Synthesis and photoactivity of anatase porous single crystals with different pore sizes

Abstract

In this paper, anatase porous single crystals (PSCs) with different pore sizes were hydrothermally synthesized by using silica spheres as template. The products exhibit uniform porous structure which is consistent with silica template dimensions. Sharp Laue diffraction patterns, uniform lattice frings in different regions and occurrence of partial porous single crystal unequivocally prove monocrystalline nature of the samples. All PSC samples display high degree of crystallinity. Specific surface area increases with decrease of pore size and adsorption–desorption isotherms of type IV further confirm porous structure of PSCs. All samples show the strong absorption of ultraviolet light, the extent of which increases with decrease of pore size. Photoluminescence intensity decreases as pore size decreases, however, the intensity for S1 sample with minimum pore size is somewhat higher than that of S2. Photocatalytivity tests show the similar results which may be attributed to the combined effect of the surface active sites, the exchange between species in holes and those outside of PSCs, and electron mobility in framework. Moreover, the “seeding template-crystallization” mechanism for PSCs formation was discussed in detail. Based on these results, PSCs anatase with different purposes can be achieved by means of precise adjust for pore dimension and surface area.