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 sp(2) 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.