[en] Sm³⁺-doped SrSnO₃ (SrSnO₃:Sm³⁺) nanopowders were synthesized by a simple hydrothermal method and followed by a heat treatment process. The as-synthesized nanopowders were assembled in dye-sensitized solar cells (DSSCs) to investigate their photoelectric properties. X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive spectrometer (EDS) confirmed the formation of SrSnO₃:Sm³⁺ nanopowders with perovskite structure. The ultraviolet-visible absorption spectra and photoluminescence spectra indicate a down-conversion from ultraviolet light to visible light which matches the strong absorption region of the N719 dye. The DSSC based on SrSnO₃:Sm³⁺ photo-anode improved its photoelectric conversion efficiency (η) via the down-conversion of doped Sm³⁺. Under the irradiation of the simulated sunlight with 100 mW/cm², the DSSC based on SrSnO₃ doping with Sm³⁺ of 0.6 wt% showed the highest η of 1.54%, which improved 71.11% compared with the DSSC based on pure SrSnO₃. .

[en] Graphical abstract: The schematic diagram of visible light driven photocatalytic reaction happened on the surface of Co-doped ZTO nanoparticles. - Highlights: • Co-doped Zn₂SnO₄ nanoparticles were synthesized by a hydrothermal method. • The effect of Co doping content on photocatalytic activity of Zn₂SnO₄ were investigated. • The maximum degradation rate of RhB was 93% when Co doping content was 2 mol%. • A possible mechanism of photocatalytic degradation of RhB was proposed. - Abstract: Various molar concentrations of Co-doped Zn₂SnO₄ nanoparticles were synthesized by hydrothermal method. The as-prepared samples were characterized by XRD, XPS, FESEM, TEM, UV–Vis and PL. The result of XPS revealed that the Co dopant displayed a chemical state of Co²⁺ in Zn₂SnO₄ lattice. UV–Vis results revealed that the absorption edge of samples shifted towards visible light region gradually with the increase of Co doping content. The PL intensity weakened significantly for the Co-doped Zn₂SnO₄, which indicates that the recombination of photo-generated electrons and holes was suppressed strongly. The photocatalytic activity of Zn₂SnO₄ was observed by photodegradation of RhB under visible light irradiation. The influences of Co doping content on photocatalytic activity of Zn₂SnO₄ were investigated. The experiment results indicated that the maximum degradation rate of RhB was 93% in 120 min when Co²⁺ molar concentration was 2 mol%. Furthermore, a possible mechanism of photocatalytic degradation of RhB was discussed.