Zr doped mesoporous LaTaON2 for efficient photocatalytic water splitting

In spite of strong visible light absorption and ideal band edge positions, LaTaON2 normally has very poor photocatalytic activity under ordinary conditions. Previous modifications of LaTaON2 such as aliovalent doping generally lead to strong reduction of its visible light absorption, being unfavorable for solar energy harvesting. Here, we introduce Zr into the structure of LaTaON2 (i.e. LaTa1-xZrxO1+yN2-y (0 x 0.15)) and successfully improve its photocatalytic activities without sacrificing its light absorption capability. More importantly, Zr doping helps to reduce Ta4+ defect concentration, improve surface hydrophilicity and induce mesoporous microstructures in LaTaON2, all of which contribute to the superior photocatalytic activities for water splitting reactions. Apparent quantum efficiency as high as 0.93% at 420 +/- 20 nm has been achieved on LaTa0.9Zr0.1O1+yN2-y (x = 0.10) for photocatalytic water oxidation reactions, being the highest AQE reported for LaTaON2 to date. Further photoelectrochemical analysis suggests that Zr doped LaTaON2 has better charge separation conditions, smaller interfacial charge transfer resistance and longer electron lifetime compared to pristine LaTaON2. This simple method using Zr as a dopant can be well extended to other perovskite oxynitrides.