GO powder containing single-layered laminates with a lateral size of ~500 nm (Jiangsu XFNANO Materials Tech. Co. Ltd) was dispersed in deionized water at the concentration of ~0.1 mg/mL. The GO suspension was then ultrasonicated for 2h under ambient conditions, avoiding GO reduction at elevated temperatures. GOMs were fabricated onto polyvinylidene fluoride (PVDF, 0.1 µm pore size) substrate by filtering 5 mL of GO suspension under vacuum at ~0.9 bar pressure, and the obtained GOMs were air-dried for 24 hours.