First-principles study of triaxial strain effect on structural, mechanical, electronic, optical, and photocatalytic properties of K2SeBr6 for solar hydrogen production

Abstract

This study represents the first comprehensive investigation into the photocatalytic performance of the double halide perovskite K₂SeBr₆ for hydrogen production via water splitting, employing density functional theory (DFT) as implemented in WIEN2k. The research encompasses an in-depth analysis of the structural, elastic, electronic, optical, transport, and photocatalytic properties of K₂SeBr₆. The findings reveal that K₂SeBr₆ fulfills the thermodynamic prerequisites for driving the water-splitting reaction. However, its band edges are significantly far from the water redox potentials, resulting in slower reaction kinetics. To address this limitation, the study investigates the application of tensile triaxial strains (2 %, 4 %, and 6 %). Tensile strain application reduces the bandgap energy, shifts optical absorption into the visible spectrum, and enhances the kinetics of the photocatalytic reactions. Additionally, the influence of pH on the photocatalytic efficiency of K₂SeBr₆ was thoroughly examined. Beyond its application in water splitting, the study explores the potential of K₂SeBr₆ for detecting and reducing CO₂ into useful chemicals and fuels. These findings propose effective strategies for optimizing K₂SeBr₆ as a multifunctional material, particularly as an efficient photocatalyst for solar-driven hydrogen production.