Electrolyte acidification from anode reactions during lithium mediated ammonia synthesis

Krempl, Kevin; Pedersen, Jakob B.; Kibsgaard, Jakob; Vesborg, Peter Christian Kjærgaard; Chorkendorff, Ib

doi:10.1016/j.elecom.2021.107186

Cited by 23 publications

(47 citation statements)

References 23 publications

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“…At the working electrode, nitrogen is reduced to form ammonia. The counter electrode reaction is not controlled, but likely involves solvent oxidation, as previously documented in the field 18,36,37 . A change in working electrode potential stability is observed upon changing the LiClO 4 concentration from 0.2 M to 1.4 M. A transition to much improved stability is S1), as well as consumption of ethanol changing the proton donor concentration over the course of a longer experiment.…”

Section: Electrochemical Resultsmentioning

confidence: 94%

The role of ion solvation in lithium mediated nitrogen reduction

et al. 2023

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Section: Electrochemical Resultsmentioning

confidence: 94%

The role of ion solvation in lithium mediated nitrogen reduction

et al. 2023

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“…At 0.2 M LiClO4, the potential remains stable at approximately 6 V vs Li + /Li, whereas the more concentrated samples all have lower counter electrode potentials at around 4 V vs Li + /Li. Given that the anode reaction is not controlled in this setup, it is likely that it involves electrolyte oxidation 32 , which will be the subject of further studies. Figure S7 shows the change in the DFT-calculated HOMO-LUMO (Highest Occupied Molecular Orbital -Lowest Unoccupied Molecular Orbital) of THF at various concentrations of LiClO4.…”

Section: Section 2: Electrochemical Resultsmentioning

confidence: 99%

The Role of Ion Solvation in Lithium Mediated Nitrogen Reduction

Westhead

Spry

Bagger

et al. 2022

Preprint

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Since its verification in just 2019, there have been numerous high-profile papers reporting improved efficiency of the lithium-mediated electrochemical nitrogen reduction system to make ammonia. However, the literature lacks a cohesive investigation systematically linking bulk electrolyte properties to electrochemical performance and Solid Electrolyte Interphase (SEI) properties. In this study, we vary electrolyte salt concentration and observe a transition from an unstable working electrode potential to working electrode potential stability and peak in Faradaic efficiency of 7.8 ± 0.5 % at 0.6 M LiClO4. The behaviour is linked to the formation of Solvent Separated Ion Pairs in the electrolyte through Raman spectroscopy. Time of Flight Secondary Ion Mass Spectrometry and X-Ray Photoelectron Spectroscopy reveal a more inorganic, and therefore more stable, SEI layer with increasing salt concentration. A drop in Faradaic efficiency is seen at concentrations higher than 0.6 M LiClO4, which is attributed to a combination of a loss in nitrogen solubility and diffusivity as well as increased SEI conductivity as measured by Electrochemical Impedance Spectroscopy.

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“…In order to facilitate the protonation of the adsorbed N 2 molecules, it is necessary to maintain a proton sufficiency in the medium. This makes the use of acidic electrolyte an optimum choice for NRR [57][58][59]. In fact, acidic electrolyte acts as a proper trap to capture all the converted ammonia in form of NH 4 + .…”

Section: Electrochemical Nrr Performance: Role Of Electrolyte Anions ...mentioning

confidence: 99%

Oxygen Functionalization-Induced Charging Effect on Boron Active Sites for High-Yield Electrocatalytic NH3 Production

et al. 2022

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Ammonia has been recognized as the future renewable energy fuel because of its wide-ranging applications in H2 storage and transportation sector. In order to avoid the environmentally hazardous Haber–Bosch process, recently, the third-generation ambient ammonia synthesis has drawn phenomenal attention and thus tremendous efforts are devoted to developing efficient electrocatalysts that would circumvent the bottlenecks of the electrochemical nitrogen reduction reaction (NRR) like competitive hydrogen evolution reaction, poor selectivity of N2 on catalyst surface. Herein, we report the synthesis of an oxygen-functionalized boron carbonitride matrix via a two-step pyrolysis technique. The conductive BNCO(1000) architecture, the compatibility of B-2pz orbital with the N-2pz orbital and the charging effect over B due to the C and O edge-atoms in a pentagon altogether facilitate N2 adsorption on the B edge-active sites. The optimum electrolyte acidity with 0.1 M HCl and the lowered anion crowding effect aid the protonation steps of NRR via an associative alternating pathway, which gives a sufficiently high yield of ammonia (211.5 μg h−1 mgcat−1) on the optimized BNCO(1000) catalyst with a Faradaic efficiency of 34.7% at − 0.1 V vs RHE. This work thus offers a cost-effective electrode material and provides a contemporary idea about reinforcing the charging effect over the secured active sites for NRR by selectively choosing the electrolyte anions and functionalizing the active edges of the BNCO(1000) catalyst.

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Electrolyte acidification from anode reactions during lithium mediated ammonia synthesis

Cited by 23 publications

References 23 publications

The role of ion solvation in lithium mediated nitrogen reduction

The role of ion solvation in lithium mediated nitrogen reduction

The Role of Ion Solvation in Lithium Mediated Nitrogen Reduction

Oxygen Functionalization-Induced Charging Effect on Boron Active Sites for High-Yield Electrocatalytic NH3 Production

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