Nanoporous Au exhibit catalytic degradation of methyl orange (MO) solution while counterpart bulk Au does not. Other nanoporous metals such as Pd and Ni also exhibited the catalytic MO degradation. Because the degradation occurred under dark conditions, it is clearly distinguished from photocatalytic degradation conventionally observed in TiO2 and ZnO.

The magnetic moments of the fcc/fcc, hcp/hcp twin and fcc/hcp twin-like boundaries in cobalt were investigated by first-principles calculations based on density functional theory. The magnetic moments in fcc/fcc were larger than those of the bulk fcc, while the variations in the magnetic moment were complicated in hcp/hcp and fcc/hcp. The magnetovolume effect on the magnetic moment at the twin(-like) boundaries was investigated in terms of the local average atomic distance and the average deviation from equilibrium; however, the complicated variations in the magnetic moment could not be explained from the magnetovolume effect. Next, the narrowing (or broadening) of the partial density of states (PDOS) width of 3d orbitals, the number of occupied states for the spin-down channel and the PDOS around the Fermi level were investigated. The entire variation in the magnetic moment at the twin(-like) boundaries could be understood in terms of these factors. Charge transfer occurred in hcp/hcp. In this case, the contributions of 4s and 4p electrons to the variation in the magnetic moment were relatively large.

Anodic polarization measurements for various ruthenium (Ru) alloys revealed that hexagonal close-packed nanoporous Ru (np-Ru) can be fabricated by dealloying or selective dissolution of manganese (Mn) from RuMn alloy. The pore size and specific surface area of fabricated npRu were 3 nm and 51.5 m 2 g ¹1 , respectively. An electron diffraction pattern suggested a polycrystalline nature of the fabricated np-Ru, which is perhaps due to the change in the crystal structure during dealloying. The oxidation of carbon monoxide (CO) was efficiently catalyzed by the npRu. The activation energy was 82 kJ mol ¹1 which is comparable to that of the polycrystalline RuO 2 /Ru catalyst. The present np-Ru is a novel candidate as a recoverable Ru catalyst.

Nanostructured Co with large lattice extension and contraction was produced by electrodepositing Co on nanoporous Au. The Co deposited showed a low magnetic saturation of 76 emu/g and a high coercivity of 462 Oe. First-principles calculations showed that the magnetic moment of a Co atom is significantly decreased by lattice contraction. Therefore, the noteworthy magnetic properties of the Co deposited are attributed to the large lattice strain. Also, molecular dynamics simulation showed that the lattice extension and contraction of about 10% are generated in the overall Co crystal. This is in agreement with the experimental results of HRTEM observation. The constraint of the movement of Co atoms by the concave structure of nanoporous Au leads to a wide spread of large strain region. V

ZnO deposited on nanoporous Au showed photocatalytic decomposition toward methyl orange (MO) under visible light, unlike ZnO sputtered on flat Au without a nanoporous structure. First-principle calculations suggested that the surface lattice disorder in nanoporous Au induced a band gap narrowing and a large built-in electric field in the adjacent ZnO, resulting in the visible light photocatalytic response.