Hydronium ion diffusion in model proton exchange membranes at low hydration: insights from <i>ab initio</i> molecular dynamics

Zelovich, Tamar; Winey, Karen I.; Tuckerman, Mark E.

doi:10.1039/d0ta10565a

Cited by 26 publications

(71 citation statements)

References 88 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based on the results presented in Section 4.3.1 and combined with inspection of configurations from the AIMD trajectory, we propose, in Figure 8, an idealized diffusion mechanism for hydronium ions in the PEM model under idealized hydration conditions (λ = 3) [55]. First, the hydronium ion is located in the center of the cell, solvated by three water molecules (Figure 8a).…”

Section: H 3 O + Diffusion Mechanismmentioning

confidence: 82%

“…Dispersion forces were accounted for using the Dispersion-Corrected Atomic Core Pseudopotential (DCACP) scheme [61,62] within the Kohn-Sham formulation of Density Functional Theory using the B-LYP exchange-correlation functional [63,64]. The B-LYP+DCACP has been selected for this study, as it has previously been shown to produce satisfactory results for water-acene interactions [65], liquid water [66], and hydronium diffusion in bulk water [38][39][40]67] A detailed description of the construction of the initial structures and of the computational methodology can be found in the Supplementary Information (SI) and in References [52][53][54][55].…”

Section: Methodsmentioning

confidence: 99%

“…Hydroxide and hydronium ions serve as charge carriers, respectively in AEMs and PEMs, and these systems are then solvated with water molecules [57]. In previous studies, we explored different GB systems as mimics of different AEM and PEM environments [52][53][54][55] in which the nanoconfined structure in these systems model the layered arrangement recently reported in References [16,57]. Of the various systems studied, we ultimately chose two representative examples that best captured the hydroxide and hydronium ion diffusion mechanisms described above.…”

Section: Description Of Systemsmentioning

confidence: 99%

“…The distance ∆z is calculated as the distance between the hydrogen atoms on the inner surfaces of the graphane layers and is determined by λ, with a lower bound determined by the height of the cations/anions. These AEM and PEM models were previously referred to as systems a4 and λ3 in References [53,55], respectively.…”

Section: Description Of Systemsmentioning

confidence: 99%

“…To verify this, we calculate the percentage of time that the hydronium ions spent as SO − 3 and SO 3 H, which shows that the hydronium ion appears as SO 3 H for 48.78% of the simulation time (see inset of Figure 6). and SO3H (a detailed description of the calculation can be found in Reference [55]). This leads us to conclude that the protonation state of the sulfonate group is a significant factor in the hydronium ion diffusion mechanism, as the reaction:…”

Section: Hydronium Ion Diffusion In the Pemmentioning

confidence: 99%

See 4 more Smart Citations

OH− and H3O+ Diffusion in Model AEMs and PEMs at Low Hydration: Insights from Ab Initio Molecular Dynamics

Zelovich

Tuckerman

2021

Membranes

Self Cite

View full text Add to dashboard Cite

Fuel cell-based anion-exchange membranes (AEMs) and proton exchange membranes (PEMs) are considered to have great potential as cost-effective, clean energy conversion devices. However, a fundamental atomistic understanding of the hydroxide and hydronium diffusion mechanisms in the AEM and PEM environment is an ongoing challenge. In this work, we aim to identify the fundamental atomistic steps governing hydroxide and hydronium transport phenomena. The motivation of this work lies in the fact that elucidating the key design differences between the hydroxide and hydronium diffusion mechanisms will play an important role in the discovery and determination of key design principles for the synthesis of new membrane materials with high ion conductivity for use in emerging fuel cell technologies. To this end, ab initio molecular dynamics simulations are presented to explore hydroxide and hydronium ion solvation complexes and diffusion mechanisms in the model AEM and PEM systems at low hydration in confined environments. We find that hydroxide diffusion in AEMs is mostly vehicular, while hydronium diffusion in model PEMs is structural. Furthermore, we find that the region between each pair of cations in AEMs creates a bottleneck for hydroxide diffusion, leading to a suppression of diffusivity, while the anions in PEMs become active participants in the hydronium diffusion, suggesting that the presence of the anions in model PEMs could potentially promote hydronium diffusion.

show abstract

Section: H 3 O + Diffusion Mechanismmentioning

confidence: 82%

Section: Methodsmentioning

confidence: 99%

Section: Description Of Systemsmentioning

confidence: 99%

Section: Description Of Systemsmentioning

confidence: 99%

Section: Hydronium Ion Diffusion In the Pemmentioning

confidence: 99%

See 3 more Smart Citations

OH− and H3O+ Diffusion in Model AEMs and PEMs at Low Hydration: Insights from Ab Initio Molecular Dynamics

Zelovich

Tuckerman

2021

Membranes

Self Cite

View full text Add to dashboard Cite

show abstract

Hierarchically Macro–Microporous Covalent Organic Frameworks for Efficient Proton Conduction

Zou

Jiang

Zhang

et al. 2023

Adv Funct Materials

View full text Add to dashboard Cite

Assembling molecular proton carriers into crosslinked networks is widely used to fabricate proton conductors, but they often suffer losses in conduction efficiency and stability accompanied by unclear causes. Covalent organic frameworks (COFs), with well-defined crystal frameworks and excellent stability, offer a platform for exploring the proton transfer process. Herein, a strategy to construct proton conductors that induce conductivity and stability by introducing bottom-up hierarchical structure, mass transport interfaces, and host-guest interactions into the COFs is proposed. The proton-transport platforms are designed to possess hierarchically macro-microporous structure for proton storage and mass transport. The protic ionic liquids, with low proton dissociation energies investigated by DFT calculation, are installed at open channel walls for faster proton motion. As expected, the resultant proton conductors based on a covalent organic framework (PIL 0.5 @m-TpPa-SO 3 H) with hierarchical pores increase conductivity by approximately three orders of magnitude, achieving the value of 1.02 × 10 −1 S cm −1 (90 °C, 100% RH), and maintain excellent stability. In addition, molecular dynamics simulations reveal the mechanism of "hydrogen-bond network" for proton conduction. This work offers a fresh perspective on COF-based material manufacturing for high-performance proton conductors via a protocol of macro-micropores.

show abstract

Proton Traffic Jam: Effect of Nanoconfinement and Acid Concentration on Proton Hopping Mechanism

et al. 2021

View full text Add to dashboard Cite

The properties of the water network in concentrated HCl acid pools in nanometer-sized reverse nonionic micelles were probed with TeraHertz absorption, dielectric relaxation spectroscopy, and reactive force field simulations capable of describing proton hopping mechanisms.W ei dentify that only at acritical micelle size of W 0 = 9dosolvated proton complexes form in the water pool, accompanied by ac hangei n mechanism from Grotthuss forwards huttling to one that favors local oscillatory hopping.This is due to apreference for H + and Cl À ions to adsorb to the micelle interface,together with an acid concentration effect that causes a"traffic jam" in which the short-circuiting of the hydrogen-bonding motif of the hydronium ion decreases the forward hopping rate throughout the water interior even as the micelle sizei ncreases.T hese findings have implications for atmospheric chemistry,b iochemical and biophysical environments,and energy materials, as transport of protons vital to these processes can be suppressed due to confinement, aggregation, and/or concentration.

show abstract

Hydronium ion diffusion in model proton exchange membranes at low hydration: insights from ab initio molecular dynamics

Abstract: Sequence of steps in the reaction of hydronium (H3O+) with sulfonate (SO3−) contributing to the proton structural diffusion mechanism in a low-hydration environment of a proton-exchange-membrane (PEM) mimic.

Cited by 26 publications

References 88 publications

OH− and H3O+ Diffusion in Model AEMs and PEMs at Low Hydration: Insights from Ab Initio Molecular Dynamics

OH− and H3O+ Diffusion in Model AEMs and PEMs at Low Hydration: Insights from Ab Initio Molecular Dynamics

Hierarchically Macro–Microporous Covalent Organic Frameworks for Efficient Proton Conduction

Proton Traffic Jam: Effect of Nanoconfinement and Acid Concentration on Proton Hopping Mechanism

Contact Info

Product

Resources

About