Numerical Simulation and Evaluation of Y\(_2\)S\(_3\) and Y\(_2\)TeS\(_2\) on Structural, Stability, and Electronic Properties for Photocatalytic Water Splitting Applications

Abstract

We attempt to establish a computational insight into the structural, mechanical, dynamic, electronic, and photocatalytic properties of orthorhombic phase Yttrium sulphide Y\(_2\)S\(_3\) and Y\(_2\)TeS\(_2\) Janus compounds by density functional calculations. The Janus Y\(_2\)TeS\(_2\) is a hypothetical compound with all properties computed forthe first time. Computed lattice parameters for Y\(_2\)S\(_3\) are in reasonable agreement with available experimental data. Mechanical properties are investigated by calculating the elastic constant to check for Born stability criteria. A finite displacement vibrational frequency study confirmed that Y\(_2\)S\(_3\) and Y\(_2\)TeS\(_2\) are stable; negative phonon frequencies were checked. Computed PBEsol and MBJ band structures found that Y\(_2\)S\(_3\) is a direct band gap semiconductor, while Y\(_2\)TeS\(_2\) is an indirect band gap semiconductor. Band gaps estimated from the HSE06 hybrid functional are 2.75 eV and 2.70 eV for Y2S2 and Y\(_2\)TeS\(_2\), respectively, suggesting that they are semiconductor materials with wide band gaps that can absorb light in the ultraviolet region. Mullikan’s electronegativity screen technique, used to calculate valence band maximum VBM and conduction band minimum CBM potentials, predicted that Y2S3 and Y\(_2\)TeS\(_2\) have suitable conduction band minimum potential of -1.05 V and -1.30 V and valence band maximum of 1.70 V and 1.40 V, respectively, versus normal hydrogen electrode (NHE) at PH = 0 to trigger the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) simultaneously.