One-step synthesis of open-cell Ni foams by annealing the Ni2+-based precursor in air

In this paper, we present a facile approach to fabricate open-cell Ni foams by annealing the colloid of Ni(NO3)(2) and 2-methoxyethanol (C3H8O2) in air. X-Ray diffraction and selected area electron diffraction results show that the products are single crystal Ni in the face-centered cubic (fcc) phase. This result was confirmed by the peak corresponding to zero valence of Ni in X-ray photoelectron spectroscopy. Scanning electron microscopy results reveal the 3-dimensional geometry open-cell foam structure of the products. The average aperture size of the Ni foam is about 300 nm and the wall stent is about 250 nm with an Ni2+ concentration of 0.35 M in the colloid. The porosity of the products decreases gradually with increasing Ni2+ concentration in C3H8O2. Owing to its uniform 3-D structure with high porosity and high specific surface area, the open cell Ni foams may have some potential applications, such as magnetic flux conductors or an ideal electrode material for high energy MH/Ni and Cd/Ni batteries, etc.