Ammonia synthesis from N<sub>2</sub>and H<sub>2</sub>O using a lithium cycling electrification strategy at atmospheric pressure

McEnaney, Joshua M.; Singh, Aayush R.; Schwalbe, Jay A.; Kibsgaard, Jakob; Lin, Joseph; Cargnello, Matteo; Jaramillo, Thomas F.; Nørskov, Jens K.

doi:10.1039/c7ee01126a

Cited by 393 publications

(429 citation statements)

References 37 publications

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“…9 We recommend testing multiple MEAs to improve reproducibility and MEAs that have not been pre-exchanged with ammonium whose leaking can significantly interfere with the quantification of ammonia production rate and faradaic efficiency. In the previous work, NH 4 + -exchanged membranes were used for ENRR. 9 Since H + produced on the anode is transported via the membrane to the cathode, the possibility of the NH 4 + in the PEM prior to reaction getting displaced by H + and evolved on the hydrogen side cannot be excluded, especially when the amount of NH 4 + in the NH 4 + -exchanged membrane was comparable to the amount of detected ammonia.…”

Section: Resultsmentioning

confidence: 99%

“…In the previous work, NH 4 + -exchanged membranes were used for ENRR. 9 Since H + produced on the anode is transported via the membrane to the cathode, the possibility of the NH 4 + in the PEM prior to reaction getting displaced by H + and evolved on the hydrogen side cannot be excluded, especially when the amount of NH 4 + in the NH 4 + -exchanged membrane was comparable to the amount of detected ammonia. The fact that ammonia was also observed on the anode side in the previous study indicates that leaching of ammonium, either through ion-exchange or degradation, from the Nafion membrane is likely occurring.…”

Section: Resultsmentioning

confidence: 99%

“…Distributed and modular ammonia synthesis via the electrochemical nitrogen reduction reaction (ENRR) at or close to ambient conditions, powered by renewable electricity, is an attractive alternative because it allows as-needed production of ammonia, and in turn N-fertilizers, from ubiquitously available resources, i.e., N 2 and water. 4 Widespread adoption of ENRR for ammonia production could drastically reduce the carbon footprint of agricultural activities. In addition, ENRR is compatible with the intermittency of renewable energy sources, e.g., solar and wind, as the ammonia and N-fertilizers can be produced and stored when renewable electricity is available.…”

mentioning

confidence: 99%

“…1 The development of the Haber-Bosch process revolutionized modern agriculture, 2 however, the centralized, energy and carbon intensive nature of the Haber-Bosch process [3][4][5] leaves many aspects to be desired. Distributed and modular ammonia synthesis via the electrochemical nitrogen reduction reaction (ENRR) at or close to ambient conditions, powered by renewable electricity, is an attractive alternative because it allows as-needed production of ammonia, and in turn N-fertilizers, from ubiquitously available resources, i.e., N 2 and water.…”

mentioning

confidence: 99%

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Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Nash

Yang

Anibal

et al. 2017

J. Electrochem. Soc.

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Five noble metal catalysts (Pt/C, Ir/C, Pd/C, Ru/C, and Au/C) are evaluated for electrochemical nitrogen reduction reaction (ENRR) to produce ammonia in both proton exchange membrane (PEM) and hydroxide exchange membrane (HEM) electrolyzers (PEMELs and HEMELs). The competing hydrogen evolution reaction (HER) is found to be the dominant reaction on all catalysts tested in both PEMELS and HEMELs, which is consistent with recent computational predictions that metallic catalysts are unlikely to be selective for ENRR. With the increase of applied potentials, the rate of HER increase significantly, which suppresses the ENRR, leading to significant decreases of faradaic efficiencies. Leaching of quaternary ammonium from HEM is found to interfere with ammonia quantification, which necessitates a pretreatment protocol. Due to the relatively slow kinetics of HER in alkaline solution, faradaic efficiencies in HEMELs are generally higher than those in PEMELs. We believe that these results provide a solid baseline for future research on ENRR in both PEMELs and HEMELs. Ammonia synthesis is one of the foundational chemical processes to the human society, which is estimated to supported approximately 27% of the world's population over the past century.1 The development of the Haber-Bosch process revolutionized modern agriculture, 2 however, the centralized, energy and carbon intensive nature of the Haber-Bosch process 3-5 leaves many aspects to be desired. Distributed and modular ammonia synthesis via the electrochemical nitrogen reduction reaction (ENRR) at or close to ambient conditions, powered by renewable electricity, is an attractive alternative because it allows as-needed production of ammonia, and in turn N-fertilizers, from ubiquitously available resources, i.e., N 2 and water. 4 Widespread adoption of ENRR for ammonia production could drastically reduce the carbon footprint of agricultural activities. In addition, ENRR is compatible with the intermittency of renewable energy sources, e.g., solar and wind, as the ammonia and N-fertilizers can be produced and stored when renewable electricity is available.Electrochemical fixation of atmospheric nitrogen was first attempted in 1908 even before the establishment of the Haber-Bosch process, to make nitric acid via electric discharge. 6 Further studies of ENRR have generally been focused on high temperature proton conductors at 500• C, 7 however, the high operating temperature and the stability of ammonia at such conditions make it unsuitable for distributed deployment. Proton exchange membranes (PEMs) can achieve high proton conductivity (∼100 mS·cm −1 at 25 • C for Nafion) at ambient or slightly elevated temperatures, which opens the possibility for electrochemical ammonia synthesis at those mild conditions. 8 Although Nafion-based low temperature electrochemical ammonia synthesis has been demonstrated in several reports, 9-15 no systematic investigation of noble metal catalysts exists.2 Further, the alkaline environment of hydroxide exchange membranes (HEMs) promises the...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Nash

Yang

Anibal

et al. 2017

J. Electrochem. Soc.

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“…

Despite recent intense interest in the development of catalysts for the electrochemical nitrogen reduction reaction (ENRR), mechanistic understanding and catalyst design principles remain lacking. [2][3][4][5][6][7] Distributed and modular ammonia synthesis via the electrochemical nitrogen reduction reaction (ENRR) at or close to ambient conditions,p owered by renewable electricity is an attractive alternative because it allows as-needed and on-site production of ammonia, and in turn N-fertilizers,from N 2 and water. This method allows the comparison of intrinsic activities of active sites and facilitates the identification and improvement of active-site structures for ENRR.

…”

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confidence: 99%

Quantification of Active Sites and Elucidation of the Reaction Mechanism of the Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride

et al. 2019

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Despite recent intense interest in the development of catalysts for the electrochemical nitrogen reduction reaction (ENRR), mechanistic understanding and catalyst design principles remain lacking. In this work, we develop as trategy to determine the density of initial and steady-state active sites on ENRR catalysts that follow the Mars-van Krevelen mechanism via quantitative isotope-exchange experiments. This method allows the comparison of intrinsic activities of active sites and facilitates the identification and improvement of active-site structures for ENRR. Combined with detailed density functional theory calculations,w es how that the ratelimiting step in the ENRR is likely the initial N Nb ond activation via the addition of ap roton and an electron to the adsorbed N 2 on the Nv acancies to form N 2 H. The methodology developed and mechanistic insights gained in this work could guide the rational catalyst design in the ENRR.Ammonia synthesis via the Haber-Bosch process is ap illar of modern agriculture,which converts the abundant but inert dinitrogen in the atmosphere to the key precursor of nitrogenbased fertilizers (N-fertilizers). [1] Despite more than acentury of optimization, the Haber-Bosch process remains energy and carbon intensive. [2][3][4][5][6][7] Distributed and modular ammonia synthesis via the electrochemical nitrogen reduction reaction (ENRR) at or close to ambient conditions,p owered by renewable electricity is an attractive alternative because it allows as-needed and on-site production of ammonia, and in turn N-fertilizers,from N 2 and water. [3] Widespread adoption of the ENRR for ammonia production could drastically reduce the carbon footprint of agricultural activities.ENRR is also compatible with the intermittencyo fr enewable energy sources,e .g., solar and wind energy,a sa mmonia and Nfertilizers can be produced and stored when renewable electricity is abundant or even in surplus.Ar ecent flurry of studies on the ENRR led to the discovery of many catalysts with remarkable ammonia production rates and selectivities. [8][9][10][11][12][13][14][15][16][17][18] Mechanistic insights gained so far lean heavily on computational investigations, with relatively little experimental input and insufficient theory/experiment integration. Forexample,reported ammonia production rates are typically normalized by the geometric area or electrochemical surface area determined by capacitance measurements, [19] which make the comparison of the intrinsic activity among different catalysts challenging. Catalyst development based on the comparison of (electrochemical) surface area normalized activities risks missing highly active structures/phases if they exist in low densities. Our recent work highlights this risk, as VN 0.7 O 0.45 ,rather than the bulk VN phase,inthe vanadium nitride (referred to as the oxygen-modified VN catalyst, or VNO below) is identified as the active phase. [10] Thus,i dentification and quantification of active sites in the ENRR are key to developing catalyst design principles. [20]...

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Nitrogen Fixation Reaction Derived from Nanostructured Catalytic Materials

Wang

Ichihara

Pang

et al. 2018

Adv Funct Materials

246

197

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An efficient nitrogen fixation reaction is highly desirable for obtaining the essential chemicals and energy carriers but remains a challenge due to the strong nonpolar bonding and considerable activation barrier of the NN triple bond (bond energy 940.95 kJ mol−1). Using an appropriate nanostructured catalyst that strongly interacts with nitrogen could promote adsorption and activation, lowering the energy barrier of nitrogen fixation and thus resulting in a relatively mild reaction. In this article, the review of the recent progress in nanostructured catalytic materials for nitrogen fixation is presented, including a comprehensive introduction and discussion on the pathway and mechanism of nitrogen fixation reaction, the recent achievements of a variety of nanostructured catalysts, and the kinds of catalytic nitrogen fixation reactions they are used in. In addition, the challenges faced by the reaction, strategies of catalyst design, and outlooks for further improving the performance of nitrogen fixation are also highlighted.

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Ammonia synthesis from N₂and H₂O using a lithium cycling electrification strategy at atmospheric pressure

Abstract: An electrochemical, lithium-mediated looping method for efficiently producing NH3from N2and H2O at ambient pressure.

Cited by 393 publications

References 37 publications

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Quantification of Active Sites and Elucidation of the Reaction Mechanism of the Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride

Nitrogen Fixation Reaction Derived from Nanostructured Catalytic Materials

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Ammonia synthesis from N2and H2O using a lithium cycling electrification strategy at atmospheric pressure

Abstract: An electrochemical, lithium-mediated looping method for efficiently producing NH3from N2and H2O at ambient pressure.

Cited by 393 publications

References 37 publications

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Quantification of Active Sites and Elucidation of the Reaction Mechanism of the Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride

Nitrogen Fixation Reaction Derived from Nanostructured Catalytic Materials

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Ammonia synthesis from N₂and H₂O using a lithium cycling electrification strategy at atmospheric pressure