Tailoring the photocatalytic activity of layered perovskites by opening the interlayer vacancy via ion-exchange reactions

Layer-structured materials have shown great promise in photocatalytic applications. The criteria for effective design and selection of superior layered photocatalysts according to their crystal structures are extremely important. Herein, a series of layered perovskites MLa2Ti3O10 (M = Ca, Sr, Ba) and K2xCa1-xLa2Ti3O10 (x = 0.05, 0.11, 0.25) were prepared by an ion-exchange approach from K2La2Ti3O10. Their photocatalytic properties were evaluated by the degradation of methyl orange (MO) and phenol and by photocatalytic hydrogen evolution. Their catalytic activities were significantly improved compared to K2La2Ti3O10, in the order Ca > Sr > Ba > K for both organic pollutant degradation and H-2 evolution. The optimized composition of K2xCa1-xLa2Ti3O10 with x = 0.11 shows an increase of four times in photocatalytic efficiency in comparison to pristine K2La2Ti3O10. The underlying mechanism of the improved performance is discussed in detail in terms of the packing factor model, which demonstrates that a more open structure with a lower packing factor possesses higher photocatalytic activity in the layered perovskites.