images were acquired by an Asylum Research MFP-3D Origin AFM (Oxford
Instruments, U.K.). The instrument was operated in tapping mode and
equipped with a silicon cantilever (AC240TS-R3, k = 1.3 N·m–1) with a nominal tip radius of
∼7 nm. Gwyddion56 (link) and Mountains
8 (Digital Surf, France) software was used to process and analyze
the AFM topography images.