Study on the Photocatalytic Degradation of MB by the ZnO@PDA and ZnO-Ag@PDA

Photocatalysis properties enhanced by metal and organic polymer has been received more interest because of their ability to directly or indirectly degrade pollutants. The effect of PDA (polydopamine) and Ag nanoparticles on the different phases of ZnO to degrade organic dyes under visible and UV-vis light was investigated. ZnO@PDA, ZnO-Ag, and ZnO-Ag@PDA nanoparticles were synthesized. It’s shown that Ag particles with sizes of less than 20 nm were deposited evenly on the ZnO. There were a few changes in the structure of ZnO@PDA or ZnO-Ag @PDA. When the ZnO was coated by PDA, the photocatalytic activity could be enhanced. The photocatalytic activity under UV-vis and visible light of the ZnO@PDA were effectively improved. The degradation rate of ZnO-Ag@PDA was 97.9% under UV-vis light for 20 mins, which was 16.1% higher than that of ZnO. The photocatalytic activity of ZnO-Ag@PDA reached the maximum after polymerizing for 2 hours. The photocatalytic efficiency of ZnO-Ag@PDA-2h under UV-vis for 30 minutes can reach higher than 99.01%. The photocatalytic performance decreased rapidly with the increasing cycles. When the number of cycles was 5, the degradation rate was 65.84%. Afterward, the degradation rate changed small and became stable.