Synthesis of PbS quantum dots/ZnO nanorods/Ag nanowires composite photocatalysts with enhanced photocatalytic activity

Abstract

In this work, PbS quantum dots/ZnO nanorods/silver nanowires (PbS QDs/ZnO NRs/Ag NWs) composite photocatalysts were successfully synthesized. The amount of PbS QDs was controlled by the number of successive ionic layer adsorption and reaction (SILAR) cycles. The cycle was repeated 5, 9 and 13 times, respectively. Degradation of methylene blue under simulated sunlight conditions to evaluate the photocatalytic activity of materials. As expected, the PbS QDs/ZnO NRs/Ag NWs composite performs enhanced photocatalytic activity compared to ZnO NRs and ZnO NRs/Ag NWs. In addition, the experimental results show SILAR cycles have a significant effect on the loading of PbS QDs on ZnO NRs and photocatalytic activity of the composite, among different composites, the composite with 9 SILAR cycles shows the best photocatalytic performance in the degradation of methylene blue (MB). MB can be almost completely degraded in 30 min. The radical-trapping experiments and electron spin resonance demonstrate that superoxide anion radicals and photogenerated holes are main reactive species for photocatalytic degradation.