Surface micro-nano structures show excellent properties such as wettability control (hydrophilic, hydrophobic), optical property control, micro-nano tribology, hydrodynamic/aerodynamic property control, cell adhesion and adhesion control, which is one of the frontier topics in nano science and technology research. We developed a hybrid approach including laser deposition, laser ablation and chemical dealloying for fabricating tunable micro-nano hierarchical Cu structure on engineering substrate surface. The structure consists of micro bumps with a width of 50 µm and a height of 100 µm, and nanoporous structures with a size of 70-150 nm on the micro bumps. The morphology of micro and nano structure can be tunable through the parameters of laser ablation and chemical dealloying. XRD and XPS results confirm that these hierarchical structures were made of Cu2O.
This hierarchical structure shows the best photo degradation of methyl orange under the visible light, whose photo degradation ratio is 78%, compared to the milliscale, microscale, and nanoscale structure counterparts. The influences on the photo degradation were discussed, such as concentration of the methyl orange, pH, and so on. The reaction kinetics and mechanism of the photo degradation are explained to be attributed to the Cu2O p-type semiconductor property, the energy difference and the high absorption of the light due to its micro-nano structure. The reported results demonstrate a good application example of surface micro-nano structure fabricated by hybrid laser approach.