DFT investigation of the Si-As co-doped SrTiO₃ perovskite for hydrogen evolution via water splitting under UV-vis...

This study uses density functional theory (DFT) calculations combined with molecular dynamics (MD) simulations to evaluate the water-splitting performance of the SrTiO₃ perovskite improved through synergistic Si and As co-doping. While static DFT calculations capture only a single atomic configuration, MD simulations provide finite-temperature atomic ensembles, enabling realistic assessments of water adsorption, dissociation, and radical-formation processes. Pristine SrTiO₃ shows pronounced thermal fluctuations, indicating weak thermal management, likely caused by limited generation of charge carriers and their rapid recombination. In contrast, the Si-doped, As-doped, and especially Si-As co-doped systems achieve faster thermal stabilization, suggesting enhanced charge-carrier dynamics and improved photocatalytic activity. Electronic analysis reveals significant band-gap narrowing in the doped structures due to the introduction of dopant-induced electronic states near the conduction band, increasing charge-carrier mobility. The band-gap trend-pure (2.12 eV) > As-doped (1.47 eV) > Si-As co-doped (1.50 eV) > Si-doped (1.28 eV)-extends absorption toward 570 nm, enabling visible-light-driven photocatalytic activity that is not exhibited by pristine SrTiO₃. Overall, Si-As co-doping markedly enhances SrTiO₃'s water-splitting capability.