Boosting visible-light-driven water splitting over LaTaON2 via Al doping

LaTaON2 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, LaTaON2 generally exhibits poor photocatalytic activity because of its high defect concentration that severely hinders charge separation. Here, LaTaON2 has been modified by doping Al into the Ta sublattice, i.e., LaTa1-xAlxO1-yN2-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 LaTaON2. These important modifications substantially ameliorate the charge separation conditions within LaTaON2 and are responsible for a much enhanced photocatalytic performance for water redox reactions under visible light illumination. Under optimal conditions, the Al-doped LaTaON2 delivers an apparent quantum efficiency of 1.17% at 420 +/- 20 nm for water oxidation into O-2, outperforming most LaTaON2-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.

Automated summary

Doping aluminum into LaTaON2 improves its photocatalytic performance by enhancing charge separation conditions and surface hydrophilicity, leading to more efficient water splitting under visible light illumination.