Application of Atomic Force Microscopy Characterization Technology in MgAl-CO32--LDH Exfoliation Behavior

MgAl-CO32--LDH was exfoliated via two-step ultrasonic treatment in formamide. Atomic force microscopy (AFM) was employed to characterize the thickness variation of MgAl-CO32--LDH during exfoliation. MgAl-CO32--LDH was dispersed in formamide with continuous ultrasonic treatment for 4 h, getting a non-transparent turbid liquid. The non-transparent turbid liquid was laid aside one day and separated into two phases, the upper semi-translucent colloidal suspension containing partial exfoliated MgAl-CO32--LDH was dispersed in formamide with continuous ultrasonic treatment again. The AFM results reveal that the thickness of pristine MgAl-CO32--LDH is 250 nm while the MgAl-CO32--LDH nanosheet obtained from the first-step ultrasonic treatment is 90 nm with obvious transverse sliding. The thickness of MgAl-CO32--LDH nanosheet obtained after the second-step ultrasonic treatment is about 7 nm, which is almost in agreement with the theoretical thickness of 10 monolayers of MgAl-CO32--LDH (0.76 nm).