Activation of oxygen evolving perovskites for oxygen reduction by functionalization with Fe–N<sub>x</sub>/C groups

Rincón, Rosalba A.; Masa, Justus; Mehrpour, Sara; Tietz, Frank; Schuhmann, Wolfgang

doi:10.1039/c4cc06446a

Cited by 76 publications

(54 citation statements)

References 27 publications

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“…Inhibition studies were performed by immersing the catalyst in KSCN solution, since it is known that SCN − coordinates Fe 2+ and Fe 3+ ions strongly hence blocking their electrocatalytic activity. Thus, adding SCN − should induce a decreased performance of the catalysts if metal impurities were present and contributed to the actives sites . After evaluating the electrocatalytic activity towards ORR in 0.1 M KOH, the electrode was immersed for 1 h in 50 mM aqueous KSCN solution.…”

Section: Resultsmentioning

confidence: 99%

Nitrogen‐Doped Metal‐Free Carbon Materials Derived from Cellulose as Electrocatalysts for the Oxygen Reduction Reaction

et al. 2018

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Development of metal‐free carbon‐based electrocatalysts for reducing oxygen to water (ORR), preferentially following a 4 electron transfer pathway, is of high importance. We present a two‐step synthesis of N‐doped carbon‐based ORR electrocatalysts by using an efficient thermal treatment of hydrothermally carbonized cellulose in ammonia combining devolatilization, reduction and nitrogen doping. The influence of the synthesis temperature as well as of the ammonia concentration used during the synthesis on the electrocatalytic ORR activity was analyzed using bulk‐ and surface‐sensitive techniques. Correlation of electrocatalytic activity with structural features of the catalysts provided deeper mechanistic understanding and enabled us to optimize the synthesis conditions. The nitrogen‐doped metal‐free catalyst originating from the treatment in 100 % NH3 at 800 °C achieved a current density of −1 mA cm−2 at 0.83 V vs. RHE positioning it among the most active noble‐metal free and biomass‐based ORR catalysts reported so far.

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Section: Resultsmentioning

confidence: 99%

Nitrogen‐Doped Metal‐Free Carbon Materials Derived from Cellulose as Electrocatalysts for the Oxygen Reduction Reaction

et al. 2018

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“…[54] The poisoning agents play a role in competitively binding the possible active metal sites, which may shield adsorption of oxygen species on those active metal sites, thus limiting ORR and/or OER activity. [54] The poisoning agents play a role in competitively binding the possible active metal sites, which may shield adsorption of oxygen species on those active metal sites, thus limiting ORR and/or OER activity.…”

Section: Further Discussion On Electrocatalytic Activity and Vital Romentioning

confidence: 99%

MO‐Co@N‐Doped Carbon (M = Zn or Co): Vital Roles of Inactive Zn and Highly Efficient Activity toward Oxygen Reduction/Evolution Reactions for Rechargeable Zn–Air Battery

Yin

Wang

et al. 2017

Adv Funct Materials

241

140

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A highly efficient bifunctional oxygen catalyst is required for practical applications of fuel cells and metal-air batteries, as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are their core electrode reactions. Here, the MO-Co@N-doped carbon (NC, M = Zn or Co) is developed as a highly active ORR/OER bifunctional catalyst via pyrolysis of a bimetal metal-organic framework containing Zn and Co, i.e., precursor (CoZn). The vital roles of inactive Zn in developing highly active bifunctional oxygen catalysts are unraveled. When the precursors include Zn, the surface contents of pyridinic N for ORR and the surface contents of Co-N x and Co 3+ /Co 2+ ratios for OER are enhanced, while the high specific surface areas, high porosity, and high electrochemical active surface areas are also achieved. Furthermore, the synergistic effects between Zn-based and Co-based species can promote the well growth of multiwalled carbon nanotubes (MWCNTs) at high pyrolysis temperatures (≥700 °C), which is favorable for charge transfer. The optimized CoZn-NC-700 shows the highly bifunctional ORR/OER activity and the excellent durability during the ORR/OER processes, even better than 20 wt% Pt/C (for ORR) and IrO 2 (for OER). CoZn-NC-700 also exhibits the prominent Znair battery performance and even outperforms the mixture of 20 wt% Pt/C and IrO 2 .

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“…However, these systems are known to be expensive and unstable, in particular, owing to their high sensitivity to poisoning. Other approaches to develop next‐generation reversible oxygen electrodes involve the combination of non‐precious single‐function ORR and OER catalysts into one hybrid system . For example, the introduction of ORR active M‐N x /C moieties into OER‐evolving perovskites to form efficient bifunctional ORR/OER catalysts was previously demonstrated .…”

Section: Introductionmentioning

confidence: 99%

“…Other approaches to develop next‐generation reversible oxygen electrodes involve the combination of non‐precious single‐function ORR and OER catalysts into one hybrid system . For example, the introduction of ORR active M‐N x /C moieties into OER‐evolving perovskites to form efficient bifunctional ORR/OER catalysts was previously demonstrated . Another example involved direct growth of N‐doped carbon nanostructures on the surface of OER‐active compounds, such as perovskites and borides by chemical vapor deposition (CVD) .…”

Section: Introductionmentioning

confidence: 99%

Bifunctional Oxygen Reduction/Oxygen Evolution Activity of Mixed Fe/Co Oxide Nanoparticles with Variable Fe/Co Ratios Supported on Multiwalled Carbon Nanotubes

et al. 2018

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A facile strategy is reported for the synthesis of Fe/Co mixed metal oxide nanoparticles supported on, and embedded inside, high purity oxidized multiwalled carbon nanotubes (MWCNTs) of narrow diameter distribution as effective bifunctional catalysts able to reversibly drive the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) in alkaline solutions. Variation of the Fe/Co ratio resulted in a pronounced trend in the bifunctional ORR/OER activity. Controlled synthesis and in-depth characterization enabled the identification of an optimal Fe/Co composition, which afforded a low OER/OER reversible overvoltage of only 0.831 V, taking the OER at 10 mA cm and the ORR at -1 mA cm . Importantly, the optimal catalyst with a Fe/Co ratio of 2:3 exhibited very promising long-term stability with no evident change in the potential for both the ORR and the OER after 400 charge/discharge (OER/ORR) cycles at 15 mA cm in 6 m KOH. Moreover, detailed investigation of the structure, size, and phase composition of the mixed Fe/Co oxide nanoparticles, as well as their localization (inside of or on the surface of the MWCNTs) revealed insight of the possible contribution of the individual catalyst components and their synergistic interaction in the catalysis.

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Activation of oxygen evolving perovskites for oxygen reduction by functionalization with Fe–N_x/C groups

Cited by 76 publications

References 27 publications

Nitrogen‐Doped Metal‐Free Carbon Materials Derived from Cellulose as Electrocatalysts for the Oxygen Reduction Reaction

Nitrogen‐Doped Metal‐Free Carbon Materials Derived from Cellulose as Electrocatalysts for the Oxygen Reduction Reaction

MO‐Co@N‐Doped Carbon (M = Zn or Co): Vital Roles of Inactive Zn and Highly Efficient Activity toward Oxygen Reduction/Evolution Reactions for Rechargeable Zn–Air Battery

Bifunctional Oxygen Reduction/Oxygen Evolution Activity of Mixed Fe/Co Oxide Nanoparticles with Variable Fe/Co Ratios Supported on Multiwalled Carbon Nanotubes

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Activation of oxygen evolving perovskites for oxygen reduction by functionalization with Fe–Nx/C groups

Cited by 76 publications

References 27 publications

Nitrogen‐Doped Metal‐Free Carbon Materials Derived from Cellulose as Electrocatalysts for the Oxygen Reduction Reaction

Nitrogen‐Doped Metal‐Free Carbon Materials Derived from Cellulose as Electrocatalysts for the Oxygen Reduction Reaction

MO‐Co@N‐Doped Carbon (M = Zn or Co): Vital Roles of Inactive Zn and Highly Efficient Activity toward Oxygen Reduction/Evolution Reactions for Rechargeable Zn–Air Battery

Bifunctional Oxygen Reduction/Oxygen Evolution Activity of Mixed Fe/Co Oxide Nanoparticles with Variable Fe/Co Ratios Supported on Multiwalled Carbon Nanotubes

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Activation of oxygen evolving perovskites for oxygen reduction by functionalization with Fe–N_x/C groups