Enhanced photocatalytic performance of SrTiO₃ crystals with (100), (110) and (111) orientations treated by N₂ (H₂) plasma

The nitrogen/hydrogen (N₂/H₂) plasma-treated strontium titanate (SrTiO₃) crystals with different orientations of (111), (110) and (100) were obtained using microwave plasma chemical vapor deposition, which was proved to be a simple and effective strategy to fundamentally improve the photocatalytic performance. It is found that plasma-treated SrTiO₃ crystals exhibit different photocatalytic properties in relation to crystalline anisotropy, plasma types and microwave power. The N: SrTiO₃ samples display higher photocatalytic activity compared to the untreated sample and N₂/H₂-treated sample. The (111) N: SrTiO₃ which is treated using N₂ plasma of 600 W shows the best photocatalytic performance in the current research. The dopants of nitrogen can serve as electron donors, which introduce impurity states in various positions in the band gap of SrTiO₃ and lead to different degrees of modification in electrical conductivity. The enhancement for photocatalytic properties and the effects of N₂ plasma treatment on the charge separation and transfer efficiency will be discussed.