Design and synthesis of ternary semiconductor Cu7.2(SexS1−x)4 nanocrystallites for efficient visible light photocatalysis

A new series of ternary semiconductor compounds, Cu 7.2 (Se x S 1− x ) 4 (0.2 ≤ x ≤ 0.8) nanocrystallites, that exhibited good photocatalytic activity under visible-light irradiation, were facilely synthesized under mild conditions. The Cu 7.2 (Se x S 1− x ) 4 nanocrystallites were characterized by powder X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy and UV-Visabsorption spectra. From X-ray data it is found that the cell constant a of different samples varies linearly with the composition x as: a (Å) = 5.5959 + 0.1586 x . UV-Visabsorption spectra indicate that the apparent band gap energies can be tuned by adjusting the composition x so as to better match to the whole solar spectrum. Unlike the most studied TiO 2 that only responds to the UV-light irradiation, the present Cu 7.2 (Se x S 1− x ) 4 nanocrystallites exhibited much better photocatalytic activity under visible light on degradation of RhB. It is believed that the photocatalytic superiority of the Cu 7.2 (Se x S 1− x ) 4 nanocrystallites is mainly due to the compositional gradient arisen from uneven distribution of Se/S compositions in the compounds, which may induce a more efficient charge separation/transport in the Cu 7.2 (Se x S 1− x ) 4 photocatalysts. Ternary semiconductor Cu 7.2 (Se x S 1− x ) 4 (0.2 ≤ x ≤ 0.8) nanocrystallites with better photocatalytic activity on degradation of RhB under visible light were facilely synthesized under mild conditions.