Fig. 2: Construction of friction-differentiated nanochannels based on 2D niobate perovskite with highly crystalline interlayer conduits symmetrically assembled by niobate group.

a Typical atomic force microscopic image of the channel building block, monodisperse niobate perovskite (m-KN) nanosheet prepared by microfluidic liquid-phase exfoliation (MLPE) in 2 nm thick, corresponding to a zigzag assembled bilayer; representative of three independent samples. Scalebar: 1 μm. Inset: the aqueous dispersion of m-KN with a concentration of 3 mg/mL. b Thickness distribution of m-KN nanosheets, which is thinner and more regular than the polydisperse niobate perovskite (p-KN) without microfluidic assistance treatment. c Lateral size distribution of m-KN and p-KN. Thickness distribution measured from n = 100 individual nanosheets across 3 independent samples. Laterial size distribution measured from n = 100 individual nanosheets across 3 independent samples. d TEM images of m-KN nanosheets showing 2D characteristic morphology; representative of three independent regions. Scalebar: 1 μm. Inset: the atomic resolution TEM image of m-KN with orthorhombic cell, consistent with the simulating result (the green model). Scalebar: 2 nm. e Highly ordered stacking of m-KN on the cross-section view of its based membrane under the scanning electron microscopy (SEM) (scalebar: 2 μm); representative of three independent regions showing a transparent appearance (upper left, scalebar: 1 cm). f Wide-angle X-ray scattering (WAXS) pattern of m-KN based membrane (upper right) and its azimuthal angle plot. g SEM cross section view in p-KN based membrane (scalebar: 4 μm); representative of three independent regions and corresponding digital photo with glazed appearance (upper left, scalebar: 1 cm). h WAXS pattern of p-KN based membrane and its azimuthal angle plot. Source data of (a, b, c, f, h) are provided as a Source Data file.