RESUMO
Coral-like porous Si was fabricated through the dealloying of a laser remelted as-cast AlSi12 alloy(Al-12 wt % Si). The porous Si was composed of interconnected micro-sized Si dendrites and micro/nanopores, and compared to flaky Si, which is fabricated by direct dealloying of the as-cast AlSi12 alloy. The structure of the porous Si was attributed to the dendritic solidification microstructure formed during the laser remelting process. The micropore size of the porous Si decreased from 4.2 µm to 1.6 µm with the increase in laser scanning velocity, indicating that the morphology of porous Si could be easily altered by simply controlling the laser remelting parameters. The coral-like porous Si provided enough space, making it promising for high-performance Si-based composite anode materials in lithium-ion batteries. The proposed hybrid method provides a straightforward way of tuning the porous structure in the dealloyed material.
RESUMO
The fabrication of nanoporous anatase TiO2 on a microstructured Ti base is achieved through an innovative hybrid fabrication method involving femtosecond laser ablation coupled with H2O2 oxidation and annealing. The anatase TiO2 micro-nanostructures have superior photocatalytic degradation of methyl orange due to enhanced light harvesting capacity and surface area. The photodegradation efficiency increases by a maximum of 80% compared to the nanoporous anatase TiO2 fabricated through H2O2 oxidation and annealing only (without femtosecond laser ablation). Meanwhile, The anatase TiO2 micro-nanostructures show good cyclic performance, indicating a great potential for practical application. The proposed hybrid method can easily tune the morphology and size of microstructure by simply adjusting the femtosecond laser parameters, showing advantage in fabricating of micro-nanostructures with a rich variety of morphologies.
