Computational Investigation for Tetragonal Crystals of Zn(GaS2)2, Zn(GaSe2)2, and Zn(GaTe2)2 Photocatalysts for Wastewater Treatment: First Principle Approaches

In pursuit of advancing the field of photocatalysis, a comprehensive investigation was undertaken to elucidate the electronic structure, structural geometry, and optical characteristics of Zn(GaS2)2, Zn(GaSe2)2, and Zn(GaTe2)2, followed by a comparative analysis of these properties. Initial explorations involved the employment of four distinct Density Functional Theory (DFT) functionals, specifically the Generalized Gradient Approximation (GGA) with Perdew-Burke-Ernzerhof (PBE), GGA with Revised Perdew-Burke-Ernzerhof (RPBE), GGA with Perdew-Wang 1991 (PW91), and GGA with Wu-Cohen (WC) functionals, to conduct a preliminary assessment of the electronic band structures and structural configurations of the crystalline materials. However, it was noted that the band gap values for Zn(GaS2)2 exhibited variations across the different DFT functionals, registering at 2.068 eV for GGA-PBE, 2.214 eV for GGA-RPBE, 2.033 eV for GGA-PW91, and 1.936 eV for GGA-WC, where the latter value of 1.936 eV closely approximated the reference value of 1.93 eV. Consequently, the GGA-WC method emerged as the most accurate and reliable functional among the evaluated options. Furthermore, the band gap values for Zn(GaSe2)2 and Zn(GaTe2)2 were determined to be 1.726 eV and 0.329 eV, respectively, utilizing the GGA-WC functional. The total electron density was meticulously examined to delineate potential electron localization sites within the crystals, particularly concerning their capacity to activate or bond with environmental pollutants, thereby serving as efficient photocatalysts. Conspicuously, Zn(GaTe2)2 has emerged as a distinguished contender, showcasing remarkable photocatalytic effectiveness in wastewater treatment, outperforming its fellow materials. This revelation harbors substantial potential for propelling advancements in the realm of photocatalysis and environmental remediation.