Electrocatalytic Ammonia Oxidation Mediated by a Polypyridyl Iron Catalyst

doi:10.1021/acscatal.9b03499

Title: Electrocatalytic Ammonia Oxidation Mediated by a Polypyridyl Iron Catalyst

Abstract

Electrocatalytic ammonia oxidation (AO) mediated by iron(II) tris(2-pyridylmethyl)amine (TPA) bis-ammine triflate, [(TPA)Fe(NH₃)₂]OTf₂, is reported. Interest in (electro)catalytic AO is growing rapidly, and this report adds a first-row transition metal (iron) complex to the known Ru catalysts recently reported. The featured system is well behaved and has been studied in detail by electrochemical methods. Cyclic voltammetry experiments in the presence of ammonia indicate an onset potential corresponding to ammonia oxidation at 0.7 V vs Fc/Fc⁺. Controlled potential coulometry (CPC) at an applied bias of 1.1 V confirms the generation of 16 equiv of N₂ with a Faradaic efficiency for N₂ of ~80%. Employing ¹⁵NH₃ yields exclusively ³⁰N₂, demonstrating the conversion of ammonia to N₂. A suite of electrochemical studies is consistent with an initial EC step that generates an Fe^III–NH₂ intermediate (at 0.4 V) followed by an anodically shifted catalytic wave. The data indicate a rate-determining step that is first order in both [Fe] and [NH₃] and point to a fast catalytic rate (k_obs) of ~10⁷ M^–1·s^–1 as computed by foot of the wave analysis (FOWA).

Authors:

^[1];

^[1]

California Institute of Technology (CalTech), Pasadena, CA (United States). Division of Chemistry and Chemical Engineering

Publication Date:: 2019-09-19

Research Org.:: California Institute of Technology (CalTech), Pasadena, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES); Gordon and Betty Moore Foundation (GBMF); California Institute of Technology (CalTech)

OSTI Identifier:: 1708895

Grant/Contract Number:: SC0019136

Resource Type:: Accepted Manuscript

Journal Name:: ACS Catalysis

Additional Journal Information:: Journal Volume: 9; Journal Issue: 11; Journal ID: ISSN 2155-5435

Publisher:: American Chemical Society (ACS)

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ammonia oxidation; iron catalysis; solar fuels; electrocatalysis; low-carbon fuels

Citation Formats


                    Zott, Michael D., Garrido-Barros, Pablo, and Peters, Jonas C. Electrocatalytic Ammonia Oxidation Mediated by a Polypyridyl Iron Catalyst.  United States: N. p., 2019. 
        Web.  doi:10.1021/acscatal.9b03499.

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                    Zott, Michael D., Garrido-Barros, Pablo, & Peters, Jonas C. Electrocatalytic Ammonia Oxidation Mediated by a Polypyridyl Iron Catalyst.  United States.  doi:10.1021/acscatal.9b03499.

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                    Zott, Michael D., Garrido-Barros, Pablo, and Peters, Jonas C. Thu .  
        "Electrocatalytic Ammonia Oxidation Mediated by a Polypyridyl Iron Catalyst".  United States.  doi:10.1021/acscatal.9b03499.  https://www.osti.gov/servlets/purl/1708895.

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@article{osti_1708895,

  title        = {Electrocatalytic Ammonia Oxidation Mediated by a Polypyridyl Iron Catalyst},

  author       = {Zott, Michael D. and Garrido-Barros, Pablo and Peters, Jonas C.},

  abstractNote = {Electrocatalytic ammonia oxidation (AO) mediated by iron(II) tris(2-pyridylmethyl)amine (TPA) bis-ammine triflate, [(TPA)Fe(NH3)2]OTf2, is reported. Interest in (electro)catalytic AO is growing rapidly, and this report adds a first-row transition metal (iron) complex to the known Ru catalysts recently reported. The featured system is well behaved and has been studied in detail by electrochemical methods. Cyclic voltammetry experiments in the presence of ammonia indicate an onset potential corresponding to ammonia oxidation at 0.7 V vs Fc/Fc+. Controlled potential coulometry (CPC) at an applied bias of 1.1 V confirms the generation of 16 equiv of N2 with a Faradaic efficiency for N2 of ~80%. Employing 15NH3 yields exclusively 30N2, demonstrating the conversion of ammonia to N2. A suite of electrochemical studies is consistent with an initial EC step that generates an FeIII–NH2 intermediate (at 0.4 V) followed by an anodically shifted catalytic wave. The data indicate a rate-determining step that is first order in both [Fe] and [NH3] and point to a fast catalytic rate (kobs) of ~107 M–1·s–1 as computed by foot of the wave analysis (FOWA).},

  doi          = {10.1021/acscatal.9b03499},

  journal      = {ACS Catalysis},

  number       = 11,

  volume       = 9,

  place        = {United States},

  year         = {2019},

  month        = {9}

}

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DOI: 10.1021/acscatal.9b03499

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Title: Electrocatalytic Ammonia Oxidation Mediated by a Polypyridyl Iron Catalyst

Abstract

Citation Formats

Triple hydrogen atom abstraction from Mn–NH 3 complexes results in cyclophosphazenium cations journal, January 2019

Triple hydrogen atom abstraction from Mn–NH 3 complexes results in cyclophosphazenium cations
journal, January 2019