Hydrothermal fabrication and enhanced photocatalytic activity of hexagram shaped InOOH nanostructures with exposed {0 2 0} facets

Hexagram shaped InOOH nanostructures with exposed {0 2 0} facets were synthesized in large quantities via the hydrothermal reaction of InCl3 with NaAc, ethylene glycol and H2O system at 180–220 °C for 12 h. The six constituent nanocones of the hexagram shaped nanostructure grew along the directions perpendicular to (2 0 0 )/(2¯ 0 0), (1 0 1)/(1¯ 0 1¯) and (1¯ 0 1)/(1 0 1¯) facets of the orthorhombic InOOH through the oriented attachment process, and the top and bottom surfaces of the hexagrams were dominantly enclosed by the {0 2 0} facets. The {0 2 0} facets were stabilized by ethylene glycol, which was employed to control the growth of InOOH crystals. When the hydrothermal reaction temperature increased, the size of hexagram shaped InOOH nanostructures decreased, their specific surface area and the texture coefficient (TC) of (0 2 0) plane increased, and thus their photocatalytic activity was enhanced. The hexagram shaped InOOH nanostructures obtained at 220 °C showed higher intrinsic photocatalytic activity than Degussa P25 TiO2 for degradation of rhodamine B. The superior intrinsic photocatalytic activity was attributed to the high percentage of exposed {0 2 0} facets of the hexagram shaped nanostructures.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Hexagram shaped InOOH nanostructures were first obtained via a hydrothermal route. ► The InOOH hexagram shaped structures were formed via the oriented attachment process. ► Hexagram shaped InOOH nanostructures show higher photocatalysis than Degussa P25. ► The high intrinsic photocatalytic activity results from the exposed {0 2 0} facets.