Facile fabrication of super-hydrophilic porous graphene with ultra-fast spreading feature and capillary effect by direct laser writing

This study demonstrated a facile method to fabricate super-hydrophilic 3D porous graphene with high capillary force and ultra-fast spreading characteristic by direct laser writing on KMnO4-coated polyimide (PI) films. Highly oxidized laser-induced graphene (OLIG) was obtained with dominated sp2 carbon referring from Raman spectroscopy and X-ray diffraction. In addition, abundant oxygen functional groups and a 3D porous scaffold structure with foam-like flakes were produced based on the results of X-ray photoelectron pattern and scanning electron microscopy. OLIG showed ultra-fast spreading properties that water drops can spread completely within dozens of milliseconds. The morphology and chemical composition also render the new material with good capillary effect. The capillary rate-of-rise test with IR camera demonstrated that the wetted height of OLIG strip can reach around 16 mm within 5 min. [Display omitted] •Super-hydrophilic graphene with porous structure was fabricated from KMnO4-painting polyimide film by CO2 laser.•Massive pores and hydrophilic functional groups were induced due to the strong chemical between KMnO4 and carbon.•The chemical composition was mainly consisted of sp2 carbon.•Water drops can spread completely on the surface within dozens of milliseconds and good capillary effect can be observed.