Controlling Thickness of Aurivillius Phase Perovskite Nanosheets Obtained by Delaminating Bi2SrNa n-2Nb n O3n+3 (n=2-5) Layered Crystal

A monolayer Bi-doped SrNan-2NbnO3n+12- (n = 2, 3, 4, 5) nanosheet was obtained by delaminating an Aurivillius-phase layered perovskite Bi2SrNan-2NbnO3n+3. The thickness of the Bi-doped SrNan-2NbnO3n+12- 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 SrNan-2NbnO3n+12- 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 SrNa2Nb4O132- perovskite nanosheet was partially occupied by Bi. EDS study also proved that 9-13% of the A site in the Bi-doped SrNan-2NbnO3n+12- nanosheet was occupied with Bi. Further investigation on the crystal structure of the Bi-doped SrNan-2NbnO3n+12- 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.