Visible Light-Driven Photocatalysis of Al-Doped SrTiO₃: Experimental and DFT Study

Environmental problems associated with water pollution caused by organic dyes have raised serious concerns. In this context, photocatalytic processes have proven to be promising and environmentally friendly methods for water purification utilising abundant solar energy. In this study, a SrTiO₃-based photocatalyst was modified by doping with Al ions and the deposition of dual co-catalysts (Rh/Cr₂O₃ and CoOOH) to enhance the photocatalytic decomposition efficiency of methylene blue (MB). Pure perovskite SrTiO₃ was synthesised by chemical precipitation followed by calcination at 1100 °C. Al-doped SrTiO₃ with deposited co-catalysts showed 3.2 times higher photocatalytic activity compared to unalloyed SrTiO₃ with co-catalysts in MB decomposition under visible radiation. This study highlights the effectiveness of using dual co-catalysts and low-valence metal doping to enhance the efficiency of the photocatalytic decomposition of organic pollutants. The density functional theory analysis results show that the Al doping of SrTiO₃ improves charge separation and increases the lifetime of photogenerated electrons and holes while maintaining the size of the forbidden band, which confirms its effectiveness for enhancing photocatalytic activity.