Fabrication of urchin-like Ag/ZnO hierarchical nano/microstructures based on galvanic replacement mechanism and their enhanced photocatalytic properties

Urchin-like Ag/ZnO hierarchical nano/microstructures have been synthesized through a facile low-temperature hydrothermal growth method based on galvanic replacement mechanism. The experimental results show that the urchin-like Ag/ZnO heterostructures are formed through the epitaxial growth of ZnO nanorods on the {111} facets of Ag nanoparticles along their own c-axis. The photocatalytic properties of the products were evaluated by the degradation of RhB dye solution under ultraviolet irradiation, and the results show that the products exhibit significantly enhanced photocatalytic properties comparing with pure ZnO nanorods. The products with a Ag content of 35.64 atom % prepared with a Ag+ concentration in solution of 5mM exhibit surprisingly high degradation rate (99.5%) for RhB dye solution (4mg/L) after photocatalytic reaction for only 14min under ultraviolet irradiation. The Schottky barrier formed at the metal-semiconductor interfaces improves the segregation of charges and prevents the charge recombination, and thus significantly enhances the photocatalytic activities of the products. On the other hand, the high stability of the urchin-like Ag/ZnO hierarchical nano/microstructures can effectively prevent the aggregation of nanostructures with simultaneously preserving high photocatalytic properties due to the existence of nanosized unites. Copyright (c) 2016 John Wiley & Sons, Ltd.