SrTaO2N co-doped with La/Zr as promising photocatalysts for water reduction under visible light illumination

Abstract

La/Zr co-doped SrTaO₂N has been investigated as visible-light-active photocatalysts for water reduction. Unlike previous aliovalent doping that leads to a decrease in light absorption, La/Zr co-doping largely preserves the visible light absorption of SrTaO₂N. More importantly, the La/Zr co-doping not only helps to improve surface hydrophilicity and reduce particle sizes but also effectively inhibits defect formation (e.g. Ta⁴⁺) in SrTaO₂N. These modifications are responsible for significant enhancements in photocatalytic H₂ production. AQE as high as 0.84% was achieved at 420 ± 20 nm for Sr_0.4La_0.6Ta_0.4Zr_0.6O₂N (x = 0.6), which also showed good durability and stability. Further analysis suggests that La/Zr co-doping negatively shifts the conduction band edge positions of SrTaO₂N and contributes to better charge separation conditions.