Vanadium-decorated 2D polyaramid material for high-capacity hydrogen storage: Insights from DFT simulations

Abstract

Herein, systematic computational investigations comprising density functional theory and ab initio molecular dynamics simulations (AIMD) have been conducted to assess the viability of vanadium decoration over the newly synthesized 2D polyaramid material (2DPA-I) as a potentially reversible hydrogen storage substrate for light fuel cell vehicles. The binding energies of V at different positions over 2DPA-I were compared, and the optimum site for V decoration was in the plane of 2DPA-I. The H2 binding ability of V-decorated 2DPA-I was improved over that of pristine 2DPA-I by 185.71 %. A single V atom decorated over 2DPA-I can effectively bind 7 H2 molecules, with a gravimetric H2 storage capacity of ~7.3 wt% and desorption temperature ~330 K at a favourable binding energy window (~−0.4 eV) to facilitate reversible H2 binding. V-decorated 2DPA-I remained stable at elevated temperatures as verified by AIMD simulations, and a substantial energy barrier of ~3 eV exists for the movement of the V atom across the 2DPA-I surface. The interaction of V with 2DPA-I and H2 with V-decorated 2DPA-I proceeds with a charge flow from the V atom towards H2 and 2DPA-I, respectively. The binding energy and charge transfer analysis of the interaction of H2 with V-decorated 2DPA-I indicates possible Kubas interactions. We predict that V-decorated 2DPA-I has immense potential for on-board H2 storage applications in light fuel cell vehicles.