Electrochemistry of nitrogen and nitrides in molten salts

Ito, Yasuhiko; Goto, Takuya

doi:10.1016/j.jnucmat.2005.04.030

“…5. This result proves that the anodic peak is attributed to the nitride ions oxidation, in agreement with results presented by Ito et al in molten chlorides [4].…”

Section: Selection Of Anodic Electrode Materialssupporting

confidence: 93%

“…This value can be compared to the results of Ito et al [4] who obtained a similar value of 1.8 × 10 −9 m 2 s −1 in molten LiCl-KCl at 723 K.…”

Section: Diffusion Coefficient Determinationsupporting

confidence: 75%

“…All the previous studies concerning the electrochemical behaviour of nitrides, presented in the bibliography, have been performed in molten chlorides. Ito et al examined the N 2(g) /N 3− electrochemical system in molten LiCl-KCl at 723 K [4]. The electrochemical reduction of nitrogen into nitride ions on a nickel cathode was investigated and the reaction standard potential experimentally determined.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nitrogen evolution as anodic reaction in molten LiF–CaF2

Massot

¹

,

Chamelot

²

,

Gibilaro

³

et al. 2011

Electrochimica Acta

2

0

View full text Add to dashboard Cite

The electrochemical behaviour of nitride ions has been studied in fluoride melts (eutectic LiF-CaF 2) by cyclic voltammetry and square wave voltammetry. The purpose of this work is to propose an alternative way for anodic reaction in molten fluorides processes. Thermodynamical analysis can be used for the evaluation of the anodic material regarding to its oxidation potential and reactivity with nitrogen. Then electrochemical investigations confirm the oxidation of nitride ions into nitrogen in a one-step process exchanging 3 electrons, and let propose several materials usable for nitrogen evolving.

show abstract

“…[7][8][9][10][11][12] In particular, it has been reported that molten LiCl, and related eutectics,p ossess the fascinating ability to stabilise the N 3À ion and establish the reversible N 2 /N 3À redox couple at ambient pressure. [13][14][15][16] Ito and co-workers proposed that this could be utilised in an ammonia synthesis process,by coupling the reduction of N 2 [Eq. (1)] at ac athode with its oxidation in the presence of H 2 [Eq.…”

Section: Introductionmentioning

confidence: 99%

The Feasibility of Electrochemical Ammonia Synthesis in Molten LiCl–KCl Eutectics

McPherson

¹

,

Sudmeier

²

,

Fellowes

³

et al. 2019

View full text Add to dashboard Cite

Molten LiCl and related eutectic electrolytes are known to permit direct electrochemical reduction of N2 to N3− with high efficiency. It had been proposed that this could be coupled with H2 oxidation in an electrolytic cell to produce NH3 at ambient pressure. Here, this proposal is tested in a LiCl–KCl–Li3N cell and is found not to be the case, as the previous assumption of the direct electrochemical oxidation of N3− to NH3 is grossly over‐simplified. We find that Li3N added to the molten electrolyte promotes the spontaneous and simultaneous chemical disproportionation of H2 (H oxidation state 0) into H− (H oxidation state −1) and H+ in the form of NH2−/NH2−/NH3 (H oxidation state +1) in the absence of applied current, resulting in non‐Faradaic release of NH3. It is further observed that NH2− and NH2− possess their own redox chemistry. However, these spontaneous reactions allow us to propose an alternative, truly catalytic cycle. By adding LiH, rather than Li3N, N2 can be reduced to N3− while stoichiometric amounts of H− are oxidised to H2. The H2 can then react spontaneously with N3− to form NH3, regenerating H− and closing the catalytic cycle. Initial tests show a peak NH3 synthesis rate of 2.4×10−8 mol cm−2 s−1 at a maximum current efficiency of 4.2 %. Isotopic labelling with 15N2 confirms the resulting NH3 is from catalytic N2 reduction.

show abstract

“…Several electrochemical cells have been proposed for ammonia synthesis, with those based on molten salt electrolytes reporting the highest rates and current efficiencies . In particular, it has been reported that molten LiCl, and related eutectics, possess the fascinating ability to stabilise the N 3− ion and establish the reversible N 2 /N 3− redox couple at ambient pressure . Ito and co‐workers proposed that this could be utilised in an ammonia synthesis process, by coupling the reduction of N 2 [Eq.…”

Section: Introductionmentioning

confidence: 99%

The Feasibility of Electrochemical Ammonia Synthesis in Molten LiCl–KCl Eutectics

McPherson

¹

,

Sudmeier

²

,

Fellowes

³

et al. 2019

View full text Add to dashboard Cite

Molten LiCl and related eutectic electrolytes are known to permit direct electrochemical reduction of N2 to N3− with high efficiency. It had been proposed that this could be coupled with H2 oxidation in an electrolytic cell to produce NH3 at ambient pressure. Here, this proposal is tested in a LiCl–KCl–Li3N cell and is found not to be the case, as the previous assumption of the direct electrochemical oxidation of N3− to NH3 is grossly over‐simplified. We find that Li3N added to the molten electrolyte promotes the spontaneous and simultaneous chemical disproportionation of H2 (H oxidation state 0) into H− (H oxidation state −1) and H+ in the form of NH2−/NH2−/NH3 (H oxidation state +1) in the absence of applied current, resulting in non‐Faradaic release of NH3. It is further observed that NH2− and NH2− possess their own redox chemistry. However, these spontaneous reactions allow us to propose an alternative, truly catalytic cycle. By adding LiH, rather than Li3N, N2 can be reduced to N3− while stoichiometric amounts of H− are oxidised to H2. The H2 can then react spontaneously with N3− to form NH3, regenerating H− and closing the catalytic cycle. Initial tests show a peak NH3 synthesis rate of 2.4×10−8 mol cm−2 s−1 at a maximum current efficiency of 4.2 %. Isotopic labelling with 15N2 confirms the resulting NH3 is from catalytic N2 reduction.

show abstract

Electrochemistry of nitrogen and nitrides in molten salts

Cited by 22 publications

References 14 publications

Nitrogen evolution as anodic reaction in molten LiF–CaF2

Nitrogen evolution as anodic reaction in molten LiF–CaF2

The Feasibility of Electrochemical Ammonia Synthesis in Molten LiCl–KCl Eutectics

The Feasibility of Electrochemical Ammonia Synthesis in Molten LiCl–KCl Eutectics

Contact Info

Product

Resources

About