Insights into photoluminescence property and photocatalytic activity of cubic and rhombohedral ZnIn2S4

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 degrees C. With sulfidation temperature increasing from 400 to 800 degrees 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 2.5 eV, respectively. However, under visible light irradiation, rhombohedral ZnIn2S4 photocatalyzed H-2 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. (C) 2011 Elsevier Inc. All rights reserved.