Facile and environmentally-friendly fabrication of underwater superaerophobic and superaerophilic metallic surfaces through laser ablation and heat treatment

Abstract Underwater superaerophilic and superaerophobic metallic surfaces have gained increasing interest due to their significance in both academic research and industrial applications. However, surface chemical modifications with low-surface-energy reagents are usually demanded to fabricate the underwater superaerophilic metallic surfaces, which would increase production cost, operation difficulty, and environmental risk. In this work, we developed a facile and environmentally-friendly method to fabricate underwater superaerophobic and superaerophilic surfaces on aluminum, H59 brass, 304 stainless steel, and titanium substrates through laser ablation and low-temperature heat treatment. After the laser ablation, the metallic surfaces exhibited underwater superaerophobicity since the great affinity of the surfaces with water makes the gaps of the micro/nano structure be filled with water, which repels the bubbles in water. While, after the heat treatment, the laser ablated metallic surfaces became underwater superaerophilic because the hydrophobic airborne organic compounds adsorbed on the laser ablated metallic surfaces prevent water entering into the roughness grooves and make the gaps of the micro/nano structure be occupied by air, which can absorb the bubbles in water. Additionally, it was demonstrated that such underwater superaerophobic and superaerophilic metallic surfaces can be used to control the passage of the underwater bubbles by combining with fabricating the micro-holes structure.