One-Pot Synthesis of Ag/ZnO Self-Assembled 3D Hollow Microspheres with Enhanced Photocatalytic Performance

In this paper, three-dimensional (3D) Ag/ZnO hollow microspheres with different Ag contents were prepared through a facile one-pot hydrothermal method assisted by sodium alginate. The samples were structurally characterized by X-ray diffraction, field emission scanning electron microscope, high resolution transmission electron microscope, and X-ray photoelectron spectroscopy. It was shown that all samples were composed of metallic Ag and wurtzite ZnO; the 3D Ag/ZnO hollow microspheres were constructed from self-assembled 1 D Ag/ZnO nanorods; the surface O species can be categorized to surface hydroxyl oxygen (O-H) and crystal lattice oxygen (O-L), and the ratio between them varies with different Ag loadings. The photocatalytic performance for the degradation of Orange G was also evaluated. The results show that such hierarchical Ag/ZnO hollow microspheres exhibit significantly enhanced photocatalytic efficiency. Investigation of the relationship of photoluminescence (PL) spectra and surface structure of the samples with their photocatalytic performance indicated that optimized amount of Ag deposits not only acted as electron sinks to enhance the separation of photoindUced electrons from holes, but also elevated the amount of the surface hydroxyl, leading to the formation of more hydroxyl radicals (center dot OH) and then the higher photodegradation efficiency.