Biaxial strain engineering of Sn1−xTixO2: Insights into structural, electronic, and transport properties with photocatalytic potential

In this study, the viability of band gap engineering enabled by the progressive substitution of titanium within the Sn 1 − x Ti x O 2 semiconducting alloy framework, is systematically examined. Potentially stable ternary compounds were primarily selected by means of an evolutionary algorithm to explore the free energy surface in conjunction with first-principles calculations. Consequently, a tetragonal phase featuring four distinct chemical compositions was predicted. The findings underscore the profound and consistent impact of titanium on the thermodynamic stability of these compounds, which exhibit an inherent structural resilience, permitting strain accommodation without experiencing phase transitions. Notably, an alloy composition of x = 0 . 5 reveals the most significant resistance to compression, as evidenced by the increase in the bulk modulus. With respect to photocatalytic properties, the band gap is observed to decrease as the magnitude of the applied biaxial strain increases, concomitant with a reduction in Ti concentration. Through the advancement of substitution, the compounds demonstrate the capability to promote the photolytic dissociation of water into hydrogen and oxygen, as indicated by the alignment of both the conduction band minimum and valence band maximum with the electrochemical redox potentials relevant to water.