Pyrolyzed M–N_x catalysts for oxygen reduction reaction: progress and prospects

Energy & Environmental Science, Journal Year: 2021, Volume and Issue: 14(4), P. 2158 - 2185

Published: Jan. 1, 2021

This review showcases the recent progress in understanding and designing M–N_x/C electrocatalysts towards ORR, aiming to provide some guidelines for their practical applications PEMFCs.

Language: Английский

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Atomic Fe–N₄/C in Flexible Carbon Fiber Membrane as Binder‐Free Air Cathode for Zn–Air Batteries with Stable Cycling over 1000 h

Advanced Materials, Journal Year: 2021, Volume and Issue: 34(5)

Published: Nov. 17, 2021

Noble-metal-free, durable, and high-efficiency electrocatalysts for oxygen reduction evolution reaction (ORR/OER) are vital rechargeable Zn-air batteries (ZABs). Herein, a flexible free-standing carbon fiber membrane immobilized with atomically dispersed Fe-N4 /C catalysts (Fe/SNCFs-NH3 ) is synthesized used as air cathode ZABs. The intertwined fibers hierarchical nanopores facilitate the gas transportation, electrolyte infiltration electron transfer. large specific surface area exposes high concentration of sites embedded in matrix. Modulation local atomic configurations by sulfur doping Fe/SNCFs-NH3 catalyst leads to excellent ORR enhanced OER activities. as-synthesized demonstrates positive half-wave potential 0.89 V small Tafel slope 70.82 mV dec-1 , outperforming commercial Pt/C (0.86 V/94.74 most reported M-Nx (M = Fe, Co, Ni) catalysts. Experimental characterizations theoretical calculations uncover crucial role S regulating liquid-state ZABs deliver peak power density 255.84 mW cm-2 long-term cycle durability over 1000 h. Solid-state ZAB shows stable cycling at various flat/bent/flat states, demonstrating great prospects electronic device applications.

Language: Английский

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Bridge Bonded Oxygen Ligands between Approximated FeN₄ Sites Confer Catalysts with High ORR Performance

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 59(33), P. 13923 - 13928

Published: May 21, 2020

The applications of the most promising Fe-N-C catalysts are prohibited by their limited intrinsic activities. Manipulating Fe energy level through anchoring electron-withdrawing ligands is found effective in boosting catalytic performance. However, such regulation remains elusive as only uncontrollably introduced oweing to energetically unstable nature. Herein, we report a rational manipulation strategy for introducing axial bonded O sites, attained hexa-coordinating with oxygen functional groups precursor. Moreover, modifier stabilized forming Fe-O-Fe bridge bond, approximation two FeN4 sites. modulation thus created confers sites an activity that over 10 times higher than normal site. Our finding opens novel manage coordination environments at atomic high ORR catalysts.

Language: Английский

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Understanding the Synergistic Effects of Cobalt Single Atoms and Small Nanoparticles: Enhancing Oxygen Reduction Reaction Catalytic Activity and Stability for Zinc‐Air Batteries

Advanced Functional Materials, Journal Year: 2021, Volume and Issue: 31(45)

Published: Aug. 8, 2021

Abstract The development of earth‐abundant oxygen reduction reaction (ORR) catalysts with high catalytic activity and good stability for practical metal‐air batteries remains an enormous challenge. Herein, a highly efficient durable ORR catalyst is reported, which consists atomically dispersed Co single atoms (Co‐SAs) in the form Co‐N4 moieties small nanoparticles (Co‐SNPs) co‐anchored on nitrogen‐doped porous carbon nanocage (Co‐SAs/SNPs@NC). Benefiting from synergistic effect Co‐SAs Co‐SNPs as well enhanced anticorrosion capability matrix brought by its improved graphitization degree, resultant Co‐SAs/SNPs@NC exhibits outstanding remarkable alkaline media, outperforming Co‐SAs‐based (Co‐SAs@NC), benchmark Pt/C catalyst. Density functional theory calculations reveal that strong interaction between sites can increase valence state active moderate adsorption free energy intermediates, thus facilitating O 2 . Moreover, zinc‐air battery assembled demonstrates maximum power density 223.5 mW cm –2 , specific capacity 742 W h kg –1 at 50 mA superior cycling stability.

Language: Английский

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What is the Real Origin of the Activity of Fe–N–C Electrocatalysts in the O₂ Reduction Reaction? Critical Roles of Coordinating Pyrrolic N and Axially Adsorbing Species

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(39), P. 18144 - 18152

Published: Sept. 22, 2022

Fe–N–C electrocatalysts have emerged as promising substitutes for Pt-based catalysts the oxygen reduction reaction (ORR). However, their real catalytic active site is still under debate. The underlying roles of different types coordinating N including pyridinic and pyrrolic in performance require thorough clarification. In addition, how to understand pH-dependent activity another urgent issue. Herein, we comprehensively studied 13 N-coordinated FeNxC configurations corresponding ORR through simulations which mimic realistic electrocatalytic environment on basis constant-potential implicit solvent models. We demonstrate that contributes a higher than N, FeN4C exhibits highest acidic media. Meanwhile, situ transformation *O-FeN4C *OH-FeN4C clarifies origin alkaline These findings can provide indispensable guidelines rational design better durable catalysts.

Language: Английский

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