Enhancement in hydrogen storage capacities of light metal functionalized Boron Graphdiyne nanosheets

TL;DR

This study uses DFT calculations to show that light-metal functionalized boron-graphdiyne nanosheets can store hydrogen at capacities surpassing many other 2D materials, with stable and practical adsorption/desorption properties.

Contribution

It demonstrates the high hydrogen storage capacities of metal-doped BGDY nanosheets and confirms their stability and practical usability through ab initio simulations.

Findings

High H2 storage capacities: Li (14.29 wt%), Na (11.11 wt%), K (9.10 wt%), Ca (8.99 wt%)

Stable metal functionalization confirmed by molecular dynamics

H2 adsorption energies within ideal range (0.17-0.40 eV/H2)

Abstract

The recent experimental synthesis of the two-dimensional (2D)boron-graphdiyne (BGDY) nanosheet has motivated us to investigate its structural, electronic,and energy storage properties. BGDY is a particularly attractive candidate for this purpose due to uniformly distributed pores which can bind the light-metal atoms. Our DFTcalculations reveal that BGDY can accommodate multiple light-metal dopants (Li, Na, K, Ca)with significantly high binding energies. The stabilities of metal functionalized BGDY monolayers have been confirmed through ab initio molecular dynamics simulations. Furthermore, significant charge-transfer between the dopantsand BGDY sheet renders the metal with a significant positive charge, which is a prerequisite for adsorbing hydrogen (H2) molecules with appropriate binding energies.This results in exceptionally high H2 storage capacities of 14.29, 11.11, 9.10 and 8.99 wt% for the Li, Na, K and Ca dopants, respectively. These H2storage capacities are much higher than many 2D materials such as graphene, graphane, graphdiyne, graphyne, C2N, silicene, and phosphorene. Average H2 adsorption energies for all the studied systems fall within an ideal window of 0.17-0.40 eV/H2. We have also performed thermodynamic analysis to study the adsorption/desorption behavior of H2, which confirmsthat desorption of the H2molecules occurs at practical conditions of pressure and temperature.