Boosting the oxygen reduction activity of a three-dimensional network Co–N–C electrocatalyst <i>via</i> space-confined control of nitrogen-doping efficiency and the molecular-level coordination effect

Guo, Chaozhong; Li, Yanrong; Liao, Wenli; Liu, Yao; Li, Zhongbin; Sun, Lingtao; Chen, Changguo; Zhang, Jin; Si, Yujun; Li, Lü

doi:10.1039/c8ta03759k

Cited by 77 publications

(43 citation statements)

References 34 publications

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“…The existence of CoO can be ascribed to the oxide of surface structure, which is consistent with the TEM‐EDS analyses. Furthermore, the N 1s XPS spectrum in Figure d was deconvoluted into four types of nitrogen species located at 398.0, 399.1, 400.3, and 405.1 eV, respectively, corresponding to pyridinic‐N, CoN, graphitic−N, and oxidized NO, further demonstrating the formation of Co–N–C nanostructures in Co/Co–N–C . The Co−N bond can be equally associated with the Co–N–C functional moieties.…”

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confidence: 92%

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Co Nanoislands Rooted on Co–N–C Nanosheets as Efficient Oxygen Electrocatalyst for Zn–Air Batteries

et al. 2019

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been devoted to various energy storage and conversion systems. [1,2] Metal-air batteries, especially Zn-air batteries (ZABs) have been regarded as a promising energy storage system due to their low-cost, high theoretical specific energy density (1084 Wh kg −1 ), and environmental friendliness. [3][4][5] Nevertheless, the multistep and proton-coupled electron transfer processes of the reversible oxygen reactions lead to sluggish kinetics for oxygen reduction (ORR) and oxygen evolution (OER) at aircathode, which are the bottlenecks of inefficient and unideal lifetime. [6] The current benchmark catalysts for simply ORR or OER are precious-metal-based catalysts (Pt, Ir, RuO 2 , etc.), but their high cost, supply scarcity, and poor bifunctional catalytic characters have greatly restricted their applications in ZABs. [7,8] In response, various transition-based catalysts with high activity and good durability have been explored, such as transition metal oxides, chalcogenides, and metal-heteroatom doped carbon materials. [9][10][11][12][13][14] Despite significant progress, current bifunctional catalysts are still facing the problems of insufficient activity and stability together with poor mass transport properties.Alternatively, metal-nitrogen-carbon (M-N-C) systems comprising the earth abundant transition metals and catalytic active metalN x centers with carbonized ligand have received growing interest due to their low cost and excellent catalytic activities. [15][16][17] Specially, Co-N-C has emerged as ORR catalyst for improvement the overall performance of ZABs. [18,19] Inspired by the excellent OER performance of Co-based catalysts (e.g., cobalt metal and cobalt oxide) and intrinsically electrical conductivity of Co metal, [20,21] so constructing hierarchical structure of Co-N-C contained Co metal maybe an effective way to promote the bifunctional ORR/OER activity. At present, various strategies have been applied to synthesize Co-N-C structures. Traditionally, carbonized the Co-based precursors (such as porphyrins and phthalocyanines) have been developed for several decades to synthesize metal contained N-doped carbon nanostructures, [22,23] but always suffer from large nanoparticles size and ununiformed structures. Hence, much efforts have been devoted to construct Co-N-C-based catalysts with novel morphology and structures, such as core-shell or single-atom dispersed Co-N-C catalysts combined with carbon nanotubes Developing non-precious-metal bifunctional oxygen reduction and evolution reaction (ORR/OER) catalysts is a major task for promoting the reaction efficiency of Zn-air batteries. Co-based catalysts have been regarded as promising ORR and OER catalysts owing to the multivalence characteristic of cobalt element. Herein, the synthesis of Co nanoislands rooted on Co-N-C nanosheets supported by carbon felts (Co/Co-N-C) is reported. Co nanosheets rooted on the carbon felt derived from electrodeposition are applied as the self-template and cobalt source. The synergistic effect of metal Co islands with OER a...

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confidence: 92%

“…Alternatively, metal–nitrogen–carbon (M–N–C) systems comprising the earth abundant transition metals and catalytic active metalN x centers with carbonized ligand have received growing interest due to their low cost and excellent catalytic activities . Specially, Co–N–C has emerged as ORR catalyst for improvement the overall performance of ZABs .…”

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confidence: 99%

Co Nanoislands Rooted on Co–N–C Nanosheets as Efficient Oxygen Electrocatalyst for Zn–Air Batteries

et al. 2019

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“…1 A schematic drawing for the synthesis of mesoporous Fe/N/C catalysts of a rotation ring (Pt)-disk (glassy carbon, Φ = 5 mm) working electrode (RRDE, American Pine Instrument Co., Ltd.), a saturated calomel reference electrode (SCE) and a Pt-foil counter electrode (1 cm 2 ). The preparation of the catalyst-coated RRDE refers to the previous reports [21,25]. Generally, 10 μl of 10 mg ml −1 catalyst dispersion was dropped onto RRDE and naturally dried.…”

Section: Electrochemical Testsmentioning

confidence: 99%

“…One of concern is that the fabrication of Fe/N/C catalysts from direct carbonization of macromolecule polymers [12,19,20], chemical complexes and biological proteins containing Fe-N x structures [15,21,22], and other iron-nitrogen sources [17,23,24] is commonly carried out in an open system. Besides, most of nitrogen-enriched precursors may be easy to occur at accumulation or agglomeration in carbonization process, which will prevent effective exposure of catalytically ORR active sites, promote the thermal loss of N atoms, and reduce the active-site density, resulting in the limitation of the ORR performance of Fe/N/C catalysts [25]. Another concern is that the electronic conductivity of the synthesized Fe/N/C materials also determines their ORR activity.…”

Section: Introductionmentioning

confidence: 99%

“…Several research groups proposed some effective confined reaction strategies to improve this phenomenon. Some typical samples are as follows: (i) the montmorillonite with a confined interlayer space of~1 nm is used as a 2D space-confined reactor to avoid the packing and the thermal loss of active nitrogen atoms and increase the conductance characteristics [26], (i) the supersaturated sodium chlorides are emerged as a totally enclosed reactor to control the nitrogen loss and increase the active site density [27], and (iii) our group recently used self-assembled 3D-NaCl aggregates as a semi-closed confined-reactor to effectively decrease the decomposition speed of active nitrogen-rich structures, leading to the increasing of the active-site density and the enhancement of the ORR activity [25]. However, these methods commonly need cumbersome pretreatment, complicate technology or limited resistance to the over-high temperature.…”

Section: Introductionmentioning

confidence: 99%

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Nanochannel-Controlled Synthesis of Ultrahigh Nitrogen-Doping Efficiency on Mesoporous Fe/N/C Catalysts for Oxygen Reduction Reaction

Guo

et al. 2020

Nanoscale Res Lett

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Designing appropriate methods to effectively enhance nitrogen-doping efficiency and active-site density is essential to boost the oxygen reduction reaction (ORR) activity of non-platinum Fe/N/C-type electrocatalysts. Here, we propose a facile and effective strategy to design a mesopore-structured Fe/N/C catalyst for the ORR with ultrahigh BET surface area and outstanding conductivity via nanochannels of molecular sieve-confined pyrolysis of Fe 2+ ions coordinated with 2,4,6-tri(2-pyridyl)-1,3,5-triazine complexes as a novel precursor with the stable coordination effect. Combining the nanochannel-confined effect with the stable coordination effect can synergistically improve the thermal stability and stabilize the nitrogen-enriched active sites, and help to control the loss of active N atoms during pyrolysis process and to further obtain a high active-site density for enhancing the ORR activity. The asprepared Fe/N/C electrocatalyst has exhibited excellent catalytic activity with an onset potential of~0.841 V (versus RHE) closely approaching the Pt/C catalyst and high long-term stability in alkaline electrolyte. Besides, low-hydrogen peroxide yield (< 6.5%) and high electron transfer number (3.88-3.94) can be found on this catalyst, indicating that it is a valuable substitute for traditional Pt/C catalysts. This work paves a new way to design high-performance Fe/ N/C electrocatalysts and deepens the understanding of active site and ORR catalysis mechanism.

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Emerging Metal Single Atoms in Electrocatalysts and Batteries

Zhu

Wang

et al. 2020

Adv Funct Materials

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Energy conversion and storage applications require highly stable and efficient electrocatalysts/electrodes to facilitate electrochemical reactions, but these materials commonly suffer from serious atom wastes and lower performances than the theoretical levels, which cannot meet the increasing demands of the green atomic economy, thereby limiting their practical applications. Recently, metal single atoms (SAs) have attracted tremendous attention owing to their merits of full atom utilization, unique electronic structures, tunable surface characteristics, and low costs. However, metal SAs usually have relatively low physical/chemical stabilities due to their high surface energy, which results in severe degradation of electrochemical performances. Novel synthetic strategies are developed for metal SAs with better stability and performance. In this review, these strategies will be introduced in the context of electrocatalysis and batteries. Specifically, the design concepts, synthesis approach properties, and applications of metal SAs will be discussed. Finally, the critical challenges and future perspectives of metal SAs are presented. This review aims to provide new insights for future work as well as the real-world applications of metal SAs.

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Boosting the oxygen reduction activity of a three-dimensional network Co–N–C electrocatalyst via space-confined control of nitrogen-doping efficiency and the molecular-level coordination effect

Abstract: Self-assembled 3D-NaCl aggregates are used to boost the ORR activity of Co–N–C catalysts.

Cited by 77 publications

References 34 publications

Co Nanoislands Rooted on Co–N–C Nanosheets as Efficient Oxygen Electrocatalyst for Zn–Air Batteries

Co Nanoislands Rooted on Co–N–C Nanosheets as Efficient Oxygen Electrocatalyst for Zn–Air Batteries

Nanochannel-Controlled Synthesis of Ultrahigh Nitrogen-Doping Efficiency on Mesoporous Fe/N/C Catalysts for Oxygen Reduction Reaction

Emerging Metal Single Atoms in Electrocatalysts and Batteries

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