Novel antimonate photocatalysts MSb2O6 (M = Ca, Sr and Ba): a correlation between packing factor and photocatalytic activity.

Well-crystallized MSb(2)O(6) (M = Ca, Sr and Ba) powders synthesized by solid state reactions exhibit an interesting photocatalytic activity order of Ba > Sr > Ca for organic pollutant (methylene blue and phenol) degradation and hydrogen production from water under UV light irradiation. A simple model, crystal packing factor (PF), was introduced to account for the activity difference. Nine series of photocatalysts involving 26 compounds were experimentally investigated to further substantiate the model, a lower PF being correlated to a higher photocatalytic activity. This correlation between packing factor and photocatalytic activity also holds for some 40 literature examples of 83 compounds of d(0) cations and d(10) cations. This applicable criterion for ranking photocatalytic materials of similar chemistry or structure can be rationalized through the influence of structural packing on carrier lifetimes and mobilities.