Comparative studies of Ag3PO4, Ag2CO3, and Ag3VO4 as photocatalyst for wastewater treatment: A first-principles calculation

This study delves into the realm of photocatalysis, seeking to enhance our comprehension by conducting a thorough examination of the electronic structure, structural geometry, and optical properties exhibited by a selection of silver-based compounds. The materials under scrutiny in this investigation include Ag₃PO₄, Ag₂CO₃, and Ag₃VO₄. The investigation commenced with an analysis of five DFT functionals - GGA with PBE, GGA with RPBE, GGA with PBEsol, GGA with PW₉₁, and GGA with WC-to preliminarily evaluate the electronic band structure and structural geometry of these predicted crystals. The principal aim revolved around the elucidation of the band structures characterizing these selected crystalline materials, employing a suite of five distinct Generalized Gradient Approximation (GGA) functionals, as previously elucidated. Notably, the band gap value determined for Ag₂CO₃ was established at 0.485 eV when employing the GGA-PBE functional, a result that exhibited an exceptional proximity to the reference value of 0.470 eV. As a corollary, the GGA-PBE method emerged as the preeminent and most precise computational technique among those considered for the examination of these specific compounds. Secondly, the Density of States (DOS) and Partial Density of States (PDOS), evaluated for emphasizing the atomic orbital contributions. Furthermore, six optical properties - absorption, reflection, refractive index, conductivity, dielectric function, and loss function - were dissected to offer deeper optical insights with comparative exploration. Last, crystals' mobility by calculating the effective mass of electrons and holes, as well as the reduced effective electron mass examined for predicting electronic transition to conveying photo catalytic behavior of crystals. However, the band gap of Ag₂CO₃ is much lower than other crystals (Ag₃PO_4, Ag₃VO₄ (Tetragonal) and Ag₃VO₄) even it is similar trend for effective masses for electrons (0.4174) and holes (0.85985) as well as reduced effective masses (0.8112). However, Ag₂CO₃ is more effective photo catalytic agent, meaning carbonate (^--CO₃) group acts more convenient with silver metal as photo catalytic activities.