When these complex compounds are dispersed in dichloromethane in an ultrasonic bath for ten minutes, irregular micrometer length tubes of continuous crosslinked GO nanosheets can be easily separated and their structure can be very clearly observed by HR-TEM (Fig 4A and 4C). Besides, the lattice atoms of these continuous carbon materials crosslinked with divalent cations of Zn can be directly imaged (Fig 4B).