Base-PA

Files of the projiect about Base-PA interaction

Boosting Phosphoric Acid Retention in Polymer Electrolyte Membranes by Zwitterions: Insights from DFT Calculations and MD Simulations

Abstract

Effective retention of phosphoric acid (PA) is crucial for the efficient operation of fuel cells based on PA-doped polymeric membranes, which is highly challenging due to the moisture-induced loss of PA. Therefore, a comprehensive understanding of the interplay between PA, functional groups, and water is essential for designing membrane materials. Using density functional theory (DFT) calculations and molecular dynamics (MD) simulations, we unveil the remarkable capability of zwitterions to efficaciously sequester PA, thereby unlocking the potential for fuel cell optimization. Our DFT calculations show that zwitterions, referred to as “charged proton-accepting bases”, exhibit higher interaction energies with PA compared to the traditional neutral proton-accepting bases. Further, the presence of water amplifies such a discrepancy, with the zwitterion-PA interactions playing a dominant role in the zwitterion-PA-water cluster due to the strongest affinity of zwitterions to PA. Conversely, the ability of neutral bases to retain PA is significantly attenuated by moisture as the interactions between water and PA surpass those between neutral bases and PA. The strong zwitterion-PA associations arise primarily from the formation of multiple hydrogen bonds. Furthermore, MD simulations reveal the uniform distribution of zwitterions in aqueous environments and their pronounced affinities to both PA and water. In contrast, neutral bases tend to aggregate, interacting limitedly with PA. These findings underscore the effectiveness of zwitterions in boosting PA retention in fuel cells.

NOTE

This repository contains the calculation and simulation files used in the Base-PA interactions project. In the early stages of the study, the abbreviations for base molecules differed from those used in the published work. Here are the corresponding relationships for the base molecules.

• TMAPS - QASO3

• TMABA - QACOO

• MImPS - MImSO3

• MImBA - MImCOO

• MPyPS - MPySO3

• MPyBA - MPyCOO

1. Interaction Energy Calculation

2. Decomposition of Interaction Energy by SAPT method

3. ESP Analysis

4. Interaction Energy Calculation in the Presence of Water

5. MD simulation

6. Solvation Free Energy