Hydrogenation Properties of the TiBx Structures

TL;DR

This study uses density functional theory to analyze hydrogen binding energies and structural relaxation in various hydrogenated titanium boride structures, revealing differences in stability and potential soft modes.

Contribution

It provides a comprehensive computational analysis of hydrogen adsorption sites and energies in TiB2, TiB, and Ti2B, identifying stable configurations and energetic properties.

Findings

TiB2 has the lowest binding energies (0.3-1.8 eV)

Ti2B exhibits the highest binding energies (3.9-4.7 eV)

Hydrogenated Ti2B shows two stable sites indicating a possible soft mode

Abstract

Titanium borates show promissing hydrogen storage characteristics. Structural relaxation around individual hydrogen atoms and the binding energies are studied by means of the density functional theory methods for a number of hydrogenated TiB2, TiB and Ti2B structures. Starting with the possible symmetric hydrogen sites a random structure searching has been performed, in addition to locate all energetically stable adsorption sites. It is shown that for the three bulk compounds considered, the lowest binding energies are obtained for TiB2 (in the 0.3-1.8 eV range), the largest for Ti2B (in the 3.9-4.7 eV range), while for TiB they are intermediate (in the 2.8-3.5 eV range). Calculations performed on hydrogenated Ti2B result in two energetically stable sites for two different starting environments, suggesting a posible soft mode solution.