Fabrication of microporous GO-TiO2 membrane via an improved weak alkaline sol-gel method

Microporous graphene oxide (GO)-TiO2 membranes were successfully fabricated via an improved weak alkaline sol-gel route. Two-dimensional (2D) GO nanosheets were introduced into an alkaline catalyzed titania sol to form a crosslinked GO-TiO2 sol. Then the sol was directly dip-coated on a mesoporous support to transform into a toughened network-structured gel. SEM-EDX characterization indicated that sol infiltration could be effectively suppressed, benefiting from the GO nanosheets possessing a sufficiently large size in horizontal direction. Further, an integrated and crackless membrane layer with a thickness of 2 µm was formed after sintering at 400 °C. The results of thermogravimetric (TG) and the X-ray photoelectron spectroscopy (XPS) analysis showed that GO still remained at the sintering temperature, which helps to reduce the membrane pore size. The filtration of Polyethylene glycol (PEG) and UV-vis diffuse reflectance spectra tests revealed that the prepared membrane possessed a pore size of ~1.8 nm and a band gap energy of 2.73 eV, resulting in visible-light response microporous GO-TiO2 membranes that could be fabricated directly by the facile method.