Controlling Thickness of Aurivillius Phase Perovskite Nanosheets Obtained by Delaminating Bi₂SrNa_n–2Nb_nO_3n+3 (n = 2–5) Layered Crystal

A monolayer Bi-doped SrNa n –2 Nb n O 3 n +1 2– ( n = 2, 3, 4, 5) nanosheet was obtained by delaminating an Aurivillius-phase layered perovskite Bi 2 SrNa n –2 Nb n O 3 n +3 . The thickness of the Bi-doped SrNa n -2 Nb n O 3 n +1 2– nanosheet was successfully controlled by changing the n values of the precursor layered crystals by using a simple calcination method. The mechanical property of the Bi-doped SrNa n –2 Nb n O 3 n +1 2– nanosheets was evaluated by comparing phase delay by AFM measurement, which indicated that the thicker perovskite crystal was more perpendicularly deformable. HAADF-STEM observation confirmed that the A site of the Bi-doped SrNa 2 Nb 4 O 13 2– perovskite nanosheet was partially occupied by Bi. EDS study also proved that 9–13% of the A site in the Bi-doped SrNa n –2 Nb n O 3 n +1 2– nanosheet was occupied with Bi. Further investigation on the crystal structure of the Bi-doped SrNa n –2 Nb n O 3 n +1 2– nanosheet was performed with in-plane XRD patterns, Raman spectra, and FE-SEM images. The band gap energy, flat-band potential, and photoelectrocatalytic activity for oxidation of methanol were studied with (photo)electrochemical measurements and correlated to the number of n values.