DFT-based screening of Cu2ZnSn(Se1-xSx)4 semiconductors for gas adsorption and photocatalytic applications in cement-industry pollutants

Abstract

In this study, Cu 2 ZnSn(Se 1-x S x ) 4 (CZTSSe) semiconductors are investigated as a composition-dependent first-principles screening platform for pollutant adsorption and photocatalytic-related electronic properties relevant to cement-industry emissions. Density functional theory (DFT) calculations were performed for four compositions: Cu 2 ZnSnSe 4 , Cu 2 ZnSn(Se 0.75 S 0.25 ) 4 , Cu 2 ZnSn(Se 0.50 S 0.50 ) 4 , and Cu 2 ZnSn(Se 0.25 S 0.75 ) 4 . Structural, electronic, density-of-states (DOS/PDOS), optical, effective-mass, mechanical, and adsorption properties were evaluated using a consistent computational setup. The calculated PBE band gap decreases from 1.515 eV for Cu 2 ZnSnSe 4 to 1.281 eV for Cu 2 ZnSn(Se 0.25 S 0.75 ) 4 , indicating that Se/S substitution can tune the electronic structure and associated optical response. The calculated adsorption energies show stronger relative interactions for CO 2 and SO 2 than for CO within the adopted adsorption model, with the strongest CO 2 and SO 2 interactions obtained for Cu 2 ZnSnSe 4 . The effective masses are used only as descriptors of band curvature, while the elastic calculations are interpreted in terms of the theoretical mechanical stability of the idealized structures. These results provide composition-dependent computational trends that can guide subsequent experimental and mechanistic studies. The calculations do not by themselves establish adsorption capacity, pollutant-removal efficiency, photocatalytic efficiency, carrier mobility, regeneration behavior, or long-term industrial stability.