scholarly journals Atomically Dispersed Fe-N4 Modified with Precisely Located S for Highly Efficient Oxygen Reduction

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yin Jia ◽  
Xuya Xiong ◽  
Danni Wang ◽  
Xinxuan Duan ◽  
Kai Sun ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Density Functional ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Edge Structure ◽  
Onset Potential ◽  
Local Environments ◽  
Half Wave ◽  
Reaction Performance ◽  
Specific Configuration

AbstractImmobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N3)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N4 moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N4 moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-Nx moiety.

scholarly journals Fluorine-doped graphene with an outstanding electrocatalytic performance for efficient oxygen reduction reaction in alkaline solution

2018 ◽  
Vol 5 (10) ◽  
pp. 180925 ◽  
Author(s):  
Jiahao Guo ◽  
Jianguo Zhang ◽  
Hanqing Zhao ◽  
Yongshuang Fang ◽  
Kun Ming ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Carbon Materials ◽  
Pyrolysis Temperature ◽  
Low Cost ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Onset Potential ◽  
Doped Graphene ◽  
Cost Efficient

Doping carbon materials have proved to be the front runners to substitute for Pt as oxygen reduction reaction (ORR) catalysts. Fluorine-doped graphene (FG) has rarely been used as ORR catalyst because of the difficulty in preparation. Herein, we report FG sheets prepared by a thermal pyrolysis graphene oxide (GO) process in the presence of zinc fluoride (ZnF 2 ) as an efficient electrocatalyst for ORR in the alkaline medium. The results show that the pyrolysis temperature seriously affected the doped fluoride amount and morphology of catalyst. It is found that the FG-1100 catalyst possesses a more positive onset potential, higher current density and better four-electron process for ORR than other FG samples. FG-1100 displays an outstanding ORR catalytic activity that is comparable to that of the commercial Pt/C catalyst. Also, its durability and methanol tolerance ability are superior to those of the commercial Pt/C. The excellent ORR catalytic performance is closely related to its higher doped fluorine amount and wrinkle morphology. The FG catalyst can be developed as a low-cost, efficient and durable catalyst as a viable replacement for the Pt/C catalyst, promoting the commercialization of fuel cells.

scholarly journals 2,2’-Dipyridylamine as Heterogeneous Organic Molecular Electrocatalyst for Two-Electron Oxygen Reduction Reaction in Acid Media

2019 ◽  
Author(s):  
Xi Yin ◽  
Ling Lin ◽  
Ulises Martinez ◽  
Piotr Zelenay
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
High Activity ◽  
Density Functional ◽  
Continuous Production ◽  
Reduction Reaction ◽  
Pulp Bleaching ◽  
Acid Media ◽  
Onset Potential ◽  
Production Of Hydrogen

Continuous production of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) through the two-electron oxygen reduction reaction (2e-ORR) in distributed electrochemical cells offers important advantages for point-of-use water treatment and pulp bleaching over the complex industrial anthraquinone process. A low-cost, heterogeneous 2e-ORR electrocatalyst with high activity and selectivity is key to meeting the future needs for distributed production of H<sub>2</sub>O<sub>2</sub> with large capacity. Herein, we demonstrate high activity and selectivity of a new heterogeneous organic molecular electrocatalyst, 2,2’-dipyridylamine, with an H<sub>2</sub>O<sub>2</sub> yield of <i>ca.</i> 80%, and an onset potential of <i>ca.</i> 0.60 V <i>vs.</i> RHE in acidic aqueous electrolyte. We show that this acid-compatible, inexpensive, small organic molecule can catalyze 2e-ORR as efficiently as the state-of-the-art catalysts based on mercury-precious metal alloys. We propose different mechanisms of dioxygen electroreduction based on density functional theory calculations, which correlate activity with calculated standard reduction potential of reaction intermediates.

scholarly journals Heteroatom-doped hollow carbon material as an electrocatalyst for oxygen reduction reaction

2021 ◽  
Vol 2079 (1) ◽  
pp. 012007
Author(s):  
Tiantian Sun ◽  
Heng-guo Wang
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Carbon Materials ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Carbon Nanospheres ◽  
Diffusion Limited ◽  
Half Wave ◽  
Phosphorus Containing ◽  
Hollow Carbon

Abstract The development of highly efficient and stable non-precious metal electrocatalysts is essential for the oxygen reduction reaction (ORR). In this study, a simple polymerization pyrolysis method is proposed to prepare heteroatom-doped hollow carbon nanospheres (NPSC-800) by using Fe-BDC and phosphorus-containing polymers as precursors. The unique structure allows the catalyst to show good catalytic performance (Initial potential of 0.8786 V, a half-wave potential of 0.7576 V, and a diffusion-limited current density of 4.48 mA cm-2). This research provides an effective strategy for the synthesis of heteroatom-doped carbon materials with good ORR catalytic performance.

2,2’-Dipyridylamine as Heterogeneous Organic Molecular Electrocatalyst for Two-Electron Oxygen Reduction Reaction in Acid Media

2019 ◽  
Author(s):  
Xi Yin ◽  
Ling Lin ◽  
Ulises Martinez ◽  
Piotr Zelenay
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
High Activity ◽  
Density Functional ◽  
Continuous Production ◽  
Reduction Reaction ◽  
Pulp Bleaching ◽  
Acid Media ◽  
Onset Potential ◽  
Production Of Hydrogen

Continuous production of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) through the two-electron oxygen reduction reaction (2e-ORR) in distributed electrochemical cells offers important advantages for point-of-use water treatment and pulp bleaching over the complex industrial anthraquinone process. A low-cost, heterogeneous 2e-ORR electrocatalyst with high activity and selectivity is key to meeting the future needs for distributed production of H<sub>2</sub>O<sub>2</sub> with large capacity. Herein, we demonstrate high activity and selectivity of a new heterogeneous organic molecular electrocatalyst, 2,2’-dipyridylamine, with an H<sub>2</sub>O<sub>2</sub> yield of <i>ca.</i> 80%, and an onset potential of <i>ca.</i> 0.60 V <i>vs.</i> RHE in acidic aqueous electrolyte. We show that this acid-compatible, inexpensive, small organic molecule can catalyze 2e-ORR as efficiently as the state-of-the-art catalysts based on mercury-precious metal alloys. We propose different mechanisms of dioxygen electroreduction based on density functional theory calculations, which correlate activity with calculated standard reduction potential of reaction intermediates.

Bimetallic ZIF derived Co nanoparticle anchored N-doped porous carbons for an efficient oxygen reduction reaction

2020 ◽  
Vol 7 (4) ◽  
pp. 946-952 ◽  
Author(s):  
Kaili Li ◽  
Daohao Li ◽  
Liangkui Zhu ◽  
Zhuangzhuang Gao ◽  
Qianrong Fang ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
High Performance ◽  
Reduction Reaction ◽  
Porous Carbons ◽  
Wave Potential ◽  
Half Wave Potential ◽  
Half Wave ◽  
Reaction Performance

A high-performance electrocatalytic material was derived from a new bimetallic ZIF precursor, exhibiting excellent oxygen reduction reaction performance with a half-wave potential (E1/2) of 0.849 V, superior to that of commercial Pt/C.

scholarly journals Nitrogen and sulfur co-doping of partially exfoliated MWCNTs as 3-D structured electrocatalysts for the oxygen reduction reaction

2016 ◽  
Vol 4 (15) ◽  
pp. 5678-5684 ◽  
Author(s):  
Jie Wang ◽  
Zexing Wu ◽  
Lili Han ◽  
Ruoqian Lin ◽  
Weiping Xiao ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Co Doping ◽  
Heat Treated ◽  
Half Wave ◽  
Temperature Heat ◽  
Excellent Catalytic Performance

Nitrogen and sulfur co-doping of graphene nanoribbon/CNT composites is obtained by using high temperature heat-treated thiourea with partially unzipped MWCNTs which exhibit excellent catalytic performance for the ORR with similar onset and half-wave potentials as Pt/C.

scholarly journals An ultra-dispersive, nonprecious metal MOF–FeZn catalyst with good oxygen reduction activity and favorable stability in acid

2021 ◽  
Vol 56 (14) ◽  
pp. 8600-8612
Author(s):  
Qing Zhao ◽  
Cheng Wang ◽  
Haifeng Wang ◽  
Jianlong Wang
Keyword(s):  
Oxygen Reduction ◽  
High Performance ◽  
Reduction Reaction ◽  
Graphitic Carbon ◽  
Potential Cycling ◽  
Onset Potential ◽  
Wave Potential ◽  
Reduction Activity ◽  
Half Wave Potential ◽  
Half Wave

AbstractDevelopment of the more stable nonprecious oxygen reduction reaction (ORR) catalyst is of great significance nowadays. Herein, a high-performance iron-doped integral uniform macrocyclic organic framework (MOF–FeZn) catalyst is synthesized through a combined hydrothermal and pyrolysis process, showing favorable ORR activity and stability in acid. This as-synthesized MOF–FeZn catalyst displays high porous and graphitic structures with sufficient catalytic active dopants of pyridinic N, Fe–N, pyrrolic N, graphitic N, making it a promising ORR candidate catalyst with high electrochemical stability. The onset potential, half-wave potential and limited diffusion current density of MOF–FeZn are 0.93 V @ 0.1 mA cm−2, 0.768 V@ 2.757 mA cm−2 and 5.5 mA cm−2, respectively, which are comparable to the state-of-the-art nonprecious catalyst and commercial Pt/C. ORR catalysis on MOF–FeZn follows the nearly four-electron path. What is more, MOF–FeZn can sustain the 10,000 cycles electrochemical potential cycling process in acid with the half-wave potential changed only 21 mV, superior to the reduction of 149 mV for Pt/C. The well-developed integral uniform structures, homogeneously dispersed carbides and nitrides protected by the highly graphitic carbon layers and the better agglomeration suppression of nanoparticles by the confined graphitic carbon layers on catalyst can significantly enhance the catalytic activity and stability of MOF–FeZn.

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

scholarly journals Electrocatalysis for Oxygen Reduction Reaction on EDTAFeNa and Melamine co-Derived Self-Supported Fe-N-C Materials

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 623
Author(s):  
Mengfan Shen ◽  
Ziwei Meng ◽  
Tong Xue ◽  
Hongfang Shen ◽  
Xiang-Hui Yan
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Large Scale ◽  
Acid Leaching ◽  
Reduction Reaction ◽  
Scale Production ◽  
Final Annealing ◽  
High Performing ◽  
Half Wave ◽  
Mesoscopic Structure

To explore high-performing alternatives to platinum-based catalysts is highly desirable for lowering costs and thus promoting fuel cell commercialization. Herein, self-supported Fe-N-C materials were prepared by the pyrolysis of dual precursors including EDTA ferric sodium (EDTAFeNa) and melamine (MA), followed by acid-leaching and final annealing. Towards an oxygen reduction reaction (ORR) in 0.1 M KOH, the as-prepared MA/EDTAFeNa-HT2 delivered onset (Eonset) and half-wave (E1/2) potentials of 0.97 and 0.84 V vs. RHE, respectively, identical with that of a state-of-the-art Pt/C catalyst, accompanied with predominantly a four-electron pathway. The introduction of MA and extension of acid-leaching promoted a positive shift of 50 mV for E1/2 relative to that of only the EDTAFeNa-derived counterpart. It was revealed that the enhancement of ORR activity is attributed to a decrease in magnetic Fe species and increase in pyridinic/quanternary nitrogen content whilst nearly excluding effects of the graphitization degree, variety of crystalline iron species, and mesoscopic structure. The usage of dual precursors exhibited great potential for the large-scale production of inexpensive and efficient Fe-N-C materials.

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