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Abstract
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CuO and Er-doped CuO nanostructures were synthesized by thermal decomposition of Cu-salophen complexes containing chloro, bromo and nitro substituents as precursors (CuL1, CuL2 and CuL3, respectively). The structure of products was characterized by FT-IR spectroscopy and XRD patterns. XRD patterns indicated that the formation of single-phase monoclinic structures without impurity and also confirmed that erbium ions are successfully doped into CuO crystal lattice. The photocatalytic activity of all samples was measured against the Reactive Black 5 dye under UV radiation. The photocatalytic mineralization of RB-5 was monitored by total organic concentration (TOC) decrease and changes in the UV–Vis spectra. The results revealed that the photocatalytic efficiency of Er-doped CuO samples is much higher than their un-doped counterparts. The highest percentage of dye decomposition was achieved using Er-doped CuO (1). The optical band gaps calculated from UV–Vis spectra were found to be 3.60 eV for both CuO (1) and Er-doped CuO (1). The PL spectrum of Er-doped CuO (1) showed a significant decrease in emission intensity, which was related to the electron-hole separation due to electron transfer from CuO conductive band to Er3+ ions. The BET analysis revealed after Er3+ doping, the surface porosity and specific surface area increased because of the appearance of some surface defects in CuO structure. FE-SEM images of both pure and doped CuO samples displayed that the powders consist of highly agglomerated nano-flakes resulting from overlapping of small particles. Further analysis of Er-doped CuO (1) with TEM indicated the prepared sample is composed of nanoparticles.
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