Boosting visible-light-driven water splitting over LaTaON2via Al doping

LaTaON 2 is an attractive visible-light-active photocatalyst for water splitting due to its broad visible light absorption as far as 650 nm and proper band edge positions. Notwithstanding these promising properties, LaTaON 2 generally exhibits poor photocatalytic activity because of its high defect concentration that severely hinders charge separation. Here, LaTaON 2 has been modified by doping Al into the Ta sublattice, i.e., LaTa 1− x Al x O 1− y N 2− y (0 ≤ x ≤ 0.20). Al doping not only inhibits the defect concentration and increases surface hydrophilicity but also maintains the desired visible light absorption of LaTaON 2 . These important modifications substantially ameliorate the charge separation conditions within LaTaON 2 and are responsible for a much enhanced photocatalytic performance for water redox reactions under visible light illumination. Under optimal conditions, the Al-doped LaTaON 2 delivers an apparent quantum efficiency of 1.17% at 420 ± 20 nm for water oxidation into O 2 , outperforming most LaTaON 2 -based photocatalysts. These findings highlight Al as a useful dopant to open up the photocatalytic potential of metal oxynitrides whose activity is often undermined by a high defect concentration.