DFT-based computational investigation of the structural, electronic, and thermoelectric properties of transition-metal hydride VH2

Abstract

Context

Vanadium hydride is of significant interest because of its potential applications in thermoelectric materials and hydrogen storage technologies. Understanding its structural, electronic, and thermoelectric properties is crucial for optimizing its performance in these applications. This study investigates these properties via density functional theory (DFT), revealing key insights into its stability and efficiency as a thermoelectric material.

Methods

In this work, the structural, electronic, and thermoelectric properties of cubic VH₂ were investigated using the GGA approach within the framework of DFT. The band structure and density of states demonstrate the metallic nature of these compounds. Using the semi-empirical Boltzmann’s approach implemented in the BoltzTraP code, transport parameters, such as the Seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit as a function of the chemical potential, are computed at a temperature gradient of 500 K. For the VH₂ compound, the thermal and electrical conductivities and Seebeck coefficient are greater for p-type doping and n-type doping. The moderate values of the figure of merit obtained for these materials indicate that these materials have applicability where small values of thermoelectric efficiency are required, and higher values can harm the process. The maximum values of the Seebeck coefficient for VH₂ against chemical potential values ranging between 0.095 and − 0.095 eV in the p-type region and n-type region are 2.28 µV/K and − 2.27 µV/K, respectively. The highest value of electrical conductivity per relaxation time in the chemical potential range between − 0.07 and 0.07 eV in the p-type region is 5.3 × 10²⁰1/Ωms, and that in the n-type region is 1.97 × 10²⁰1/Ωms. The maximum dimensionless figure of merit value for VH₂ is 0.020.