Simple combination of a protic salt and an iron halide: precursor for a Fe, N and S co-doped catalyst for the oxygen reduction reaction in alkaline and acidic media

Hoque, Mahfuzul; Zhang, Shiguo; Thomas, Morgan L.; Li, Zhe; Suzuki, Soma; Ando, Ayumi; Yanagi, Masato; Kobayashi, Yoshio; Dokko, Kaoru; Watanabe, Masayoshi

doi:10.1039/c7ta09975d

Cited by 31 publications

(12 citation statements)

References 96 publications

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“…As shown in Figure 4a, FeSA/HNPC demonstrates a higher retention of E 1/2 after 5000 cycles in contrast to Pt/C. The slight loss of E 1/2 (11 mV) for FeSA/HNPC might result from the attack of H 2 O 2 species (HO 2 − in alkaline) [52] . Apart from that, the severe aggregations of iron‐based NPs after long‐term durability test (Figure S12) decreases the active site densities, thus resulting in a lower ORR performance in Figure 4a.…”

Section: Resultsmentioning

confidence: 95%

A Highly Efficient Fe−N−C Electrocatalyst with Atomically Dispersed FeN₄ Sites for the Oxygen Reduction Reaction

Jin

Xie

et al. 2021

ChemCatChem

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Atomically dispersed Fe−N−C electrocatalysts have displayed excellent catalytic performances towards the oxygen reduction reaction (ORR), while the identification of the genuine active sites remains a challenge. Herein, we report a Fe−N−C electrocatalyst of FeSA/HNPC featuring single‐atomic FeN4 sites on hierarchically N‐doped porous carbon (HNPC), which shows a very competitive ORR activity in alkaline solution even at a low electrocatalyst loading of 0.2 mg cm−2 on the working electrode. A comparison of energy barriers in ORR reveals that the single‐atomic FeN4 active sites in FeSA/HNPC existing in the form of pyrrole‐N4−Fe is more favorable than that of pyridine‐N4−Fe for the enhanced ORR activity. Understanding the nature of FeN4 active sites will greatly benefit the design of Fe−N−C electrocatalysts with highly effective ORR performances.

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Section: Resultsmentioning

confidence: 95%

A Highly Efficient Fe−N−C Electrocatalyst with Atomically Dispersed FeN₄ Sites for the Oxygen Reduction Reaction

Jin

Xie

et al. 2021

ChemCatChem

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“…It has also been shown that protonation of sulfur is not as severe as that of nitrogen, and thus S‐species can be used to significantly improve the ORR efficiency of the active site due to a synergistic effect as shown by Shen et al Chen et al presented an efficient strategy to achieve atomically dispersed Fe–N x on N, S codecorated hierarchical carbon layers by coating carbon nanotubes (CNTs) with 2,2‐bipyridine and Fe salt precursor . By a similar strategy, Hoque et al realized in situ formation of FeN bonds in the N, S codoped carbons via the suitability of the precursors and silica template . Mesoporous architecture and in situ formation is also an effective method to improve the efficiency and durability of Fe–S based catalysts.…”

Section: Iron‐based Electrocatalystsmentioning

confidence: 99%

Oxygen Reduction Reactions on Single‐ or Few‐Atom Discrete Active Sites for Heterogeneous Catalysis

Sharifi

Gracia‐Espino

Chen

et al. 2019

Advanced Energy Materials

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The oxygen reduction reaction (ORR) is of great importance in energy‐converting processes such as fuel cells and in metal–air batteries and is vital to facilitate the transition toward a nonfossil dependent society. The ORR has been associated with expensive noble metal catalysts that facilitate the O2 adsorption, dissociation, and subsequent electron transfer. Single‐ or few‐atom motifs based on earth‐abundant transition metals, such as Fe, Co, and Mo, combined with nonmetallic elements, such as P, S, and N, embedded in a carbon‐based matrix represent one of the most promising alternatives. Often these are referred to as single atom catalysts; however, the coordination number of the metal atom as well as the type and nearest neighbor configuration has a strong influence on the function of the active sites, and a more adequate term to describe them is metal‐coordinated motifs. Despite intense research, their function and catalytic mechanism still puzzle researchers. They are not molecular systems with discrete energy states; neither can they fully be described by theories that are adapted for heterogeneous bulk catalysts. Here, recent results on single‐ and few‐atom electrocatalyst motifs are reviewed with an emphasis on reports discussing the function and the mechanism of the active sites.

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“…It is reported that the presence of sulfur-based species can enhance the ORR performance of Fe/N/C catalysts by decreasing the generation of intermediate H 2 O 2 . However, there are a number of reports which concentrate on the heteroatom-doped Fe/N/C electrocatalysts, and most of them are investigating the ORR performance in alkaline solutions (Hoque et al, 2018;You et al, 2018;Wu et al, 2019;Zheng et al, 2019). Therefore, it is necessary to develop heteroatom-doped catalysts with high electrochemical performance in acidic medium, which so far is more practical for fuel cells.…”

Section: Introductionmentioning

confidence: 99%

Novel Heteroatom-Doped Fe/N/C Electrocatalysts With Superior Activities for Oxygen Reduction Reaction in Both Acid and Alkaline Solutions

et al. 2020

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The exploration of noble metal-free catalysts with efficient electrochemical performance toward oxygen reduction reaction in the acid electrolyte is very important for the development of fuel cells technology. Novel pyrolyzed heteroatom-doped Fe/N/C catalysts have been regarded as the most efficient electrocatalytic materials for ORR due to their tunable electronic structure, and distinctive chemical and physical properties. Herein, nitrogen-and sulfur-doped (Fe/N/C and Fe/N/C-S) electrocatalysts were synthesized using ferric chloride hexahydrate as the Fe precursor, N-rich polymer as N precursor, and Ketjen Black EC-600 (KJ600) as the carbon supports. Among these electrocatalysts, the as prepared S and N-doped Fe/N/C-S reveals the paramount ORR activity with a positive half-wave potential value (E 1/2 ) 0.82 at 0.80 V vs. RHE in 0.1 mol/L H 2 SO 4 solution, which is comparable to the commercial Pt/C (Pt 20 wt%) electrocatalyst. The mass activity of the Fe/N/C-S catalyst can reach 45% (12.7 A g −1 at 0.8 V) and 70% (5.3 A g −1 at 0.95 V) of the Pt/C electrocatalyst in acidic and alkaline solutions. As result, ORR activity of PGM-free electrocatalysts measured by the rotating-ring disk electrode method increases in the following order: Fe/N/C

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Simple combination of a protic salt and an iron halide: precursor for a Fe, N and S co-doped catalyst for the oxygen reduction reaction in alkaline and acidic media

Abstract: A simple and robust strategy for an Fe based oxygen reduction catalyst using a protic salt and an iron halide.

Cited by 31 publications

References 96 publications

A Highly Efficient Fe−N−C Electrocatalyst with Atomically Dispersed FeN₄ Sites for the Oxygen Reduction Reaction

A Highly Efficient Fe−N−C Electrocatalyst with Atomically Dispersed FeN₄ Sites for the Oxygen Reduction Reaction

Oxygen Reduction Reactions on Single‐ or Few‐Atom Discrete Active Sites for Heterogeneous Catalysis

Novel Heteroatom-Doped Fe/N/C Electrocatalysts With Superior Activities for Oxygen Reduction Reaction in Both Acid and Alkaline Solutions

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Simple combination of a protic salt and an iron halide: precursor for a Fe, N and S co-doped catalyst for the oxygen reduction reaction in alkaline and acidic media

Abstract: A simple and robust strategy for an Fe based oxygen reduction catalyst using a protic salt and an iron halide.

Cited by 31 publications

References 96 publications

A Highly Efficient Fe−N−C Electrocatalyst with Atomically Dispersed FeN4 Sites for the Oxygen Reduction Reaction

A Highly Efficient Fe−N−C Electrocatalyst with Atomically Dispersed FeN4 Sites for the Oxygen Reduction Reaction

Oxygen Reduction Reactions on Single‐ or Few‐Atom Discrete Active Sites for Heterogeneous Catalysis

Novel Heteroatom-Doped Fe/N/C Electrocatalysts With Superior Activities for Oxygen Reduction Reaction in Both Acid and Alkaline Solutions

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Product

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A Highly Efficient Fe−N−C Electrocatalyst with Atomically Dispersed FeN₄ Sites for the Oxygen Reduction Reaction

A Highly Efficient Fe−N−C Electrocatalyst with Atomically Dispersed FeN₄ Sites for the Oxygen Reduction Reaction