Strain Induced Optoelectronic, Thermal, and Photocatalytic Activity of the Double Perovskite Oxide Sr 2 InOsO 6 With Os‐5d Transition Metal Oxides for Spintronic Devices: A GGA and GGA + mBJ First‐Principles Comparative Analysis

ABSTRACT The increasing global energy demand and the inherent nature of conventional electronic devices and power conversion systems point to the need for the development of advanced energy materials with a clear focus on sustainability. In this work we examine the structural, electronic, optical, thermal and photocatalytic properties of double perovskite oxide Sr 2 InOsO 6 strongly correlated Os‐5d electrons using the GGA, GGA+mBJ, GGA+U, GGA+U+mBJ correlation method with and without spin orbital coupling (SOC) and applying strain engineering these are implemented within DFT based WIEN2K code. GGA without SOC show metallic or semiconducting behavior underestimate band gap 0.24–0 eV with biaxial strain −1%, 5%. GGA+mBJ show semiconductor behavior band gap 2.31–1.38 eV with biaxial strain 1%, −5%. Exchange interactions in the Os‐5d orbitals, indicating intrinsic magnetic ordering in Sr 2 InOsO 6 . Additionally optical and transport properties including dielectric function, refractive index, absorption coefficient, extinction coefficient, reflectivity, electrical conductivity, Seebeck coefficient, power factor, specific heat capacity, thermal conductivity have been evaluated. Observing the photocatalytic properties CB −5.27 eV which is below the H + /H 2 potential −4.44 eV, Sr 2 InOsO 6 is suitable for OER photocatalyst. These results highlight Sr 2 InOsO 6 as a viable option for advanced optoelectronics, and sustainable OER Z‐scheme photocatalytic systems.