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

Ultrathin nitrogen-doped perovskite nanosheets LaTa2 O6.77 N0.15 - have been fabricated by exfoliating Dion-Jacobson-type layered perovskite RbLaTa2 O6.77 N0.15 . 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 (λ ≥ 420 nm) approaches 1.29% and 3.27% for photocatalytic hydrogen and oxygen production, being almost 4-fold and 8-fold higher than bulk RbLaTa2 O6.77 N0.15 . 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 RbLaTa2 O6.77 N0.15 ; thus, exfoliating RbLaTa2 O6.77 N0.15 into LaTa2 O6.77 N0.15 - nanosheets has limited impact on charge transportation properties but significantly enhances the surface areas which contributes to more reaction sites.