Mixed-dimensional, three-level hierarchical nanostructures of silver and zinc oxide for fast photocatalytic degradation of multiple dyes

Three-level AgNWs/ZnO NRs/AgNPs hierarchical structures resembling nanoscale pine trees have been successfully synthesized using a three-step solution method. In particular, AgNPs were incorporated primarily for plasmonic light harvesting. The PL intensity of the hierarchical nanostructures was disclosed to drop by 89% at the most from the value of pure ZnO NRs, which indicated the remarkable retardation of carrier recombination. It is worth noting that the photocatalytic performance of the hierarchical nanostructures dominated over their counterparts such as pure ZnO NRs and AgNWs/ZnO NRs hybrid structures. Moreover, their photocatalytic efficiency remained high for a variety of organic dyes like methylene blue, methyl orange, and rhodamine B. The hierarchical nanostructures turned out to degrade 96.5% of dyes on average within a 30 min of solar light irradiation. In addition, they were also found to possess good recyclability. The overwhelming photocatalytic performance of the AgNWs/ZnO NRs/AgNPs hierarchical structures was discussed on the basis of fast electron transfer and surface plasmon resonance. The unique design-and-superb performance of the hierarchical nanostructures can offer a new possibility to step closer to the realization of ideal photocatalysts with high reactivity for a wide range of pollutants. (C) 2019 Elsevier Inc. All rights reserved.