To assess the effectiveness of surface modification, we used SEM to characterize the TiO2–GO membrane and also two control membranes that were obtained by modifying the PSf base mem- branes with GO and TiO2, respectively. It is observed in Fig. 5(a) that the surface of the GO-modified membrane was partially covered by GO nanosheets, with some darker areas still showing the bare surface of PSf that had a pore size in the tens of nanometer range. In comparison, the TiO2-modified membrane had a large number of TiO2 nanoparticles and aggregates on the surface (Fig. 5(b)), while the TiO2–GO membrane had a very similar surface morphology to that of the TiO2-modified membrane except that fabric-like features created by GO nanosheets (pointed by arrows in Fig. 5(c)) can be clearly observed.