Fabrication of erbium-doped spherical-like ZnO hierarchical nanostructures with enhanced visible light-driven photocatalytic activity

Erbium-doped spherical-like ZnO hierarchical nanostructures (Er/ZnO) were newly synthesized via a facile and surfactant-free chemical solution route. Field emission scanning electron microscopy and transmission electron microscopy observations showed that the assemblies were composed of large amounts of interleaving nanosheets with the thickness of about 15 nm. X-ray diffraction and energy dispersive X-ray results revealed that Er ion was successfully doped into ZnO. The Er doping increased the visible light absorption and a red shift appeared in UV–vis diffuse reflection spectra for Er/ZnO. Photoluminescence spectra showed that the improvement of visible emission in the Er/ZnO was a result of oxygen vacancy of defect increased by addition of Er in ZnO. The photocatalytic tests revealed that Er/ZnO was a new promising photocatalyst in remediation of water contaminated by organic pollutants under visible light irradiation.

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► Erbium-doped spherical-like ZnO hierarchical nanostructures were fabricated.
► Spherical-like ZnO nanostructures were made by self-assembly of nanosheets.
► A possible growth mechanism of spherical-like ZnO nanostructures was discussed.
► Er doping enhanced the photocatalytic efficiency of ZnO under visible light.