Femtosecond Laser Fabrication Of Photothermal And Superhydrophilic Surfaces And The Applications

Wettability is ubiquitous in life,and it is a very common phenomenon in nature.The research on special wettability can effectively solve some bottleneck problems that people are facing at present,such as oil-water separation,fog collection and so on.Photothermal conversion is a simple and effective method to utilize solar energy.By continuously developing new photothermal materials or devices,many functions have been realized by photothermal effect.The combination of photothermal and wettability is a new exploration of multifunctional materials,which will contribute to the development of more applications.Superhydrophilicity,as a common special wettability,the combination with photothermal effect has attracted wide attention from researchers in recent years.At present,people have fabricated different photothermal and superhydrophilic surfaces by various methods,but most of them show problems such as long preparation time,environmental pollution or cumbersome steps.Femtosecond laser processing technology,as a simple processing method,can modify the material surface quickly and without pollution,showing many advantages in the field of material processing.In this paper,two kinds of materials with photothermal and superhydrophilic surface were prepared by femtosecond laser micro-nano processing technology,which realized the water droplet rapid spreading transport and efficient water evaporation driven by solar energy.The specific work contents are as follows:（1）The surface with photothermal and superhydrophilic properties was fabricated by femtosecond laser ablation of stainless steel.Utilizing the ability of photothermal surface to absorb light into heat,the prepared superhydrophilic stainless steel surface realized the water droplet rapid spreading transport.Compared with the pristine stainless steel surface and the laser treated stainless steel surface at room temperature,it showed faster water droplet transportation speed（about twice）.The mechanism was revealed that the temperature will affect the viscosity of water droplet and the evaporation at the same time,and the optimal temperature of water droplet spreading transport should consider them comprehensively.（2）Using copper foam as raw material,the photothermal and superhydrophilic structures was constructed on its surface by one-step femtosecond laser processing.An efficient water evaporation strategy based on the evaporator constructed by laser processing copper foam combined with solar fan was proposed,and a high-performance solar water evaporation system was established.The water vapor generation rates of the evaporation system in various simulated conditions and actual environment were explored,and the high-efficiency water evaporators proposed in many literatures were compared,which shows that the evaporation system has a high water evaporation rate(7.64 kg·m^-2·h^-1).