Nanostructured carbon—Ni(OH)₂ composites

Abstract

Deposition of Ni(OH)₂ from an aqueous solution of Ni(N₃)₂ onto highly porous carbon matrices of two types with different porous structure afforded high-purity nanostructured hydroxide—carbon composites with a regular spatial morphology, which are filled with Ni(OH)₂ nanocrystallites (up to 30.9 wt.%) and have high values of specific suface area (up to 1875 m² g^–1) and porosity (up to 2.65 cm³ g^–1). Largeand small-angle X-ray diffraction and low-temperature nitrogen absorption on composites showed that nanocrystallites with a brucite-type layered structure form as plates with a thickness of 2—4 nm and a size along the developed face (001) of 25—30 nm in mesopores and on the outer surface of matrices. The degree of mesopore filling with crystallites depends on the mesopore size and the composition of composites; the micropores remain mainly unfilled. The increase in the hydroxide content results in pore size redistribution: in general, the distribution curves shift in favor of smaller mesopore sizes; the portion of pores with sizes comparable with the thickness of filler nanoplates (3—6 nm), as well as the portion of mid-sized pores (20—30 nm) decrease significantly in favor of smaller pores (8—12 nm). Partial blocking (clogging) of pores with filler nanocrystallites was also observed.