Two-phase Cu-Ni magnetic metallic foams (MMFs) with tunable composition have been prepared by electrodeposition taking advantage of hydrogen co-evolution as a source of porosity. It is observed that Ni tends to deposit inside the porous network defined by the Cu building blocks. Contact angle measurements reveal that the prepared porous films show a remarkable superhydrophobicity (contact angle values larger than 150°) and a non-sticking property to aqueous droplets. This behavior is predominately ascribed to the morphology of the films - hierarchical micro/nanoporosity, wall thickness, and spatial arrangement. The electrochemical activity and stability towards hydrogen evolution reaction of the Cu-Ni MMFs has been investigated by cyclic voltammetry in 1 M KOH at 298 K, and the optimal Ni content is found to be 15 at%. Furthermore, all the foam-like films exhibit ferromagnetic behaviour due to the presence of the Ni-rich phase, with coercivity values ranging from 114 Oe to 300 Oe. From the technological point of view, the Cu-Ni MMFs are promising candidates for magnetically-actuated micro/nano-electromechanical systems (MEMS/NEMS) and micro/nanorobotic platforms with a large surface-area to volume ratio or in magnetic sensors or separators.

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A versatile chemical synthesis procedure to obtain Al2O3 and Co2FeO4 nanolayers conformally coating a three-dimensional (3D) porous Ni film is presented. First, porous Ni is grown by hydrogen bubble template-assisted electrodeposition. Subsequently, Al2O3 and Co2FeO4 layers, with thickness ranging from 5 nm to 25 nm, are directly deposited onto the pore walls by atomic layer deposition, while maintaining the porous architecture and magnetic properties of the Ni scaffold. The crystal structure, thickness and distribution of elements within the composite coatings are investigated in detail. The resulting magnetic and wettability properties are assessed. Contact angle tests reveal that 3D porous Ni films become more hydrophilic after coating with Al2O3 or Co2FeO4. From a technological point of view, the obtained composite porous films could be appealing for applications like magnetically-actuated micro/nano-electromechanical systems (MEMS/NEMS) or bio-MEMS/NEMS, among others.

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