Ultrathin Lanthanum Tantalate Perovskite Nanosheets Modified by Nitrogen Doping for Efficient Photocatalytic Water Splitting

Ultrathin nitrogen-doped perovskite nanosheets LaTa2O6.77N0.15- have been fabricated by exfoliating Dion-Jacobson-type layered perovskite RbLaTa2O6.77N0.15. These nanosheets demonstrate superior photocatalytic activities for water splitting into hydrogen and oxygen and remain active with photon wavelengths as far as 600 nm. Their apparent quantum efficiency under visible-light illumination (lambda >= 420 nm) approaches 1.29% and 3.27% for photocatalytic hydrogen and oxygen production, being, almost 4-fold and 8-fold higher than bulk RbLaTa2O6.77N0.15. Their outstanding performance likely stems from their tiny thickness (single perovskite slab) that essentially removes bulk charge diffusion steps and extends the lifetime of photogenerated charges. Theoretical calculations reveal a peculiar 2D charge transportation phenomenon in RbLaTa2O6.77N0.15; thus, exfoliating RbLaTa2O6.77N0.15 into LaTa2O6.77N0.15- nanosheets has limited impact on charge transportation properties but significantly enhances the surface areas which contributes to more reaction sites.