Lattice distortion-driven band gap engineering and enhanced electrocatalytic activity of Mn-substituted...

The lattice distortion and electrocatalytic activity are investigated by the mono-substituent of Mn with different concentrations to generate localized states in the electronic structure of SrTiO₃. The sol-gel approach has been employed to fabricate SrTiO₃ and SrTi_1-xMn_xO₃ nanostructures (NSs). The structural analysis indicates Mn incorporation into Ti sites of SrTiO₃, which shifts the lattice towards a higher diffraction angle with a single-phase cubic structure. The optical absorption spectra exhibit a decrease in band gap from 3.27 to 1.89 eV and reveal the shift in band edge positions towards the visible region. XPS analysis is carried out to confirm the formation of oxygen vacancies and valence band edge position. For SrTi_0.88Mn_0.12O₃, OER and HER have the overpotential of 445 and 157 mV at a current density of 100 and 10 mA cm^-2. Hence, the substitution of Mn (x = 0.12) into SrTiO₃ lattice results in lattice distortion that enhances the electrochemical performance compared to SrTiO₃. The current work manifestly established the optimal Mn composition (x = 0.12) in SrTiO₃ lattice as desirable materials with defective valence states for required electrocatalytic redox potential as well as the acceleration of charge transfer kinetics towards water splitting applications.