Ion-exchange synthesis and enhanced visible-light photocatalytic activities of CuSe-ZnSe flower-like nanocomposites

CuSe-ZnSe flower-like nanocomposites with uniform diameters can be easily fabricated on a large scale by a controlled ion-exchange reaction between monodisperse ZnSe flower-like nanostructures and Cu2+ ions in solution. The difference of solubility products (Ksp) of ZnSe and CuSe is the main driving force for the formation of these flower-like nanocomposites. The Cu content greatly influences the physical properties and photocatalytic activity of obtained CuSe-ZnSe nanocomposites. The as-produced CuSe-ZnSe nanocomposites show tremendous enhancements on the photocatalytic degradation ratio of organic dyes methylene orange (MO) and methylene blue (MB) under visible-light irradiation. The 8 wt.% CuSe-ZnSe sample exhibits the highest degradation ratio for both MO (ca. 100%, 90 min) and MB (ca. 96%, 60 min), which are over 4 times and 2.5 times than that of the pure ZnSe sample, respectively. Based on the data of UV–vis diffuse reflection spectra, XPS and PL spectra, the enhancements of photocatalytic activities of CuSe-ZnSe flower-like nanocomposites are due to the effective separation of photo-electrons and holes induces by the direct initiates interfacial charge transfer (IFCT) from the valence band (VB) of ZnSe to CuSe, which results in the reduction of CuSe to Cu2Se. This work not only highlights the potential use of visible-light-driven CuSe-ZnSe flower-like nanocomposites photocatalysts, but also emphasizes the simple ion-exchange in situ growth method for the preparation of selenides heterogeneous structures.

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► The CuSe-ZnSe flower-like nanocomposite can be easily synthesized by using ion-exchange method.
► The content of CuSe in the nanocomposite influences the visible light photocatalytic activity.
► IFCT effect can explain the cause of enhanced visible-light photocatalytic activities of the nanocomposite.