Quasi-linear dependence of cation filling on the photocatalysis of A(x)BO3-based tunnel compounds.

A series of A(x)BO(3)-based oxides, (A1)(4)(A2)(2)(A3)(4)Nb(10)O(30) (A1 = Sr, Ba; A2 = Na, K; A3 = □) as deficient perovskites, ATiO(3) (A = Mg, Ca, Sr, Ba) as ideal perovskites are prepared by solid-state reaction method, and investigated as novel tunnel photocatalysts. The efficiency exhibits a high dependence on the cation filling in the respective tunnels of these compounds. Generally, lower cation filling contributes to a higher activity. The cation filling is rationalized by the crystal packing factor (PF), the photocatalytic efficiency decreases quasi-linearly with PF. Moreover, the linear correlation also exists in the literature involving tunnel photocatalysts of Bi(2)RNbO(7) (R = Y, rare earth element), MIn(2)O(4) (M = Ca, Sr, Ba), ATaO(3) (A = Li, Na, K), etc. Such linear correlation of photocatalysis with the crystal structure has not been reported in the literature. The study of structure-modification by controlling cation-filling for improving activity sheds light on the mechanism of photocatalysis and on developing new high-performance photocatalysts.