Introductionmentioning

confidence: 99%

Functionalization of Graphite with Oxidative Plasma

Stelmachowski

Maj

Grzybek

et al. 2022

IJMS

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“…Anion-exchange membrane fuel cells (AEMFCs) are regarded as a promising fuel cell technology because of their significant potential to replace the current expensive proton-exchange membrane fuel cell (PEMFC). − Recently, AEMFCs achieved remarkable power densities − with high voltage efficiencies, which makes the technology a serious contender for matured PEMFCs. Additionally, AEMFCs provide the opportunity to incorporate platinum group metal (PGM)-free − catalysts into the electrodes, as well as a greater variety of low-cost polymers for use as membranes . In spite of these benefits, major challenges still need to be addressed before this technology can be utilized in practical applications.…”

Section: Introductionmentioning

confidence: 99%

“…We specifically employed Pd, Ag, PdAg, and (MnCo) 3 O 4 as cathode catalysts to investigate the potential of oxygen radicals formed in different classes of catalysts. These catalysts are chosen as they have relatively high activities as cathodes in AEMFCs, − ,− and they are significantly different.…”

Section: Introductionmentioning

confidence: 99%

Operando EPR Study of Radical Formation in Anion-Exchange Membrane Fuel Cells

et al. 2023

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The alkaline operating environment of anion-exchange membrane (AEM) fuel cells (AEMFCs) makes it possible to employ a wide variety of catalysts, including platinum group metals (PGMs) as well as PGM-free materials. However, little is understood about radical formation during AEMFC operation with different catalysts and their implications. In this investigation, we utilized spin-trapping and electron-paramagnetic resonance measurements to measure and identify the radicals produced on selected PGM and PGM-free oxygen-reduction reaction catalysts. To the best of our knowledge, this is an original study exploring radical formation on different classes of catalysts in operando AEMFCs. This work highlights an unexplored radical degradation mechanism in AEMFCs and calls for innovative strategies in designing radical attack-resistant AEMs.

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“…However, due to the low conductivity of transition-metal oxides, the preparation process is easy to agglomerate, which leads to the restriction of electrochemically efficient active sites and other common issues . According to reports, the combination of transition-metal oxides and conductive substrates can not only enhance the conductivity of catalysts but also avoid the aggregation of active substances and effectively increase the catalytic activity of various metal oxides. − In addition, another approach to enhance OER activity is to bond catalysts and support the construction of heterojunctions through interface engineering, optimize interface electronic structure by interface coupling, and ultimately regulate the adsorption energy of intermediate products. − Therefore, in designing functional carbon supports, transition-metal oxides embedded on the surface of carbon nanotubes to construct heterojunction catalysts with different morphologies can enhance the catalytic performance.…”

Section: Introductionmentioning

confidence: 99%

In Situ Construction of MnO₂–Co₃O₄ Nanosheet Heterojunctions on Co@NCNT Surfaces for Oxygen Evolution

Zhao

Xie

et al. 2023

Inorg. Chem.

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Electrocatalytic water splitting is still circuitous and controversial because of the lack of highly active electrocatalysts to decrease the overpotential. Herein, we report a feasible method for constructing heterojunctions of MnO 2 −Co 3 O 4 nanosheets on Co@NCNT support surfaces (MnO 2 −Co 3 O 4 /Co@NCNT) by spontaneous redox reactions. Experimental results indicate that Co embedded in Co@NCNT can be used as the carbon support and anchoring sites for heterojunctions, thus exposing a large number of active sites, adjusting the surface electronic structure, changing the OER ratedetermining step of the catalyst, and reducing the reaction energy barrier. Besides, the in situ formation of MnO 2 −Co 3 O 4 nanosheets on Co@NCNT inhibits the loss and aggregation of the catalyst, leading to robust structural stability. Therefore, the synergistic effects of these factors provide multi-functional active sites to enhance the intrinsic activity and achieve maximum catalytic performances. To deliver a current density of 10 mA cm −2 , the catalyst of MnO 2 − Co 3 O 4 /Co@NCNT achieves an overpotential (η) of 303 mV in 1.0 M KOH media for OER. This simple redox strategy can be easily extended to prepare other ultrathin transition-metal oxide heterojunctions, which could be applied not only for water splitting but also for other energy conversion and storage technologies.

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The joint effect of electrical conductivity and surface oxygen functionalities of carbon supports on the oxygen reduction reaction studied over bare supports and Mn–Co spinel/carbon catalysts in alkaline media

Abstract: Supported manganese-cobalt spinel catalysts and the corresponding mesoporous carbon supports were examined in order to reveal the effect of electric conductivity and surface oxygen functionalities on oxygen reduction reaction (ORR)...

Cited by 17 publications

References 88 publications

Functionalization of Graphite with Oxidative Plasma

Functionalization of Graphite with Oxidative Plasma

Operando EPR Study of Radical Formation in Anion-Exchange Membrane Fuel Cells

In Situ Construction of MnO₂–Co₃O₄ Nanosheet Heterojunctions on Co@NCNT Surfaces for Oxygen Evolution

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The joint effect of electrical conductivity and surface oxygen functionalities of carbon supports on the oxygen reduction reaction studied over bare supports and Mn–Co spinel/carbon catalysts in alkaline media

Abstract: Supported manganese-cobalt spinel catalysts and the corresponding mesoporous carbon supports were examined in order to reveal the effect of electric conductivity and surface oxygen functionalities on oxygen reduction reaction (ORR)...

Cited by 17 publications

References 88 publications

Functionalization of Graphite with Oxidative Plasma

Functionalization of Graphite with Oxidative Plasma

Operando EPR Study of Radical Formation in Anion-Exchange Membrane Fuel Cells

In Situ Construction of MnO2–Co3O4 Nanosheet Heterojunctions on Co@NCNT Surfaces for Oxygen Evolution

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Product

Resources

About

In Situ Construction of MnO₂–Co₃O₄ Nanosheet Heterojunctions on Co@NCNT Surfaces for Oxygen Evolution