Determination of reversible hydrogen adsorption site in Ni-nanoparticle-dispersed amorphous silica for hydrogenseparation at high temperature

The reversible hydrogen adsorption site in Ni-nanoparticle-dispersed amorphous silica (Si-O) was identified by analyzing the hydrogen adsorption behavior and the microstructure. The total amount of reversibly adsorbed hydrogen was evaluated from the total surface area of Ni and the Ni concentration in the composite. The total surface area of the Ni nanoparticles in each sample powder was calculated from the mean particle size of the Ni nanoparticles in the Si-O matrix using dark field images taken by transmission electron microscopy and high-angle annular dark-field images by scanning transmission electron microscopy. The estimated amount of reversibly adsorbed hydrogen was highly consistent with that obtained experimentally by hydrogen adsorption analysis, which suggested that reversible hydrogen adsorption occurred at the Ni/Si-O interface.