Synergistic Effects between Atomically Dispersed Fe−N−C and C−S−C for the Oxygen Reduction Reaction in Acidic Media

Shen, Hong; Gracia‐Espino, Eduardo; Ma, Jingyuan; Zang, Ketao; Luo, Jun; Wang, Le; Gao, Sanshuang; Mamat, Xamxikamar; Hu, Guangzhi; Wågberg, Thomas; Guo, Shaojun

doi:10.1002/anie.201706602

Cited by 432 publications

(266 citation statements)

References 42 publications

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“…[1] In principal, the energy efficiency of rechargeable Zn-air batteries is primarily dominated by their oxygen electrocatalysts on air electrodes, where the oxygen evolution reaction( OER) and oxygen reduction reaction (ORR) alternatelyp roceed for charging and discharging, respectively.U nfortunately,a saresult of their multi-step fourelectron transfer properties, the ORR and OER processes suffer from extremely sluggish kinetics, which leads to very large potential gaps (> 0.85 V) and low energy efficiency for rechargeable Zn-air batteries. [3] However,t he high cost, scarcity,a nd poor stability of the Pt and Ir-based composite catalysts seriously inhibitt heir widespreadu tilization in rechargeable Zn-air batteries. [3] However,t he high cost, scarcity,a nd poor stability of the Pt and Ir-based composite catalysts seriously inhibitt heir widespreadu tilization in rechargeable Zn-air batteries.…”

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confidence: 99%

Cobalt‐Based Metal–Organic Framework Nanoarrays as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn‐Air Batteries

Chen

Zhang

Wang

et al. 2018

Chemistry A European J

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Owing to their high theoretical energy density, environmental benign character, and low cost, rechargeable Zn-air batteries have emerged as an attractive energy technology. Unfortunately, their energy efficiency is seriously plagued by sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) that alternately occurs on air electrodes. Herein, we demonstrate Co-based metal-organic framework (Co(bpdc)(H O) (bpdc=biphenyl -4, 4'-dicarboxylic acid), Co-MOF) arrays as novel bifunctional oxygen electrocatalysts. The Co-MOF is in situ constructed on a three-dimensional graphite foam (GF) through a hydrothermal reaction. In a 1 m KOH aqueous solution, the resultant Co-MOF/GF exhibits an OER overpotential of only ≈220 mV at 10 mA cm , which is much lower than those for Ir/C and previously reported noble metal-free electrocatalysts. In conjunction with its ORR half-wave potential of 0.7 V (vs. RHE), the Co-MOF/GF manifests a greatly decreased potential gap of ≈0.75 V in comparison with Pt/C-Ir/C couple and previously reported bifunctional oxygen electrocatalysts. Furthermore, an assembled rechargeable zinc-air battery using Co-MOF electrocatalyst in an air electrode delivers a maximum power density of 86.2 mW cm and superior charge-discharge performance. Microscopic, spectroscopic and electrochemical analyses prove that the initial Co-MOF is transformed into Co-oxyhydroxides during the OER and ORR process, which essentially serve as bifunctional active centers.

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mentioning

confidence: 99%

Cobalt‐Based Metal–Organic Framework Nanoarrays as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn‐Air Batteries

Chen

Zhang

Wang

et al. 2018

Chemistry A European J

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“…Concurrently, a vital aspect for single or few‐atom motifs to improve the ORR efficiency is to obtain a structural design of the catalysts that enhances the selectivity toward 4e − reduction of O 2 by suppressing the production of H 2 O 2 . It has been shown that under alkaline solutions, the Lewis acidic Fe 2+ active sites can efficiently adsorb and immediately reduce the Lewis basic HO 2 − intermediates through a 4e − process . However in very strong alkaline electrolytes, the active sites from the iron center are fully covered by adsorbed hydroxy species in the inner Helmholtz plane and the solvated O 2 is localized in the outer Helmholtz plane .…”

Section: Iron‐based Electrocatalystsmentioning

confidence: 99%

“…Accordingly, in recent years, there has been an increasing attention devoted to downsizing the transition metal particles into clusters or ultimately into single atoms supported in matrixes consisting of non‐noble‐metal materials . Such single‐ or few‐atom motifs embedded in a conductive matrix have the potential to both deliver a low overpotential at each active site and concurrently be present in large quantities to provide an overall high turnover number and thus a high current density at low potential.…”

Section: Introductionmentioning

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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“…[14] Compared with bulk metal catalysts,a tomically dispersed metal or metal-doped carbon possesses distinct electronic structure and fully exposed active sites,r endering catalytic reactions better reactivity and selectivity. [14] Compared with bulk metal catalysts,a tomically dispersed metal or metal-doped carbon possesses distinct electronic structure and fully exposed active sites,r endering catalytic reactions better reactivity and selectivity.…”

Section: Zuschriftenmentioning

confidence: 99%

From Supramolecular Species to Self‐Templated Porous Carbon and Metal‐Doped Carbon for Oxygen Reduction Reaction Catalysts

Xie

Peng

et al. 2019

Angewandte Chemie

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The preparation of carbon materials usually involves the decomposition of precursors and the reorganization of the as-generated fragments.H owever,t he cleavage of bonds and the simultaneous formation of new bonds at nearly the same positions prevents effective yet precise fabrication. Herein, as upramolecular precursor,c ucurbit[6]uril, that contains multiple bonds with distinct bond strengths is proposed to decouple the twin problem of simultaneous bond cleavage and formation, allowing multistage transformations to hierarchical porous carbon and metal-doped carbon in as ingle yet effective pyrolysis step without the need of at emplate or additional purification. As ap roof-of-concept, the Fe-doped carbon electrocatalysts realized aPt/C-like halfwave potential of 0.869 Vv s. RHE and small Tafel slope of 51.3 mV dec À1 in oxygen reduction reaction.Carbon materials is ab road family of easily accessible yet structurally tunable materials that have been widely employed in various applications,s uch as energy storage, adsorption, and catalysis. [1] Enormous efforts have been dedicated to their controllable synthesis toward specific structures and properties,that is,porosity and conductivity. [2] Among the preparation methods,t he precursor pyrolysis approach gains the most attention owing to its simplicity and tunability. [3] Generally,t his synthetic method involves the decomposition of precursors and the reorganization of asgenerated fragments,c oncretely,t he cleavage of CÀC/CÀH/ CÀX(Xrepresents anonmetal element) bonds and formation of new bonds (mainly sp 2 CÀCbonds for graphitic carbon). [4] However,t he bond cleavage/formation commonly occurs at nearly the same rate and position because of the comparable bond strengths.The simultaneous bond breaking and rebuilding always induces drastic local changes in structure and heat, resulting structural collapse of pyrolytic intermediates and final products,a sw ell as loss of desirable features and properties (such as,high surface area, large pore volume,and heteroatom dopants). [5] Va rious hard and soft templates were designed to stabilize the intermediates and control the final product structure. [6] However, the cost of these templates and complicated multistep fabrication including template removal always remain ap roblem for applications.H ence,i ti s promising to develop template-free or self-templated methods toward new carbon materials and of fundamental interest to decipher the related pyrolysis mechanism. [7] From amolecular perspective,the template-free synthesis of carbon materials relies on decoupling the twin problem of spatio-temporally identical bond cleavage and formation. In this regard, extra bonds were designed in precursors through either small-molecule crosslinking or backbone conjugation to form ar igid precursor framework. [8] Nevertheless,t hese attempts resulted in mostly microporous carbon that hardly contains mesopores owing to the short distance between these rigid conjunctions.I fl ong-range interactions with bond strengths dist...

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Synergistic Effects between Atomically Dispersed Fe−N−C and C−S−C for the Oxygen Reduction Reaction in Acidic Media

Cited by 432 publications

References 42 publications

Cobalt‐Based Metal–Organic Framework Nanoarrays as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn‐Air Batteries

Cobalt‐Based Metal–Organic Framework Nanoarrays as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn‐Air Batteries

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

From Supramolecular Species to Self‐Templated Porous Carbon and Metal‐Doped Carbon for Oxygen Reduction Reaction Catalysts

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