Despite the rapid development and enormous success of organic–inorganic hybrid halide perovskites (AB′X 3), such as CH3NH3PbI3 as absorbers for perovskite-based solar cells (PSCs), the commercial applications of photovoltaic techniques still face several challenges, such as decomposition when exposed to light and moisture, and lead toxicity. On the other hand, the double perovskites (A 2 B′B″X 6) are derived from the AB′X 3 when half of the octahedrally coordinated B′-cations are partially replaced by the suitable B″-cations. They are attracting attention due to a new design strategy to replace Pb2+ ions with the couple of a monovalent M + ion and a trivalent M 3+ ion, leading to a new family of quaternary double perovskites. In this way, we aim to synthesize and characterize Cs2AgSbCl6 powdered samples, designed for solar cell applications. The crystalline phase and morphological features are investigated by X-ray powder diffraction (XRPD), neutron powder diffraction (NPD), scanning electron microscopy (SEM) in complement with UV–vis spectroscopy, showing a suitable band gap of 2.7 eV. The solution synthesis method proved to be efficient in obtaining polycrystalline-Cs2AgSbCl6 samples in a cubic ordered phase. DFT calculations also provided insights on the vibrational properties of Cs2AgSbCl6, corroborating the experimental data and elucidating the optical activity of Raman and infrared modes.

Skutterudite‐type pnictides based on CoSb3 are promising semiconductor materials for thermoelectric applications. An exhaustive structural characterization by synchrotron X‐ray powder diffraction of different M‐filled CoSb3 (M = Y, K, Sr, La, Ce, Yb) skutterudites, with a panoply of M atoms with very different chemical nature, allows to better understand the effects of filling from a crystallo‐chemical point of view. These analyses focus on the correlation of chemical and structural features with the enhanced thermoelectric properties displayed by certain families of filled‐CoSb3 skutterudites. These are mainly determined by Sb positional parameters, yielding Oftedal plots that depend on the filling fraction, ionic state, and atomic radius of the filler. Together with the distortion of [Sb4] rings and [CoSb6] octahedra present in the skutterudite structure, these results are linked to the band‐convergence concept and its influence on the thermoelectric transport properties. Here, the structural changes observed in the different chemical compositions are relevant to understand the improved thermoelectric performance of single partially filled n‐type skutterudites.

Herein, a one-step solvothermal method was applied to produce CuBi2O4/CuO heterojunctions containing nanocolumns with small platelike nanoparticles homogeneously distributed over its surface. The photocatalytic activity of the heterojunctions was evaluated through the photodegradation of Methylene Blue (MB) dye and Metronidazole (MTZ) under simulated solar light and visible light irradiation, respectively. The heterojunction CuBi2O4/CuO-b showed an enhanced photocatalytic performance with 98% removal of MB (@2 sun simulated solar irradiation) and 36% removal of MTZ (@1 sun visible light) within 60 min of irradiation, compared to the results obtained with the pristine materials (CuO and CuBi2O4) or the other composite synthesized CuBi2O4/CuO-a. The apparent quantum efficiency for MB photocatalytic degradation using the optimized photocatalyst and 180 min of light irradiation is ∼2.1%, under the excitation wavelength of 540 nm. This enhanced photocatalytic performance is a result of an effective charge separation through a type-II heterojunction, indicating that photoinduced electrons transfer from CuBi2O4 to CuO nanoparticles and the photoholes migrate in the opposite direction. The main reactive species responsible for the photocatalytic degradation of the organic pollutant molecules were the photogenerated holes. Finally, the best photocatalysts were reused and presented good stability over three cycles, endorsing their promise as candidates for photocatalytic applications.

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