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Two chromium chalcogenide Cs[Cr(en)2GeSe4] (1) and Cs[Cr(en)2SnSe4] (2) have been synthesized by a solvothermal method. Both compounds crystallize in the monoclinic space group P21/n. The structures of the two compounds are characterized by isolated [Cr(en)2MSe4]− clusters separated by Cs+ ions. The optical properties of the two compounds were measured which indicate a similar band gap of 1.58 eV. DFT calculations demonstrated that the valance band maximum (VBM) consist of Cr 3d orbitals and Se 4p orbitals while the conductive band minimum (CBM) are composed of Cr 3d orbitals for both compounds, which explains their similar optical band gap energies. Both compounds possess paramagnetic behaviors with the effective magnetic moment of 3.97μB for Cs[Cr(en)2GeSe4] and 3.91μB for Cs[Cr(en)2SnSe4], respectively. Field-dependent magnetization measurements demonstrated their potential as magnetocaloric materials, with the magnetic entropy change of 11.6 J (kg K)−1 for Cs[Cr(en)2GeSe4], and 14.2 J (kg K)−1 for Cs[Cr(en)2SnSe4]. [ABSTRACT FROM AUTHOR]

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 H2 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. [ABSTRACT FROM AUTHOR]