Density-functional quantum computations on bandgap engineering and tuning of optoelectronic properties of MgH2 via Mo doping: Prospects and potential for clean energy hydrogen-storage fuel and optoelectronic applications

Abstract

With the increasing depletion of conventional energy sources and their detrimental environmental hazards, it is imperative to search for sustainable alternative clean energy sources. In the recent decades, hydrogen has emerged as potential source of clean energy. One of the potential alternatives to achieve the objective is the designing and characterization of materials for hydrogen-storage energy applications. In this regard, metal-bearing hydrides are the most promising candidates. For instance, magnesium-bearing hydrides are the focus of current research work owing to high hydrogen capacity of 7.6 wt%. In this paper, we first time report density functional-based quantum theoretical analysis to explore the potential of Mo-doped magnesium hydrides MgH2:Mo for optoelectronic and hydrogen-storage applications. For the quantum computations of the required optoelectronics and energy storage properties, we employed all-electron methods within generalized gradient approximation (GGA). Besides applying GGA approximation to account for the electronic correlated effects, we employed the Hubbard potential U (= 4 eV) for onsite repulsive Coulomb force. We predict that 10% doping by weight of Mo into MgH2 suppresses its insulating band gap of 4.9 eV to semiconducting band gap of order 3.15 eV for spin up and 0.15 eV for spin down. As such the doping of Mo can tune the the bandgap, structural, electronic and optoelectronic properties of MgH2 considerably for potential applications.