Selective Enhancement of Photo-Piezocatalytic Performance in BaTiO₃ Via heterovalent Ion Doping

This study proposes a strategy based on heterovalent ion doping that gives rise to a synergistic piezo-phototronic effect with significantly improved catalytic activity and leads to selective catalytic enhancement for specific pollutants. Owing to the enhanced light absorption, hydrogen evolution rates are as high as 3704 and 3178 µmolg⁻¹ h⁻¹ in 0.01Li-doped BaTiO₃ and 0.02La-doped BaTiO₃ nanosheets, respectively, under simultaneous irradiation by ultrasound and light, a factor of 4.6 and 3.9 times higher than for pure BaTiO₃. The performance also far exceeds that of single piezocatalysis, photocatalysis, or the sum of the two for Li/La-doped BaTiO₃ nanosheets due to the effects of the piezoelectric field in promoting photo-induced separation of electron-hole pairs. Further, by carefully selecting donor or acceptor doping, a significant enhancement in catalyst to specific pollutants is obtained by controlling the band structure. Compared to pure BaTiO₃, 0.01Li-doped BaTiO₃ possesses higher catalytic activity for anionic dyes such as Methyl blue and Malachite Green, reaching 0.067 and 1.379 min⁻¹, respectively, while 0.02La-doped BaTiO₃ exhibits better catalytic performance for cationic dyes such as Rhodamine B and Methyl Orange, with degradation rates up to 0.274 and 0.029 min⁻¹, respectively. This study offers a path to the design of efficient piezocatalysts for specific applications.