Control of the wettability of graphene oxide surface with femtosecond laser irradiation (Invited)

Modification of material surface morphology and properties based on femtosecond laser irradiation is a novel processing technology developed in recent years, which has shown unique advantages in high-speed, large-area and periodic subwavelength structure fabrications. Here this method was employed to rapidly fabricate uniform subwavelength grating structures on the surface of GO film, and then the processing mechanisms, the change of morphology and liquid wettability were investigated comprehensively. Through using different experimental parameters such as the laser power and the scanning speed, the rGO grating structures with variable depth-width ratios and surface "roughness" were obtained, leading to the controllable wettability with the liquid contact angles in a range of 15° to 75°, and their contact angles were found to increase by an average of 20° after 20 days in the air. Our work lays a solid foundation for femtosecond laser micro/nano-processing of two-dimensional materials. It is expected to have the future applications in the field of droplet collection, microfluidic control, and so on.