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

Abstract

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 K_2xCa_1−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 H₂ evolution. The optimized composition of K_2xCa_1−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.