Surfaces with underwater superoleophobicity are critical for gravity-driven oil/water separation. Here, superwetting copper mesh membranes covered by ZnO nanostructures were successfully prepared via effective atomic layer deposition followed by a low-temperature hydrothermal process. The nanostructures evolved from one-dimensional nanowires (NWs) to a transition state and then two-dimensional nanosheets (NSs) were successfully fabricated on copper mesh membranes by changing the inhibitor concentration. The surface morphology, composition, wetting behavior and roughness of the membranes were characterized by SEM, energy-dispersive X-ray spectroscopy (EDS), contact angle (CA) and atomic force microscopy (AFM), respectively. The membranes with ZnO NWs were applied for separation of oil/water mixture and exhibited a high separation efficiency (> 99.7%) and flux (4.0 x 10(5) Lm(-2)h(-1)). Moreover, the NW membrane also showed good stability and reusability under corrosive conditions. The results suggest that ZnO NW membranes were a cost-effective and green approach with potential for practical oil/water separation applications.