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Abstract: (CuIn) x Zn2(1-x)S2 (x = 0.01–0.5) microspheres were prepared by a simple hydrothermal method. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Visible diffuse reflectance spectra (UV–Vis), Raman scattering spectra and Brunauer-Emmett-Teller (BET) surface area measurement. It was found that the (CuIn) x Zn2(1-x)S2 samples formed solid solution only in the presence of surfactant cetyltrimethylammonium bromide (CTAB). CTAB enabled the increase of the surface area for the (CuIn) x Zn2(1-x)S2 solid solutions. Diffuse reflection spectra of the solid solutions shifted monotonically to long wavelength side as the value of x increased. The photocatalytic H2 evolution activity under visible-light irradiation of the solid solutions was evaluated. The result showed that the activity depended on their corresponding compositions closely. Ru (1.5 wt%)-loaded (CuIn)0.2Zn1.6S2 showed the highest photocatalytic activity of 198.09 μmol h−1 under visible-light irradiation, and the apparent quantum yield amounted to 15.45% at 420 nm. Furthermore, the density functional theory (DFT) calculations showed that the solid solution with the ration of ZnS and CuInS2, 6:1, was a direct band gap semiconductor. The valence band consisted of the hybrid orbital of S 3p and Cu 3d and the conduction band consisted of In 5s5p orbital mixed with Zn 4s4p. The energy band structure resulted in the visible-light response of the solid solution, and affected its photocatalytic performance. [Copyright &y& Elsevier]

Abstract: Cubic and rhombohedral ZnIn2S4 were synthesized by thermal sulfidation of Zn–In mixed oxide precursor in H2S atmosphere at different temperatures. Cubic ZnIn2S4 was obtained when Zn–In mixed oxide precursor was sulfurized at 400°C. With sulfidation temperature increasing from 400 to 800°C, the crystal phase of ZnIn2S4 gradually turned from cubic to rhombohedral, which was demonstrated by different analysis techniques such as XRD, Raman, SEM, etc. UV–vis absorption spectra indicated that cubic ZnIn2S4 displayed better light absorption property than rhombohedral ZnIn2S4, with band gaps calculated to be 2.0 and 2.5eV, respectively. However, under visible light irradiation, rhombohedral ZnIn2S4 photocatalyzed H2 evolution from aqueous sodium sulfite/sulfide solution efficiently, whereas cubic ZnIn2S4 was not active for this reaction. The photoluminescence property revealed the different dynamics of photogenerated carriers, which made a predominant contribution to the increasing photocatalytic performances of ZnIn2S4 with crystal phase turning from cubic to rhombohedral. [Copyright &y& Elsevier]